New DCIS on core biopsy — upgrade, margins, radiation, axilla, endocrine choice and the patient who wants surveillance

Examiner prompts with model answers

Upgrade first — the number that opens consent. About one in four core-biopsy DCIS diagnoses (25.9% across 52 studies) prove invasive at excision — so the excision may change the diagnosis, and the plan must survive that change.^[10]

Grade the predictors, not just the diagnosis. 14-gauge devices, high grade, size over 20 mm, BI-RADS 4-5, mass pattern and palpability raise upgrade risk — read her mammogram and core details as a probability, not a label.^[10]

Margins — the 2 mm answer with its evidence base. Excise to 2 mm with whole-breast irradiation: negative margins halve recurrence against ink on DCIS, 2 mm minimises it, wider adds nothing — from 20 studies and 7883 patients, with fewer re-excisions as the service dividend.^[9]

Radiation — halves recurrence, never survival. B-17 cut invasive ipsilateral tumours 13.4 to 3.9% with 50 Gy; EORTC at 15 years lifted recurrence-free 69 to 82% with no survival difference — consent local control, and name the invasive-recurrence survival penalty (BCSS HR 17.66) as the reason control still matters.^[1][4]

Axilla by operation. Conservation means no sentinel biopsy; mastectomy means offer it — ASCO reaffirmed without change, the Dutch cohort validates omission (2% metastases in pure DCIS, delayed biopsy retrievable), and no pure-DCIS patient in Alberta had a positive sentinel node.^[11][12]

Endocrine choice in receptor-positive disease. Tamoxifen 20 mg daily for 5 years is the default; anastrozole 1 mg daily is the non-inferior alternative (67 versus 77 recurrences, superiority not shown) for the postmenopausal woman with a tamoxifen contraindication — chosen on toxicity, not efficacy.^[8]

The surveillance question — fenced, not dismissed. COMET randomised low-risk hormone-receptor-positive grade 1-2 DCIS to 6-monthly monitoring versus surgery: 4.2 versus 5.9% invasive at 2 years, non-inferior — but median follow-up is 36.9 months against a 60-month peak, so monitoring is evaluated, not established, and high-grade or extensive disease never enters the conversation.^[13]

Close with the pair. 15 to 25% of diagnoses, most never progress; treatment cuts local events with no survival effect — so the answer is shared decision-making for personalised treatment, with annual mammography for a decade whatever she chooses.^[17]