2. Patro, et al.: Radical brachytherapy for early-stage external auditory canal cancer
50 50 Journal of Current Oncology ¦ Volume 2 ¦ Issue 2 ¦ July-December 2019
Mono-institutional Initial Experience
We selected the plastic earbud [Figure 1], which is commonly
available in the market. It has an approximate length
of 5 cm and inner diameter of 3 mm, whose dimensions
are comparable with either the stainless steel needles
[Figures 2 and 3] or nylon catheters available for remote-
after-loading HDR Ir192
. Plastic earbuds are atraumatic
in nature in comparison with stainless steel needles. An
interstitial one-end blind needle with a length of 10 cm is
inserted into an earbud and the assembly is inserted into
the EAC. The distal open end of the plastic earbud is
sealed off by wax, so that the chance of penetrating needle
injury is nullified in the case of needle movement during
the procedure. The position of the plastic earbud in EAC
can further be stabilized using an earpiece of stethoscope
[Figure 4]. This combined arrangement of interstitial
needle stethoscope earpiece along with the plastic earbud
ensures proper reproducible positioning of the radioactive
source during the dwell-time as well as patient comfort,
hence making this arrangement as an effective radioactive
source carrier prosthesis [Figure 5]. After obtaining an
informed consent, we selected a volunteer for an initial
feasibility study. Computed tomographic (CT) simulation
Figure 2: Applicator and dosimetry
Figure 3: Ear bud and applicator attached
Figure 4: Ear bud and applicator attached and stethoscope piece
connected
Figure 5: The total piece inside ear canal
Figure 1: Structure of the applicator
[Downloaded free from http://www.journalofcurrentoncology.org on Wednesday, January 8, 2020, IP: 10.232.74.23]
3. Patro, et al.: Radical brachytherapy for early-stage external auditory canal cancer
Journal of Current Oncology ¦ Volume 2 ¦ Issue 2 ¦ July-December 2019 51
scan of slice thickness of 1 mm with marked dummy
radioactive wire inside the source carrier prosthesis of the
temporal bone with 5 cm margin superoinferiorly. A plan
was generated followed by initial dosimetric analysis using
a treatment planning system (Oncentra, Elekta). A linear
array of radioactive source position was activated for
desired length and the plan was optimized. The dose
was prescribed at 5 mm off-axis. If the gross tumor
volume (GTV) is appreciated, a clinical target volume
can be contoured with a margin of 1 cm around the GTV
sparing the brain and tympanic membrane [Figure 6].
The high-dose sleeves in the surface of the applicator can
be dampened by use of wax in the surface of the plastic
earbud.
Inters��al needle
connected to the transfer
tube
Wax coa�ng 5mm
Plas�c ear bud
Co�on plug
Stethoscope ear plug
Ear-bud brachytherapy assembly
Diagram by
dr p s bhattacharyya
Discussion
Tumors of EAC are rare and constitute 0.2% of all
head and neck squamous cell carcinoma (HNSCC).[1,2]
Of these the majority are SCC (85%). A tumor, node,
metastasis staging system is most commonly followed,
which includes histopathologic extent of tumor invasion
and radiological evaluation.[3]
The contemporary
treatment options include either radical surgery with or
without postoperative adjuvant radio (chemo) therapy or
radical radio (chemo) therapy depending upon the stage.
Radical surgery followed by postoperative adjuvant
radio (chemo) therapy is generally used in advanced
disease.[4-7]
Radical surgery includes wide excision of
disease along with removal of middle and/or external
ear results in poor cosmetic and functional outcomes. In
contrast, radical RT that includes either external beam
radiotherapy (EBRT), BT or sequentially combined can
be an alternative with comparable local tumor control
rate and acceptable cosmesis, especially in early-stage
disease (without soft-tissue extension or bony erosion),
although there is paucity of literatures to support this.[8-
11]
Although small-volume lesions can well be treated
with BT alone, there are some technical challenges.
Here, we attempt to deliver a radical BT dose using a
unique source carrier prosthesis that consists of easily
available plastic earbud stabilized with the earpiece of
the stethoscope. It is a dosimetric feasibility study and we
did not treat the patient (volunteer). He was comfortable
throughout the procedure as well as physics-dosimetry to
above arrangement was satisfactory. Our proposed dose
schedule is like other SCC 3 Gy per fraction twice daily
with 6-h gap and biological equivalent dose about more
than 60 Gy over a period of 10 days. The actual dose
is mostly for other SCC. There are no dose criteria for
these organ-at-risk (OAR) structures such as tympanic
membrane and cartilages. When we treat with external
RT, we do not give constraints. As a principle, we should
follow as low as reasonably achievable (ALARA) for
these OAR structures. This is a feasibility study and
in other literature late effects are not mentioned and
reported. Stethoscope ear piece we taken as readymade. It
can be performed also with wax, but it needs expertise to
make it. The stability of this bud and catheter definitely
earbud is more stable. Other things are earbud is cheaper
and easily available.
Conclusion
The combination of commercially available plastic earbud
along with soft flexible earpiece of stethoscope of a 10-cm
17-gauge interstitial needle can be a radioactive source
carrier applicator prosthesis for radical BT of early-stage
SCC-EAC. However, it requires further validations. It is
an attempt to put a bit of innovation into practice for
very early lesions of the EAC confine to the mucosa or
cartilage away from the tympanic membrane for patients
medically inoperable and reluctant for such debilitating
surgery.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References
1. Arriaga M, Hirsch BE, Kamerer DB, Myers EN. Squamous cell
carcinoma of the external auditory meatus (canal). Otolaryngol
Head Neck Surg 1989;101:330-7.
2. Shih L, Crabtree JA. Carcinoma of the external auditory canal: An
update. Laryngoscope 1990;100:1215-8.Figure 6: Dosimetry
[Downloaded free from http://www.journalofcurrentoncology.org on Wednesday, January 8, 2020, IP: 10.232.74.23]
4. Patro, et al.: Radical brachytherapy for early-stage external auditory canal cancer
52 52 Journal of Current Oncology ¦ Volume 2 ¦ Issue 2 ¦ July-December 2019
3. Arriaga M, Curtin H, Takahashi H, Hirsch BE, Kamerer DB.
Staging proposal for external auditory meatus carcinoma based
on preoperative clinical examination and computed tomography
findings. Ann Otol Rhinol Laryngol 1990;99:714-21.
4. Conley JJ,Novack AJ.Thesurgicaltreatmentof malignanttumorsof the
ear and temporal bone. Part I. AMA Arch Otolaryngol 1960;71:635-52.
5. Prasad S, Janecka IP. Efficacy of surgical treatments for squamous
cell carcinoma of the temporal bone: A literature review. Otolaryngol
Head Neck Surg 1994;110:270-80.
6. Gabriele P,Magnano M,Albera R,Canale G,Redda MG,Krengli M,
et al. Carcinoma of the external auditory meatus and middle ear:
Results of the treatment of 28 cases. Tumori 1994;80:40-3.
7. Paaske PB, Witten J, Schwer S, Hansen HS. Results in treatment of
carcinoma of the external auditory canal and middle ear. Cancer
1987;59:156-60.
8. Korzeniowski S, Pszon J. The results of radiotherapy of cancer of
the middle ear. Int J Radiat Oncol Biol Phys 1990;18:631-3.
9. Wang CC. Radiation therapy in the management of carcinoma
of the external auditory canal, middle ear, or mastoid. Radiology
1975;116:713-5.
10. Waldemar E, Sørensen T, Bretlau P, Hansen HS. Cancer in the
middle ear and the auditory canal. Ugeskr Laeger 1995;157:2139-42.
11. Stell PM, McCormick MS. Carcinoma of the external auditory
meatus and middle ear. J Laryngol Otol 1985;99:847-50.
[Downloaded free from http://www.journalofcurrentoncology.org on Wednesday, January 8, 2020, IP: 10.232.74.23]