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A 52-year-old woman has screening mammography showing a 2 cm cluster of pleomorphic microcalcifications in the upper outer quadrant of the right breast. Stereotactic core biopsy confirms DCIS, intermediate nuclear grade, ER-positive. No mass lesion.
Questions
a) What is the diagnosis and stage? (2 marks)
Ductal carcinoma in situ (DCIS) — non-invasive breast cancer confined to ducts (basement membrane intact). Stage 0 (Tis, N0, M0). ER-positive means tamoxifen is an option.
b) What are the surgical options? (3 marks)
- Breast-conserving surgery (WLE) with clear margins (at least 2 mm) + whole-breast radiotherapy — standard for unicentric DCIS under 4 cm
- Mastectomy (with SLNB) — for large (over 4 cm), multicentric DCIS, or patient preference
- Tamoxifen for 5 years (ER-positive) — reduces ipsilateral and contralateral recurrence
c) What is the role of radiotherapy after breast-conserving surgery? (2 marks)
Radiotherapy reduces local recurrence by approximately 50% after WLE for DCIS (NSABP B-17 trial). Recommended for all DCIS treated with BCS except very low-risk (small, low-grade, widely excised — VNPI 3-4).
d) What is the prognosis? (3 marks)
Breast cancer-specific survival: 97-99% at 10 years (DCIS is highly curable). Local recurrence after BCS+RT: 10-15% at 10 years; approximately half of recurrences are invasive carcinoma. Local recurrence after mastectomy: under 2%.