The document presents a consensus on anatomical boundaries for breast cancer radiation therapy planning, focusing on contour definitions for breast, chest wall, and nodal volumes. It includes illustrative cases of different breast cancer stages and outlines guidelines for marking and utilizing anatomical references during treatment. The aim is to standardize radiation therapy planning to improve treatment precision and outcomes.

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Breast Cancer Atlas for Radiation
Therapy Planning:
Consensus Definitions

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2
Collaborators
Julia White1, An Tai1, Douglas Arthur2, Thomas Buchholz3,
Shannon MacDonald4, Lawrence Marks5, Lori Pierce6,
Abraham Recht7, Rachel Rabinovitch8, Alphonse Taghian4,
Frank Vicini9, Wendy Woodward3, X. Allen Li1
1Medical College of Wisconsin, 2Virginia Commonwealth University, 3M.D.
Anderson Cancer Center, 4Massachusetts General Hospital, 5University of North
Carolina, 6University of Michigan, 7Beth Israel Deaconess Medical Center
Hospital, 8University of Colorado, 9 William Beaumont Hospital

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Content
→ Overlying principles: slides 4 - 6
→ Consensus definitions of anatomical boundaries:
slides 7 - 12
→ Illustrative cases:
– A: Stage I intact post-lumpectomy left breast
(slides 13 - 30)
– B: Stage III post-mastectomy left breast
(slides 32 - 51)
– C: Stage III intact post-lumpectomy right
breast (slides 54 - 71)
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Overlying principles: Breast Contour
Breast CTV:
– Considers referenced clinical breast at time of
CT
– Includes the apparent CT glandular breast
tissue
– Incorporates consensus definitions of
anatomical borders (see table)
– Includes the lumpectomy CTV
Lumpectomy GTV: Includes seroma and surgical
clips when present
4

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Overlying principles: Chestwall Contour
Chestwall CTV:
– Considers referenced clinical chestwall at time
of CT
– Incorporates consensus definitions of
anatomical borders (see table)
– Includes the mastectomy scar (may not be feasible
for occasional cases where the scar extends beyond the typical
borders of the chestwall)
5

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Overlying principles: Nodal volumes
Regional nodal CTV:
– Nodal volumes contoured for targeting will
depend on the specific clinical case
– Considers consensus definitions of anatomical
borders (see table)
– The three levels of the axilla can overlap
caudal to cranial
– “Axillary apex” was considered level III
of the axilla
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Breast and Chestwall Contour: Anatomical Boundaries
Cranial Caudal Anterior Posterior Lateral Medial
Breast1
Clinical
Reference
+ Second
rib
insertiona
Clinical
reference +
loss of CT
apparent
breast
Skin
Excludes
pectoralis
muscles,
chestwall
muscles, ribs
Clinical
Reference +
mid axillary
line typically,
excludes
latissimus
(Lat.) dorsi m.
b
Sternal-
rib
junction c
Breast +
Chestwall2 Same Same Same
Includes
pectoralis
muscles,
chestwall
muscles, ribs
Same Same
Chestwall3
Caudal
border of
the
clavicle
head
Clinical
reference+
loss of CT
apparent
contralateral
breast
Skin
Rib-pleural
interface.
(Includes
pectoralis
muscles,
chestwall
muscles, ribs)
Clinical
Reference/
mid axillary
line typically,
excludes
lattismus dorsi
m a
Sternal-
rib
junction b
7

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Contouring Comments:
Breast and Chestwall
1. Breast: After appropriate lumpectomy for breast only
treatment
a. Cranial border is highly variable depending on breast
size and patient position. The lateral aspect can be
more cranial then the medial aspect depending on
breast shape and patient position.
b. Lateral border is highly variable depending on breast
size and amount of ptosis.
c. Medial border is highly variable depending on breast
size and amount of ptosis. Clinical reference needs to
be taken into account. Should not cross midline.
8

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Contouring Comments:
Breast and Chestwall
2. Breast-Chestwall: CTV after appropriate lumpectomy for more
locally advanced cases includes those:
– With clinical stage IIb, III who receive neoadjuvant
chemotherapy and lumpectomy
– Who have sufficient risk disease to require post-mastectomy
radiation had mastectomy done
3. Chestwall: CTV after appropriate mastectomy:
a. Lateral border meant to estimate the lateral border of the previous
breast. Typically extends beyond the lateral edge of the
pectoralis muscles but excluded the latissimus dorsi muscle
b. Clinical reference marks need to be taken into account. The
chestwall typically should not cross midline. Medial extent of
mastectomy scar should typically be included 9

10. Regional Nodal Contours: Anatomical Boundaries
Cranial Caudal Anterior Posterior Lateral Medial
Supra-
clavicular
Caudal to
the cricoid
cartilage
Junction of
brachioceph.-
axillary vns./
caudal edge
clavicle head a
Sternocleido
mastoid
(SCM)
muscle (m.)
Anterior aspect
of the scalene
m.
Cranial: lateral
edge of SCM
m.
Caudal:
junction 1st rib-
clavicle
Excludes
thyroid and
trachea
Axilla-
Level I
Axillary
vessels cross
lateral edge of
Pec. Minor m.
Pectoralis
(Pec.) major
muscle insert
into ribs b
Plane defined
by: anterior
surface of Pec.
Maj. m. and
Lat. Dorsi m.
Anterior
surface of
subscapularis
m.
Medial
border of lat.
dorsi m.
Lateral
border of
Pec. minor
m.
Axilla-
level II
Axillary
vessels cross
medial edge
of Pec. Minor
m.
Axillary vessels
cross lateral
edge of Pec.
Minor m.
c
Anterior
surface Pec.
Minor m.
Ribs and
intercostal
muscles
Lateral
border of
Pec. Minor
m.
Medial
border of
Pec. Minor
m.
Axilla-
level III
Pec. Minor
m. insert on
cricoid
Axillary vessels
cross medial
edge of Pec.
Minor m. d.
Posterior
surface Pec.
Major m.
Ribs and
intercostal
muscles
Medial
border of
Pec. Minor
m.
Thoracic
inlet
Internal
mammary
Superior
aspect of the
medial 1st rib.
Cranial aspect
of the 4th rib
- e. - e. - e. - e.

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Contouring Comments:
Regional Nodal Volumes
a. Supraclavicular caudal border meant to approximate the
superior aspect of the breast/ chestwall field border
b. Axillary level I caudal border is clinically at the base of
the anterior axillary line
c. Axillary level II caudal border is the same as the cranial
border of level 1
d. Axillary level III caudal border is the same as the
cranial border of level II
e. Internal Mammary lymph nodes: encompass the
internal mammary/ thoracic vessels
11

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Case A- Intact post lumpectomy breast
• Stage I ( T1c, N0, M0) Left breast cancer
• Surgery: Lumpectomy and sentinel node biopsy
• Radiation: Breast
• Six surgical clips placed at lumpectomy site
• External markers placed at time of CT:
– BB at AP set-up point
– 4 wire markers for clinical estimate of cranial, caudal,
medial, and lateral extent of anticipated tangents
– Wire extending from 9-3 o’clock around the infra-
mammary fold
– Wire over the lumpectomy scar
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• Stage IIIB (T-3, N-3, M-0) left breast cancer, tumor size
7 cm, 11/15 nodes positive
• Surgery: total mastectomy and axillary done dissection
• Radiation: chestwall +
Case B: Post-mastectomy, Stage III
regional lymph nodes
• External wires present on CT:
– Wire on mastectomy scar
– BB on AP set-point at clinically estimated level of the
match for the supraclavicular + axilla with the
chestwall + IMC fields
– Wires at lateral and inferior clinically estimated extent
of the chestwall 31

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Case C: Stage III- Intact breast
post lumpectomy
• Stage IIIA (T-2, N-2, M-0) right breast cancer, tumor size 3 cm,
4/18 nodes positive
• Surgery: Lumpectomy and axillary node dissection
• Radiation: Breast, chestwall + regional lymph nodes
• External wires present on CT:
– Wire on lumpectomy scar
– BB on AP set-point at clinically estimated level of the match for
the supraclavicular + axilla with the chestwall + IMC fields
– Wire extending from 9-3 o’clock around the infra-mammary fold
– Wires at lateral and inferior clinically estimated extent of the
chestwall
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