BREAST <3

Question 1

Criteria for Boost; benefit and risks.

Answer 1

Age under 50, margin <2mm for DCIS, for IDC at PMH you can say margin of 10mm), high grade (grade 3)

Benefit: decrease LR by 4%, severe fibrosis 2% vs 4%

Note: in DCIS, if margins are less than 2mm, should go for re-excision: doubles the risk of ipsilateral breast cancer recurrence

Question 2

Breast cancer histologic types with more favourable prognosis than IDC/lobular:

Answer 2

Tubular, mucinous, medullary, cribriform, invasive papillary

Less favourable prognosis: micropapillary!!!

Question 3

neoadjuvant chemo regimen

Answer 3

ddAC-taxol
(adriamycin, cyclophosphamide, paclitaxel):
AC x 4 (q2w) followed by T x 4 (q2w)

If HER2+v, add herceptin (trastuzumab) to T (AC -> T + trastuzumab)

TNBC: pembo + carbo/paclitaxel followed by pembro + AC

Hormone therapy for all ER/PR positive patients:
- Tamoxifen x 5yr if pre-meno
- Anastrazole x 5yr if post-meno

Question 4

Systemic therapy for metastatic

Answer 4

1) bone mets present: add denosumab or ZA
2) ER positive: AI + palbociclib (CDK4/6i); add trastuzumab if HER2+
3) TNBC: pembro + paclitaxel

Question 5

Who can be considered for omission of RT after lumpectomy (Lumin-A trial, Whelan)

Answer 5

• ≥55yrs , T1N0, G1-2, ER/PR+, HER2-, Ki67 <13%; receiving adjuvant endocrine therapy.

Question 6

APBI: who can get (ASTRO guidelines). And volumes.

Answer 6

Early stage invasive breast cancer or DCIS with all of the following:
- Grade 1 or 2 disease
- Age ≥ 40
- ER positive histology
- Tumor size ≤2cm

Volumes:
- CTV: tumor bed + 1cm, carved 3mm from skin, carved off pec. PTV 1cm.

Not recommended if: positive margins, positive LN, BRCA1/2 mutation (remember clinic with Danny), LVSI, lobular histology

Question 7

What is oncotype test and what is the score for systemic therapy?

Answer 7

It is a 21gene assay testFor all hormone positive, HER2- patients to identify those with a risk of recurrence. They must get systemic endocrine therapy afterwards!

Perform if T1b (5.001mm-1.0cm)

Score:
post-meno: ≥26: adjuvant chemo followed by endocrine

Pre-meno: same as above, consider for 16-25.

Question 8

Breast fields
a) tangents
b) 4 field

Answer 8

a):
sup: inf head of clavicle (inf head of humeral head for high tangents in the case of WBRT + Axilla Lv I and II.
inf: 2cm below inframammary fold
medial: mid-sternum (3cm past if wide tangents when doing 4-field RNI to include IMNs)
lateral: mid axillary line
ant: 2cm beyond skin

***post:

b):
inf: inf of clavicle head matching the breast tangent field
sup: inferior cricoid
lateral: to surgical neck of humerus
medial: pedicles of thoracic vertebrae

Question 9

OARs

Answer 9

2 field (breast alone)
- unilateral lung: V17.5< 15%
- Contralateral lung V5Gy < 10%
- Heart V25Gy < 10% left side, 2% right side
- Heart mean dose < 2Gy

4 field:
- UNilateral lung V17.5Gy < 30%
- Contralateral lung V5Gy < 10%
- Heart V25Gy < 10% left side, 2% right side
- Heart mean dose < 3Gy

Question 10

Plan eval: Coverage

Answer 10

Breast 95% of prescribed dose should cover the entire breast (>99%), avoid hotspot above 108%, with 95% of the surgical cavity covered by the 95% isodose line.
Axilla: PTV V90%> 90%
Supraclavicular field: PTV V90%>90%, avoid hotspot above 105%