2. Breast Cancer

Breast cancer – one-breath summary

Commonest cancer in women • Found by mammography, confirmed by triple assessment • Most have lumpectomy + radiotherapy • Modern RT = 26 Gy in 5 fractions over 1 week

Breast cancer – WHO (risk factors)

• Female, older age • BRCA1 / BRCA2 genes, family history • Long oestrogen exposure:    ◦ Early periods, late menopause    ◦ No children    ◦ HRT • Obesity, alcohol • Chest RT when young

Breast cancer – WHAT (histology)

• DCIS = Ductal Carcinoma In Situ (pre-invasive, calcium specks) • Invasive ductal carcinoma (~75%) • Invasive lobular carcinoma (multifocal, MRI helpful) • Always test for:    ◦ ER / PR (hormone receptors)    ◦ HER2

Breast cancer – molecular subtypes

• Luminal A → ER/PR+, HER2−, slow • Luminal B → ER+, faster (high Ki-67) ± HER2 • HER2-enriched • Triple negative → ER−, PR−, HER2− (linked to BRCA1, aggressive)

Breast cancer – SIGNS

• Hard, painless lump • Skin dimpling ("orange peel" / peau d'orange) • Nipple pulled in or discharge • Lump in the armpit (axillary nodes) • Red swollen breast = inflammatory (T4d)

Breast cancer – SCANS

• Mammography → spiky mass, micro-calcifications (scored BI-RADS) • Ultrasound → young/dense breasts, armpit nodes • MRI → BRCA carriers, lobular cancer • Triple assessment = examination + imaging + core biopsy • Sentinel node scan (Tc-99m) → finds first node to remove • Bone scan or PET/CT if advanced

What is BI-RADS?

Mammography scoring 0–6 • 0 = incomplete • 1 = negative • 2 = benign • 3 = probably benign → short follow-up • 4 = suspicious → biopsy • 5 = highly likely cancer (≥95%) • 6 = proven cancer

Breast cancer – STAGE (T sizes)

• T1 ≤ 2 cm • T2 2–5 cm • T3 > 5 cm • T4 chest wall or skin    ◦ T4d = inflammatory

Breast cancer – TREAT

• Lumpectomy + RT (as good as mastectomy) • Sentinel lymph node biopsy • Then depending on type:    ◦ Hormone tablets (tamoxifen / aromatase inhibitor) if ER+    ◦ Anti-HER2 (trastuzumab) if HER2+    ◦ Chemotherapy • Advanced → mastectomy + chest wall RT

DOSE: Whole breast RT

• Modern UK → 26 Gy / 5 (one week, FAST-Forward) • Also standard → 40 Gy / 15 • Old conventional → 50 Gy / 25

DOSE: Tumour bed boost

• Extra 10–16 Gy to where the lump was • For: young patients, high grade, positive margin • Cost: more fibrosis

DOSE: After mastectomy (chest wall)

• 26 Gy / 5 or 40 Gy / 15

Breast RT – side effects

• Red skin, peeling skin • Breast hardening (fibrosis) • Arm swelling (lymphoedema) • Heart damage (left side) • Lung pneumonitis (rare)

Breast cancer – dose memory hook

26 in 5, 40 in 15, 50 in 25 = new, standard,