Abstract # 2040 Long-Term Results of Conservative Surgery and Radiotherapy for Ductal Carcinoma In Situ Using Lung Density Correction

Presenter: Ben-David, Merav

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The median total follow-up time was 6.6 years (range 1.3-18.2). Median age at diagnosis was 54 years (range 3083); 83% of lesions were diagnosed by mammogram only; 7% with physical exam only; 3% with both and 8% had method of detection unknown. Tumor size was less then 1cm in 60% of cases. Of the specimens assessed for grade and histologic subtype, 46% were low-intermediate grade and 62% were of comedo histology. Re-excision was performed in 66% of patients. Final margins were negative in 89% and close (<2 mm)/positive in 11%. The median whole breast dose was 50Gy (range 44.1-50Gy) and median boost dose was 10Gy (range 9.8-22Gy). The 5- and 10- year rates of local control were 94.2% and 92.6%, respectively (95% CI 91-98 % and 87-95%). 94% percent of recurrences (15/16 cases) were in the same quadrant as the original primary; 69% (11/16) were DCIS, 25% (4/16) were invasive, and 1 histology was not specified. Upon univariate analyses, positive family history of breast cancer (BC) (p=0.03) and positive final margin status (p<0.0001) were significantly associated with local recurrence (LR). Age (<50 years at diagnosis) was marginally associated with LR (p=0.06). Weight, race, menopausal status, size of primary tumor, presence of comedo necrosis, method of detection, total volume of resection and adjuvant tamoxifen were not associated with LR. In multivariate analyses, age <50 years (p=0.02) and positive surgical margins (p<0.0001) predicted LR. Four patients (2%) died from metastatic BC; the breast cancer-specific survivals at 5- and 10- years were 100% and 96%. Corresponding overall survivals were 98% and 83%, respectively. 9 patients (4.5%) were diagnosed with contralateral BC. Cosmesis was assessed by physicians in 155 patients. At the last cosmetic report, 95% of women had a good/excellent score with a mean follow up of 4.9 years. Better cosmetic results were associated with smaller total volume of excision (continuous covariate) (p=0.001), weight <200 lbs. (p=0.005), treatment energy of 6MV (p=0.006), and boost energy of <9MeV (p=0.008). In a multivariate analysis, weight and total excision volume were significantly associated with cosmetic outcome (p=0.004 and 0.001, respectively).

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