New grading system for SCC.pdf

1
Boxberg M, et al. J Clin Pathol 2018;0:1–10. doi:10.1136/jclinpath-2018-205454
Novel prognostic histopathological grading system in
oral squamous cell carcinoma based on tumour
budding and cell nest size shows high interobserver
and intraobserver concordance
Melanie Boxberg,1
Christine Bollwein,1
Korinna Jöhrens,2
Peer-Hendrik Kuhn,1
Bernhard Haller,3
Katja Steiger,1
Klaus-Dietrich Wolff,4
Andreas Kolk,4
Moritz Jesinghaus,1,5
Wilko Weichert1,5
Original article
To cite: Boxberg M,
Bollwein C, Jöhrens K, et al.
J Clin Pathol Epub ahead of
print: [please include Day
Month Year]. doi:10.1136/
jclinpath-2018-205454
►
► Additional material is
published online only.To view
please visit the journal online
(http://dx.doi.org/10.1136/
jclinpath-2018-205454).
1
Institute of Pathology,Technical
University of Munich (TUM),
Munich, Germany
2
Institute of Pathology,
University Carl Gustav Carus,
Dresden, Germany
3
Institute of Medical Informatics,
Statistics and Epidemiology,
Technical University of Munich
(TUM), Munich, Germany
4
Department of Oral- and
Maxillofacial Surgery, Klinikum
Rechts der Isar, Munich,
Germany
5
German Cancer Consortium
(DKTK), Munich, Germany
Correspondence to
Dr Melanie Boxberg, Institute of
Pathology,Technical University
of Munich, Munich 81675,
Germany; Melanie.Boxberg@
tum.de
Received 15 August 2018
Revised 31 October 2018
Accepted 10 November 2018
© Author(s) (or their
employer(s)) 2018. No
commercial re-use. See rights
and permissions. Published
by BMJ.
Abstract
Aims Squamous cell carcinoma of the oral cavity
(OSCC) is a common tumour entity with a variable,
partially highly aggressive clinical course. Recently,
we proposed a novel (three-tiered) clinically useful
grading scheme strongly associated with patient
outcome in OSCC, consisting of a sum score of the
histomorphological patterns tumour budding and
cell nest size which outperforms WHO based grading
algorithms currently in use.The aim of our study was to
probe for interobserver and intraobserver reliability of
this novel grading system.
Methods 108 OSCC were retrospectively scored
according to the proposed grading scheme by three
independent pathologists—two experienced head and
neck pathologists and one pathologist in training—
blinded to each other’s scoring results.
Results The Cohen’s Kappa (κ) values for concordance
rates between experienced pathologists were κ=0.97
for the overall grade, κ=0.97 for budding activity
and κ=0.91 for cell nest size, indicating a strong
interobserver reliability of our proposed grading system.
Initial interobserver agreement was markedly lower
with the pathologist in training (κ=0.55 for overall
grade) but improved significantly after a training session
(κ=0.87 for overall grade). Intraobserver concordance
was high (κ=0.95 for overall grade), indicating a high
reproducibility of the algorithm.
Conclusions In conclusion, our study indicates that
OSCC grading based on our proposed novel scheme
yields an excellent inter-reader and intrareader
agreement, further supporting the suitability of this
grading system for routine pathological practice.
Introduction
Squamous cell carcinoma (SCC) of the head and
neck accounts for almost 90% of malignant head
and neck neoplasms with SCC of the oral cavity
(OSCC) being the most common malignancy in
this region.1 2
In clinical routine, histopathological
grading of OSCC is done according to the guide-
lines of the WHO classification of head and neck
tumours,3 4
which is based on a grading system
initially proposed by Broders et al in 1920.5
Up
to date, the most important prognostic feature for
patient outcome in OSCC is staging according to
the current TNM and UICC classification, whereas
the WHO grading does not play a major clinical
role due to its limited prognostic and predictive
impact.4 6 7
In an era of increasingly personalised therapies,
treatment planning is strongly dependent on reliable
predictive and prognostic factors. As the current
WHO grading system seems not to have this crucial
potential, several competing prognostic grading
systems for optimal patient stratification have
been proposed during the last decades, including a
multiparameter grading system,8 9
risk assessment
approaches (HR)10
and specific investigations of the
invasive margin (MG).11
Results regarding survival
prediction have been partly contradicting between
the different grading systems,12
which might in part
be due to the potentially poor reproducibility in the
evaluation of some of the included characteristics
(such as keratinisation). Furthermore, a large disad-
vantage of the systems listed above is the mixing of
classical independent staging variables (ie, depth of
invasion) with histomorphological features purely
describing tumour architecture/morphology (thus
classical components of histopathological grade)
and additional tumour-inherent but tumour cell
morphology-independent factors such as inflamma-
tory infiltrate, known to have a prognostic impact
as well. Hence, from an UICC/TNM perspective,6
none of these grading schemes fits into the current
general tumour grade definition of the TNM
manual,13 14
which explicitly excludes staging vari-
ables like depth of invasion, perineural invasion or
lymphangioinvasion from grading.
To overcome these shortcomings, we have
recently proposed and validated a novel three-
tiered histopathological grading system for OSCC
with strong independent impact on patient prog-
nosis, which comprises a numeric score based on
the solely tumour intrinsic architectural patterns
cell nest size and budding activity (table 1).15
This novel grading scheme is strongly linked to
and cross validated by comparable grading algo-
rithms recently developed for SCC of the larynx
(unpublished data), lung, oesophagus and uterine
cervix.16–19
Major prognostic impact of the feature
tumour budding has furthermore been reported for
other cancers such as breast, gastric and colorectal
adenocarcinoma.20–24
on
17
December
2018
by
guest.
Protected
by
copyright.
http://jcp.bmj.com/
J
Clin
Pathol:
first
published
as
10.1136/jclinpath-2018-205454
on
8
December
2018.
Downloaded
from

2 Boxberg M, et al. J Clin Pathol 2018;0:1–10. doi:10.1136/jclinpath-2018-205454
Original article
Table 1 Grading algorithm for oral squamous cell carcinomas as
proposed by Boxberg et al15
SCC grading algorithm
Implemented criteria Point(s)

Tumour budding activity/10 HPF
No budding 1

15 budding foci 2

≥15 budding foci 3

Smallest cell nest size
15 cells 1
5–15 cells 2
2–4 cells 3

Single cell invasion 4
Tumour grading Total score

Well differentiated (G1) 2–3

Moderately differentiated (G2) 4–6

Poorly differentiated (G3) 7
HPF, high power field; SCC, squamous cell carcinoma.
But the validity and usefulness of a given grading system for
diagnostic practice depends on its prognostic impact and on
its reproducibility, including interobserver and intraobserver
agreement.25 26
Interobserver disagreement may have thera-
peutic consequences for patients as summarised by Fleming:27
‘…if a [histopathologic pattern] cannot be reliably and repro-
ducibly identified … by a broad group of pathologists, the fact
that it is clinically important is almost meaningless and, at worst,
misleading…’.
Measurement of interobserver agreement for categorical
outcomes in general is performed by calculating Cohen’s Kappa
(κ). According to Altman,28
values of κ0.20 represent poor
agreement, 0.21–0.40 fair, 0.41–0.60 moderate, 0.61–0.80 good
and values ≥0.81 and higher very good agreement. Reported
interobserver reliability for the various grading systems including
the WHO grading system varies from 0.25 for the pattern of
invasion grading up to 0.84 for the HR model.11 29–32 33–37
Thus, the aim of the present study was to assess the interob-
server and intraobserver reliability of our proposed grading
system in prototypical OSCC cases. To this end, 108 OSCC were
evaluated according to our scoring system by two experienced
head and neck pathologists and one resident in pathology before
and after training and interobserver reliability was calculated by
Cohen’s Kappa. Furthermore, one of the experienced patholo-
gists repeated scoring to determine intraobserver reliability.
Material and methods
Tissue
Total 108 cases of a previously characterised cohort of n=157
OSCC15
were evaluated. To focus our evaluation on prototypical
oral squamous cell carcinomas, cases which exceeded the oral
cavity as well as those with p16 expression on immunohisto-
chemistry15
were excluded from our study as were cases in which
tumour area covered below 20% of the HE stained slide. All
carcinomas were surgically resected in the department of Oral
and Maxillofacial Surgery of the Klinikum Rechts der Isar,
University Hospital of the Technical University Munich between
2007 and 2012 according to a standard protocol derived from
the German guidelines for treatment of OSCC.38
For each case,
the slide with the highest tumour burden out of all slides gener-
ated for routine diagnostics was chosen for evaluation by the
reviewers.
Reviewers
Three reviewers, blinded to each other’s scoring results as well
as clinical information, participated in the study. KJ (reviewer 1)
from the Charité University Hospital in Berlin and MB (reviewer
2) from the Institute of Pathology of the TU Munich are board
certified pathologists with expert knowledge in head and neck
pathology. CB (reviewer 3) from the Institute of Pathology of the
TU Munich is a pathologist in training in her second year with
general knowledge in surgical pathology but without special
training in head and neck pathology.
Six months after the first scoring round, CB was trained by MB
on a subgroup of 50 independent cases. Following the training,
she undertook a second scoring round. To analyse intraobserver
variability, the slide set was evaluated a second time by MB. Time
between scorings was 6 months for both reviews. Cases were
scrambled every time between the different evaluation rounds.
Histopathological evaluation
Histopathological evaluation of tumour budding activity in 10
high power fields (HPF) and cell nest size was carried out as previ-
ously described15
(Field diameter 0.55 mm). Tumour budding
was defined as branching of small tumour nests harbouring 5
tumour cells into the surrounding parenchyma/stroma with low
budding activity defined as 1–14 and high budding activity ≥15
budding nests per 10 HPF. Clustered tumour cells surrounded
by tumour stroma were defined as cell nests. OSCC nest size
was classified according to the size of the smallest invasive cell
nest. This means that in principle already one small nest in a
general background of large nests leads to a higher nest size
score. Tumour cell clusters composed of 15 tumour cells were
classified as large nests, 5–15 tumour cells as intermediate nests,
small nests consisted of 2–4 tumour cells. Single cell invasion was
defined as isolated discohesive tumour cells showing no nested
architecture. The final grading score was calculated by adding
up the score for budding activity in 10 HPF and cell nest size as
previously described. OSCC with a grading score 2 or 3 were
classified as well differentiated (G1), OSCC with a grading score
between 4 and 6 were considered to be intermediately differen-
tiated OSCC (G2) and poor differentiation (G3) was assigned to
OSCC with a grading score of 7 (table 1).
Statistics
All calculations were done using SPSS V
.24 (IBM, Armonk, New
York, USA). Absolute and relative frequencies are presented for
categorical variables. Cohen’s kappa was used to assess interob-
server and intraobserver reliability. All statistical significance
tests were performed considering a two-sided 5% significance
level.
Results
Histopathological evaluation
Table 2 summarises the results of the histopathological evalua-
tion of all reviewers. The subsequent section includes the values
obtained by reviewer 1: tumour budding activity was observed
in 75/108 (69.4%) cases. Among these, low budding activity
was observed in 50/108 (46.3%) and high budding activity in
25/108 (23.1%) cases. Cell nest size was distributed as follows:
large cell nests 16/108 (14.8%), intermediate cell nests 17/108
(15.7%), small cell nests 29/108 (26.9%), single cell invasion
46/108 (42.6%).
Calculation of the previously described grading score resulted
in score 2 in 16/108 (14.8%), score 3 in 17/108 (15.7%), score
5 in 28/108 (24.9%), score 6 in 23/108 (21.3%) and score 7
on
17
December
2018
by
guest.
Protected
by
copyright.
http://jcp.bmj.com/
J
Clin
Pathol:
first
published
as
10.1136/jclinpath-2018-205454
on
8
December
2018.
Downloaded
from

3
Original article
Table 2 Results of histopathological evaluation of oral squamous cell carcinomas of reviewers R1, R2 (first and second evaluation) and R3 (before
and after training)
Reviewer
R1;
KJ
R2;
MB
R2;
MB (second round)
R3;
BC
R3;
BC (after training)
n % n % n % n % n %
Cell nest size Large 16 14.8 15 13.9 15 13.9 9 8.3 14 13.0
Intermediate 17 15.7 17 15.7 15 13.9 15 13.8 15 13.9
Small 29 26.9 29 26.9 28 25.9 41 38.0 32 29.6
Single cells 46 42.6 47 43.5 50 46.3 43 39.8 47 43.5
Budding activity Absent 33 30.6 32 29.6 30 27.8 24 22.2 29 26.9
Low 50 46.3 50 46.3 51 47.2 47 39.8 46 42.5
High 25 23.1 26 24.1 27 25.0 37 34.3 33 30.6
Grading score 2 16 14.8 15 13.9 16 14.8 9 8.3 14 13.0
3 17 15.7 17 15.7 14 13.0 15 13.9 15 13.8
5 28 24.9 27 25.0 27 25.0 39 36.1 29 26.9
6 23 21.3 24 22.2 25 23.1 10 9.3 19 17.6
7 24 22.2 25 23.1 26 24.1 35 32.4 31 28.7
Grading G1 33 30.6 32 29.6 30 27.8 24 22.2 29 26.9
G2 51 47.2 51 47.2 52 48.1 49 45.5 47 43.5
G3 24 22.2 25 23.1 26 24.1 35 32.4 32 29.6
Figure 1 Representative HE stained oral squamous cell carcinomas
(OSCC). (A), (C) showing OSCC with tumour budding activity as
indicated by presence of cell nests containing 5 tumour cells (small
cell nestsand single cell infiltration *). (B), (D) showing OSCC with
intermediate and large cell nest sizes without evidence of tumour
budding activity.
in 24/108 (22.2%) cases. According to the grading scheme, G1
(well differentiation; score 2 and 3) was assigned to 33/108
(30.6%), G2 (intermediate differentiation; score 4–6) to 51/108
(47.2%) and G3 (poor differentiation; score 7) to 24/108
(22.2%; figure 1) of OSCC.
Interobserver variability—correlation of morphological
patterns
Scores obtained for cell nest size and budding activity by
reviewers 1 and 2 were concordant in 101/108 (93.5%) and
106/108 (98.1%) cases, respectively. Calculation of Cohen’s
Kappa for the pattern cell nest size revealed κ=0.91 (p0.001).
The corresponding value for the pattern budding activity was
κ=0.97 (p0.001). As expected, the level of consensus between
reviewers 1/2 (head and neck pathologists) and reviewer 3
(resident in training) was considerably lower. Concerning cell
nest size, concordance of scores between reviewer 1/2 and 3
was found in 74/108 (68.5%) and 73/108 (67.6%), respectively.
The resulting Kappa value was κ=0.55 and κ=0.53. Concor-
dance rates concerning budding activity were similarly with
κ=0.55 for reviewers 1 and 3 and κ=0.54 for reviewers 2 and
3 (p0.001; figures 2 and 3). Table 3 shows cross tables of
interobserver concordance for both patterns between reviewer
1 versus 2 and 1 versus 3, and online supplementary table 1
includes cross tables of interobserver concordance between
reviewers 2 and 3.
Interobserver variability—correlation of grading
Reviewers 1 and 2 reached identical histopathological grades
(G1-G3) in 106/108 cases (98.1%). Consequently, Cohen’s
Kappa was 0.97, indicating an extremely high interobserver
agreement. With 77/108 (71.3%) cases rated similar, discor-
dance was higher between reviewers 1 and 3 as well as 2 and 3
resulting in κ=0.55 for both calculations (table 3, online supple-
mentary table 1, figure 4). Online supplementary table 2 gives
additional information for underlying grading scores.
Interobserver variability after training
After training of rater 3, the concordance between the experi-
enced rater 1/2 and rater 3 increased considerably concerning
both, the patterns cell nest size (concordant cases reviewer 1 vs 3:
83/108 (76.9%); reviewer 2 vs 3 86/108 (79.6%)) and budding
activity (concordant cases reviewer 1 vs 3: 97/108 (89.8%);
reviewer 2 vs 3 99/108 (91.7%)) as well as with respect to the
final grading (concordant cases reviewer 1 vs 3: 97/108 (89.8%);
reviewer 2 vs 3 99/108 (91.7%)). Cohen’s Kappa for rater 1
and rater 3 was calculated as κ=0.67 for cell nest size, κ=0.87
for budding activity and κ=0.84 for grading (p0.001). The
respective values for rater 2 vs rater 3 were as follows: cell nest
size κ=0.71; budding activity κ=0.87; grading 0.87 (p0.001;
figures 2–4). Corresponding cross tables are shown in table 3
and online supplementary table 1.
on
17
December
2018
by
guest.
Protected
by
copyright.
http://jcp.bmj.com/
J
Clin
Pathol:
first
published
as
10.1136/jclinpath-2018-205454
on
8
December
2018.
Downloaded
from

Original article
Figure 2 Kappa values for evaluation of the patterns budding activity and cell nest size as well as final grading comparing scoring of reviewers 1, 2
and 3.Although reviewers 1 and 2 were not trained, kappa values for their comparison are given in both graphs for better comparability. Upper row:
kappa values before training of reviewer 3; lower row: kappa values after training for reviewer 3. Kappa κ≥0.81 (dashed line) indicating very good
interobserver agreement according to Altman.28
Intraobserver variability
To assess intraobserver variability, reviewer 2 scored the slide set
twice after a time gap of more than 6 months. Concordance for
the patterns cell nest size and budding activity was high, resulting
in a Cohen’s Kappa of κ=0.74 (89/108; 82.4% concordant
cases) for nest size and κ=0.97 (105/108; 97.2% concordant
cases) for budding activity, respectively. The resulting grading
was concordant in 105/108 (97.2%) OSCC with a kappa value
κ=0.95 (p0.001; table 4).
Discussion
The histopathological diagnosis of a tumour includes the eval-
uation of its differentiation, which is reflected by the tumour
grade. It represents the basis for clinical patient stratification
to achieve optimal therapy decision-making. The purpose of a
grading system is therefore to give exact prognostic and predic-
tive information about the patient’s disease course and potential
response to treatment schemes.25 39
Consequently, the clinical
value of a histopathological grading system depends on (1) the
correlation between the aggressiveness of the individual tumour
and the corresponding histopathological tumour differentiation
evaluation scheme and (2) on the reproducibility of the applied
grading system in terms of interobserver and intraobserver
agreement of pathologists.25 26
Our recently proposed histopathological grading scheme
for OSCC15
consists of the morphological patterns ‘cell nest
size’—scored from 1 (large cell nests15 cells) to up to 4 (single
cell invasion)—and ‘tumour budding activity’—scored from 1
(no budding activity) to up to 3 (15 budding nests/10HPF).
Both criteria, cell nest size and budding activity, have previously
been described as surrogate parameters for tumour aggressive-
ness in head and neck SCC40–44
and in a variety of other solid
cancers.15 18 19 21 22
Both morphological patterns are related
to loss of cancer cell adhesion and might thus also represent
on
17
December
2018
by
guest.
Protected
by
copyright.
http://jcp.bmj.com/
J
Clin
Pathol:
first
published
as
10.1136/jclinpath-2018-205454
on
8
December
2018.
Downloaded
from

5
Original article
Figure 3 Number of cases with agreement/disagreement concerning scoring of the pattern cell nest size (score 1–4) comparing ratings of reviewers
1, 2 and 3 before and after training. (A) Y-axis: reviewer 1; x-axis: reviewer 2; (B) y-axis: reviewer 1; x-axis: reviewer 3 before training; (C) y-axis:
reviewer 1; x-axis: reviewer 3 after training.
morphologic features of epithelial-mesenchymal transition, a
biological phenomenon which enables tumour cells to acquire a
more motile, infiltrative phenotype.45–48
The above-mentioned studies, including ours, suggest that
these two histopathological features reflect a given OSCC’s
biological potential better than ‘established’ grading factors such
as nuclear pleomorphism, degree of keratinization, mitotic count
and host response, which are parts of various other proposed
OSCC grading systems including the grading scheme currently
endorsed by the WHO.4 8–12 30 33 49
Our histopathological grade is defined by the sum of nest size
and budding activity scores, resulting in well differentiated (G1;
2–3 points), moderately differentiated (G2; 4–6 points) and
poorly differentiated (G3; 7 points) OSCC. In principle, one
small cell nest is enough for a tumour to be placed in a higher
nest size category even if all other nests in a given tumour are
on
17
December
2018
by
guest.
Protected
by
copyright.
http://jcp.bmj.com/
J
Clin
Pathol:
first
published
as
10.1136/jclinpath-2018-205454
on
8
December
2018.
Downloaded
from

Original article
Table 3 Cross tables of interobserver concordance between reviewers 1 and 2 as well as 1 and 3 before and after training for histomorphological
patterns cell nest size and budding activity and final grading
Cell nest size Reviewer 1
Large cell nests Intermediate cell nests Small cell nests Single cell infiltration Kappa
n % n % n % n %
Reviewer 2 Large cell nests 15 13.9 0 0.0 0 0.0 0 0.0 0.91
Intermediate cell nests 1 0.9 16 14.8 0 0.0 0 0.0
Small cell nests 0 0.0 2 1.9 26 24.1 1 0.9
Single cell infiltration 0 0.0 0 0.0 7 6.5 40 37.0
Before training Intermediate cell nests 4 3.7 9 8.3 2 1.9 0 0.0
Small cell nests 2 1.9 8 7.4 23 21.3 8 7.4
After training Intermediate cell nests 4 3.7 11 10.2 0 0.0 0 0.0
Small cell nests 0 0.0 3 2.8 22 20.4 7 6.5
Budding activity Reviewer 1
No budding activity Low budding activity High budding activity Kappa
n % n % n %
Reviewer 2 No budding activity 32 29.6 0 0.0 0 0.0 0.97
Low budding activity 1 0.9 49 45.4 0 0.0
High budding activity 0 0.0 1 0.9 25 23.1
Before training Low budding activity 11 10.2 33 30.6 3 2.8
After training Low budding activity 3 2.8 43 39.8 0 0.0
Grading Reviewer 1
G1 G2 G3 Kappa
n % n % n %
Reviewer 2 G1 32 29.6 0 0.0 0 0.0 0.97
G2 1 0.9 50 46.3 0 0.0
G3 0 0.0 1 0.9 24 22.2
Reviewer 3 G1 21 19.4 3 2.8 0 0.0 0.55
Before training G2 11 10.2 35 32.4 3 2.8
G3 1 0.9 13 12.0 21 19.4
Reviewer 3 G1 29 26.9 0 0.0 0 0.0 0.84
After training G2 3 2.8 44 40.7 0 0.0
G3 1 0.9 7 6.5 24 22.2
considerably larger. This strictly categorical approach has been
chosen to avoid subjectivity for this parameter as good as possible.
However, we acknowledge that there is still an element of subjec-
tivity, since it has to be decided by the pathologist whether rare
small ‘nests’ represent cross cut artefacts or ‘real’ tumour buds,
particularly in the context of a tumour morphology with almost
exclusively large tumour cell nests. Likely, most pathologists
would put very few small nests (unless they are unmistakeably
‘real’) in such a scenario in the ‘artefact’ category.
In a previous study,15
we showed a high prognostic impact of
this recently introduced histopathological grading system inde-
pendent of patient age, gender and tumour stage. Furthermore,
the proposed grading system showed a strong correlation with
pN-stage—the worse the grading, the higher the probability
of lymph node metastasis. In this context, it is interesting that
recently published studies suggest , that tumour budding in
particular might serve as a predictor of occult metastasis in in
patients with OSCC and cN0 necks, supporting a potential deci-
sion towards a neck dissection in these patients.50 51
As described above, a reliable histopathological grading
system is expected to be valid and be reproducible (above-men-
tioned criterion 2). Measurement of interobserver and intraob-
server agreement in general is performed by calculating Cohen’s
kappa. Altman considers a value of κ0.20 to represent poor
agreement, 0.21–0.40 as fair, 0.41–0.60 as moderate, 0.61–
0.80 as good and values of 0.81 or higher as very good agree-
ment.28
It has been proposed that a marker, on which treatment
schemes are based, should reach a kappa value of at least 0.41
for interobserver agreement,27 28
whereas others still assume a
value of 0.50 to be poor agreement.52
With a Cohen’s Kappa
of κ=0.97 between experienced pathologists, our proposed
grading system shows an almost perfect interobserver reliability.
One of the scoring expert pathologists (KJ) in the current study
was not involved in previous studies15 17 18
—suggesting that the
on
17
December
2018
by
guest.
Protected
by
copyright.
http://jcp.bmj.com/
J
Clin
Pathol:
first
published
as
10.1136/jclinpath-2018-205454
on
8
December
2018.
Downloaded
from

7
Original article
Figure 4 Number of cases with agreement/disagreement concerning final histopathological grading (G1–G3) of reviewers 1, 2 and 3 before and
after training. (A) Y-axis: reviewer 1; x-axis: reviewer 2; (B) y-axis: reviewer 1; x-axis: reviewer 3 before training; (C) y-axis: reviewer 1; x-axis: reviewer
3 after training.
implicated categories are clearly defined, rendering the grading
system simple, easy to assess and highly reliable. Intraobserver
reliability of the grading was also comparably high with κ=0.95.
Agreement on final grading was initially moderate with the
participating pathologist without expertise in head and neck
pathology. However, the consensus could be markedly improved
by training, emphasising the importance of training sessions for
pathologists with less diagnostic experience not yet accustomed
to the system. Detailed analysis of the contributing histopatho-
logical patterns tumour budding activity and cell nest size before
and after training revealed that the less experienced scorer
initially significantly overestimated the presence of budding
activity and small cell nest sizes/single cell infiltration—a point,
which should be considered in teaching sessions.
on
17
December
2018
by
guest.
Protected
by
copyright.
http://jcp.bmj.com/
J
Clin
Pathol:
first
published
as
10.1136/jclinpath-2018-205454
on
8
December
2018.
Downloaded
from

Original article
Table 4 Cross tables of intraobserver concordance of reviewer 2 for first and second evaluation of oral squamous cell carcinomas including
histomorphological patterns cell nest size and budding activity, grading score and final grading.
Cell nest size
Reviewer 2 first evaluation
Large cell nests Intermediate cell nests Small cell nests Single cell infiltration Kappa
n % n % n % n %
Reviewer 2
Large cell
nests 10 9.3 5 4.6 0 0.0 0 0.0 0.74
second
evaluation
Intermediate
cell nests 5 4.6 10 9.3 0 0.0 0 0.0
Small cell
nests 0 0.0 2 1.9 24 22.2 2 1.9
Single cell
infiltration 0 0.0 0 0.0 5 4.6 45 41.7
Budding Activity
no budding activity low budding activity high budding activity Kappa
n % n % n %
Reviewer 2
no budding
activity 30 27.8 0 0.0 0 0.0 0.97
second evaluation
low budding
activity 2 1.9 49 45.4 0 0.0
high budding
activity 0 0.0 1 0.9 26 24.1
Grading Score
Reviewer 2 first
evaluation
2 3 5 6 7 Kappa
n % n % n % n % n %
Reviewer 2 2 10 9.3 6 5.6 0 0.0 0 0.0 0 0.0 0.74
second
evaluation 3 5 4.6 9 8.3 0 0.0 0 0.0 0 0.0
5 0 0.0 2 1.9 22 20.4 3 2.8 0 0.0
6 0 0.0 0 0.0 5 4.6 20 18.5 0 0.0
7 0 0.0 0 0.0 0 0 1 0.9 25 23.1
Grading
G1 G2 G3 Kappa
n % n % n %
Reviewer 2 G1 30 27.8 0 0.0 0 0.0 0.97
second evaluation G2 2 1.9 50 46.3 0 0.0
G3 0 0.0 1 0.9 25 23.1
The kappa values achieved in the present study are higher than
expected when compared with other grading systems. Interob-
server reliability analysed for the MG model (including the
patterns keratinisation, mitotic count, pattern of invasion and
lymphocytic host response)11 29–32
resulted in Cohen’s kappa
values between 0.30 and 0.47. Regarding the single histopatho-
logical features, Sawair et al found moderate Kappa values for
keratinisation (0.48) and even worse ones for pattern of inva-
sion.33
Analysis of Kappa values for the pattern of invasion as
defined by the Royal College of Pathologists34
resulted in kappa
values between 0.43 and 0.58 in a study by Beggan et al,35
whereas Heerema et al found values between 0.25 and 0.5853
and Chang et al a value of 0.72.36
Interobserver agreement of the
HR model was good with κ=0.84.37
Data on interobserver and
intraobserver reliability of the Broder’s/WHO grading system is
available for penile SCC by Naumann et al54
and Gunia et al.55
In this entity, essentially the same grading criteria as in OSCC are
used. The authors both observed between fair and good interob-
server agreement (κ=0.378 to κ=0.692) and moderate to very
good intraobserver agreement (κ=0.575 to κ=0.942), which is
a surprisingly good result. However, Broder’s/WHO grading, as
mentioned above, is doubtlessly suboptimal in supplying inde-
pendent prognostic information.
Since we believe that an initial analysis of interobserver vari-
ation should focus on prototypical cases, we selected cases
from our previous study15
according to certain criteria. Thus,
we included only cases in which one fifth of the respective slide
was covered by carcinoma. In addition, we omitted those cases
which extended beyond the oral cavity or were p16 positive
on immunohistochemistry, to be fully sure, that we are dealing
with a ‘pure’ not human papilloma virus (HPV) related cohort
of prototypical oral SCC. Clearly, specifically in the scenario of
HPV associated non-keratinising tumours usually consisting of
larger tumour cell nests, follow on studies are clearly warranted.
In more general terms, additional retrospective multicentre
studies and/or prospective trials as well as concordance analysis
between biopsies and resection specimen and/or a correlation
of biopsy grading with presurgical clinical data for improve-
ment of therapeutic patient stratification (eg, whether or not
to perform a prophylactic neck dissection on a patient with
on
17
December
2018
by
guest.
Protected
by
copyright.
http://jcp.bmj.com/
J
Clin
Pathol:
first
published
as
10.1136/jclinpath-2018-205454
on
8
December
2018.
Downloaded
from

9
Original article
a clinically N-zero neck) are required to argue in favour of
a clinical implementation of this grading system into routine
diagnostics.
One limitation of our study is that the number of reviewers
comprised only three pathologists. Therefore, it is crucial to
conduct further studies to confirm our data. Nevertheless, the
current study strongly implies that the grading algorithm is
easy to apply and reliable with a high level of interobserver
and intraobserver agreement for both the histopathological
patterns cell nest size and budding activity as well as the final
grading.
We are convinced that the results presented here strengthen
the diagnostic certainty and clinical spread of our recently
introduced grading scheme for OSCC which has the potential
to build one cornerstone of a highly desirable future universal
novel grading algorithm for SCC of the upper aerodigestive
tract.
Take home messages
►
► Oral squamous cell carcinomas grading based on our recently
proposed novel scheme yields an excellent inter-reader and
intrareader agreement, supporting the suitability of this
grading system for routine pathological practice.
►
► High inter-reader and intrareader agreement suggests that
the implicated categories are clearly defined, rendering the
grading system simple, easy to assess and highly reliable.
►
► Grading performance of more inexperienced readers can
be markedly improved by a short training, emphasising the
importance of training sessions for pathology residents with
less diagnostic experience not yet accustomed to the system.
Handling editor Dr Cheok Soon Lee.
Contributors MB and WW designed this study and wrote this paper with
assistance from CB and KJ. MB, CB and KJ performed tissue analyses with assistance
from MJ, P-HK and KS. K-DW and AK helped gain clinical data, BH contributed to
statistical analysis.
Funding This study has been supported by the German Cancer Consortium (to
WW) and the Else-Kröner Fresenius-Stiftung (to MB).
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval Ethics Committee TU Munich, Faculty of Medicine.
Provenance and peer review Not commissioned; externally peer reviewed.
References
1. Bose P, Brockton NT, Dort JC. Head and neck cancer: from anatomy to biology. Int J
Cancer 20132013;133-23:2013–23.
2. Bagan JV, Scully C. Recent advances in oral oncology 2007: epidemiology,
aetiopathogenesis, diagnosis and prognostication. Oral Oncol 2008;44:103–8.
3. Barnes LL, Eveson JW, Reichart PA DS. Pathology and Genetics of Head and Neck
tumours. Lyon: IARC Press, 2005.
4. Müller S. Update from the 4th edition of the world health organization of head and
neck tumours: tumours of the oral cavity and mobile tongue. Head Neck Pathol
2017;11:33–40.
5. Broders A. Squamous cell cancer of the lip: a study of five hundred and thirty-seven
cases. JAMA Otolaryngol Head Neck Surg 1920;74:656–64.
6. Gospodarowicz MK, Brierley JD,Wittekind C. TNM classification of malignant tumours.
John Wiley Sons, 2017.
7. Barnes L. Pathology and genetics of head and neck tumours. IARC, 2005.
8. Anneroth G, Hansen LS, Silverman S. Malignancy grading in oral squamous cell
carcinoma. I. Squamous cell carcinoma of the tongue and floor of mouth: histologic
grading in the clinical evaluation. J Oral Pathol 1986;15:162–8.
9. Anneroth G, Batsakis J, Luna M. Review of the literature and a recommended
system of malignancy grading in oral squamous cell carcinomas. Scand J Dent Res
1987;95:229–49.

10. Brandwein-Gensler M,Teixeira MS, Lewis CM, et al. Oral squamous cell carcinoma:
histologic risk assessment, but not margin status, is strongly predictive of local
disease-free and overall survival. Am J Surg Pathol 2005;29:167–78.

11. Bryne M, Koppang HS, Lilleng R, et al. Malignancy grading of the deep invasive
margins of oral squamous cell carcinomas has high prognostic value. J Pathol
1992;166:375–81.

12. Lindenblatt RC, Martinez GL, Silva LE, et al. Oral squamous cell carcinoma grading
systems--analysis of the best survival predictor. J Oral Pathol Med 2012;41:34–9.

13. Takes RP, Rinaldo A, Silver CE, et al. Future of the TNM classification and staging
system in head and neck cancer. Head Neck 2010;32:1693–711.

14. Aydil U, Duvvuri U, Kizil Y, et al.Tumour-node-metastasis staging of human
papillomavirus negative upper aerodigestive tract cancers: a critical appraisal. J
Laryngol Otol 2015;129:1148–55.

15. Boxberg M, Jesinghaus M, Dorfner C, et al.Tumour budding activity and cell nest size
determine patient outcome in oral squamous cell carcinoma: proposal for an adjusted
grading system. Histopathology 2017;70:1125–37.

16. Jesinghaus M, Strehl J, Boxberg M, et al. Introducing a novel highly prognostic
grading scheme based on tumour budding and cell nest size for squamous cell
carcinoma of the uterine cervix. J Pathol Clin Res 2018;4:93–102.

17. Jesinghaus M, Boxberg M, Konukiewitz B, et al.A novel grading system based
on tumor budding and cell nest size is a strong predictor of patient outcome in
esophageal squamous cell carcinoma. Am J Surg Pathol 2017;41:1112–20.

18. Weichert W, Kossakowski C, Harms A, et al. Proposal of a prognostically
relevant grading scheme for pulmonary squamous cell carcinoma. Eur Respir J
2016;47:938–46.

19. Kadota K, Nitadori J,Woo KM, et al. Comprehensive pathological analyses in
lung squamous cell carcinoma: single cell invasion, nuclear diameter, and tumor
budding are independent prognostic factors for worse outcomes. J Thorac Oncol
2014;9:1126–39.

20. Horcic M, Koelzer VH, Karamitopoulou E, et al.Tumor budding score based on 10
high-power fields is a promising basis for a standardized prognostic scoring system in
stage II colorectal cancer. Hum Pathol 2013;44:697–705.

21. Karamitopoulou E, Zlobec I, Kölzer V, et al. Proposal for a 10-high-power-fields
scoring method for the assessment of tumor budding in colorectal cancer. Mod Pathol
2013;26:295–301.

22. Ueno H, Murphy J, Jass JR, et al.Tumour ’budding’ as an index to estimate the
potential of aggressiveness in rectal cancer. Histopathology 2002;40:127–32.

23. Kemi N, Eskuri M, Ikäläinen J, et al.Tumor budding and prognosis in gastric
adenocarcinoma. Am J Surg Pathol 2018:1.

24. Li X,Wei B, Sonmez C, et al. High tumor budding count is associated with adverse
clinicopathologic features and poor prognosis in breast carcinoma. Hum Pathol
2017;66:222–9.
25. Damjanov I. History and general aspects of tumor grading. Cancer Grading Manual:
Springer, 2013: 1–7.

26. Cross SS. Grading and scoring in histopathology. Histopathology 1998;33:99–106.

27. Fleming KA. Evidence-based pathology. J Pathol 1996;179:127–8.
28 Altman DG. Practical Statistics for Medical Research. New York: Chapman and Hall/
CRC, 1990.

29. Bryne M, Nielsen K, Koppang HS, et al. Reproducibility of two malignancy grading
systems with reportedly prognostic value for oral cancer patients. J Oral Pathol Med
1991;20:369–72.

30. Bryne M, Nielsen K, Koppang HS, et al. Grading of nuclear pleomorphism in oral
carcinomas. Higher prognostic value than stereological assessment of nuclear volume.
APMIS 1991;99:333–9.

31. Bryne M, Koppang HS, Lilleng R, et al. New malignancy grading is a better prognostic
indicator than broders’ grading in oral squamous cell carcinomas. J Oral Pathol Med
1989;18:432–7.

32. Piffkò J, Bànkfalvi A, Ofner D, et al. Prognostic value of histobiological factors
(malignancy grading and AgNOR content) assessed at the invasive tumour front of
oral squamous cell carcinomas. Br J Cancer 1997;75:1543–6.

33. Sawair FA, Irwin CR, Gordon DJ, et al. Invasive front grading: reliability and usefulness
in the management of oral squamous cell carcinoma. J Oral Pathol Med 2003;32:1–9.
34. Helliwell T,Woolgar J. Dataset for histopathology reporting of mucosal malignancies
of the pharynx. London:The Royal College of Pathologists, 2013.

35. Beggan C, Fives C, O’Leary G, et al. Pattern of invasion and lymphovascular invasion
in squamous cell carcinoma of the floor of the mouth: an interobserver variability
study. Histopathology 2016;69:914–20.

36. Chang YC, Nieh S, Chen SF, et al. Invasive pattern grading score designed as an
independent prognostic indicator in oral squamous cell carcinoma. Histopathology
2010;57:295–303.

37. Rodrigues PC, Miguel MC, Bagordakis E, et al. Clinicopathological prognostic factors
of oral tongue squamous cell carcinoma: a retrospective study of 202 cases. Int J Oral
Maxillofac Surg 2014;43:795–801.

38. Wolff K-D, Follmann M, Nast A.The diagnosis and treatment of oral cavity cancer.
Deutsches Ärzteblatt International 2012;109:829.

39. Wulff HR. Rational diagnosis and treatment. J Med Philos 1986;11:123–34.

40. Jubel A, Faymonville C,Andermahr J, et al. [Conventional x-rays of ankle joint fractures
in older patients are not always predictive]. Z Orthop Unfall 2017;155:45–51.
on
17
December
2018
by
guest.
Protected
by
copyright.
http://jcp.bmj.com/
J
Clin
Pathol:
first
published
as
10.1136/jclinpath-2018-205454
on
8
December
2018.
Downloaded
from

Original article

41. Almangush A, Coletta RD, Bello IO, et al.A simple novel prognostic model for early
stage oral tongue cancer. Int J Oral Maxillofac Surg 2015;44:143–50.

42. Almangush A, Salo T, Hagström J, et al.Tumour budding in head and neck squamous
cell carcinoma - a systematic review. Histopathology 2014;65:587–94.

43. Sawazaki-Calone I, Rangel A, Bueno AG, et al.The prognostic value of
histopathological grading systems in oral squamous cell carcinomas. Oral Dis
2015;21:755–61.

44. Wang C, Huang H, Huang Z, et al.Tumor budding correlates with poor prognosis and
epithelial-mesenchymal transition in tongue squamous cell carcinoma. J Oral Pathol
Med 2011;40:545–51.

45. Attramadal CG, Kumar S, Boysen ME, et al.Tumor budding, EMT and cancer stem cells
in T1-2/N0 oral squamous cell carcinomas. Anticancer Res
2015;35:6111–20.

46. Dongre A, Rashidian M, Reinhardt F, et al. Epithelial-to-mesenchymal transition
contributes to immunosuppression in breast carcinomas. Cancer Res
2017;77:3982–9.

47. Gurzu S, Silveanu C, Fetyko A, et al. Systematic review of the old and new concepts
in the epithelial-mesenchymal transition of colorectal cancer. World J Gastroenterol
2016;22:6764–75.

48. Niwa Y,Yamada S, Koike M, et al. Epithelial to mesenchymal transition correlates with
tumor budding and predicts prognosis in esophageal squamous cell carcinoma. J Surg
Oncol 2014;110:764–9.

49. Graflund M, Sorbe B, Hussein A, et al.The prognostic value of histopathologic grading
parameters and microvessel density in patients with early squamous cell carcinoma of
the uterine cervix. Int J Gynecol Cancer 2002;12:32–41.

50. Sakata J,Yamana K,Yoshida R, et al.Tumor budding as a novel predictor of occult
metastasis in cT2N0 tongue squamous cell carcinoma. Hum Pathol 2018;76:1–8.

51. Seki M, Sano T,Yokoo S, et al.Tumour budding evaluated in biopsy specimens is a
useful predictor of prognosis in patients with cN0 early stage oral squamous cell
carcinoma. Histopathology 2017;70:869–79.

52. Svanholm H, Starklint H, Gundersen HJ, et al. Reproducibility of histomorphologic
diagnoses with special reference to the kappa statistic. APMIS 1989;97:689–98.

53. Heerema MG, Melchers LJ, Roodenburg JL, et al. Reproducibility and prognostic
value of pattern of invasion scoring in low-stage oral squamous cell carcinoma.
Histopathology 2016;68:388–97.

54. Naumann CM,Alkatout I, Hamann MF, et al. Interobserver variation in grading and
staging of squamous cell carcinoma of the penis in relation to the clinical outcome.
BJU Int 2009;103:1660–5.

55. Gunia S, Burger M, Hakenberg OW, et al. Inherent grading characteristics of individual
pathologists contribute to clinically and prognostically relevant interobserver
discordance concerning broders’ grading of penile squamous cell carcinomas. Urol Int
2013;90:207–13.
on
17
December
2018
by
guest.
Protected
by
copyright.
http://jcp.bmj.com/
J
Clin
Pathol:
first
published
as
10.1136/jclinpath-2018-205454
on
8
December
2018.
Downloaded
from

New grading system for SCC.pdf

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to New grading system for SCC.pdf

Similar to New grading system for SCC.pdf (20)

Recently uploaded

Recently uploaded (20)

New grading system for SCC.pdf