Abstract P4-10-04: Rates of Second Malignancies after Definitive Local Treatment for Ductal Carcinoma In Situ of the Breast

Abstract

Abstract Background: We analyzed the risk of developing second malignancies in patients with ductal carcinoma in situ (DCIS) undergoing surgery and radiotherapy (S+RT) versus surgery alone (S). Material and Methods: The S+RT cohort consisted of 256 women treated with breast conserving therapy at William Beaumont Hospital. The S cohort consisted of 2,788 women with DCIS in the regional SEER database treated during the same time period. A matched-pair analysis was performed in which each S+RT patient was randomly matched with 8 S patients (total of 2048 patients). Matching criteria included age +/− 2 years. The rates of second malignancies were analyzed overall and as contralateral breast versus non-breast cancers and by organ system. Results: Median follow-up was 13.7 years for the S+RT cohort and 13.3 years for the S cohort. The overall 10-/15-year rate of second malignancies among the S+RT and S cohorts were 14.2%/24.2% and 16.4%/22.6%, respectively (p=0.668). The 15-year second contralateral breast cancer rate was 14.2% in the S+RT cohort and 10.3% in the S cohort (p=0.439). The 15- year risk of a second non-breast malignancy was 14.2% for the S+RT cohort and 13.4% for the S alone cohort (p=0.660). When analyzed by organ system, the 10- and 15-year rates of second malignancies did not differ between the S+RT and the S cohorts for pulmonary, gastrointestinal, central nervous system, gynecological, genitourinary, lymphoid, sarcomatoid, head and neck, or unknown primary tumors. Discussion: Compared with S alone, S +RT was not associated with an overall increased risk of second malignancies in women with DCIS. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P4-10-04.