Twenty-year outcomes after breast-conserving surgery and definitive radiotherapy for mammographically detected ductal carcinoma in situ

Background. Management of mammographically detected ductal carcinoma in situ (DCIS) at a single institution was reviewed to determine long-term clinical outcomes after treatment with breast-conserving therapy (BCT). Methods. Data from all patient-cases with DCIS who received BCT between 1980 and 1993 were reviewed. Patient demographics and pathologic factors were analyzed for their effect on outcomes, including ipsilateral breast tumor recurrence (IBTR) and survival. BCT included breast-conserving surgery followed by external-beam radiotherapy to the whole breast, with 86 % of patients receiving a lumpectomy cavity boost. The median dose to the whole breast was 50 Gy and 60.4 Gy to the lumpectomy cavity. Results. A total of 129 cases were evaluated; the median follow-up was 19.3 years. Twenty-one patients developed an ipsilateral breast tumor recurrence (IBTR), 76.2 % of which were invasive (n = 16). Fourteen recurrences (66 %) were within the same breast quadrant (true recurrence), while an additional 7 cases developed an IBTR elsewhere in the breast. True recurrences were more prevalent in women<45 years of age (20 %/24 % vs. 5.1 %/8 %) at 10 and 20 years (p = 0.02). The 5-, 10-, 15-, and 20-year actuarial rates of IBTR for this cohort were 8.7, 10.4, 12.1, and 16.3 % (IBTR), while overall survival at 5, 10, and 20 years was 97.6, 96.8, and 96.8 %, respectively. Conclusions. Mammographically detected DCIS remains a clinically distinct subset of noninvasive breast cancer. With 20 year follow-up, local control and overall survival are excellent after BCT.