Pathologic Characteristics Of Second Breast Cancers (Sbc) Among Women Previously Treated For Ductal Carcinoma In Situ (Dcis) With Breast Conservation

1042 Background: While the number of women in the U.S. diagnosed with DCIS is increasing and many go on to develop SBC, pathologic characteristics of SBC and the degree of pathologic correlation with index DCIS are not well characterized. Methods: We identified women in the National Comprehensive Cancer Network (NCCN) Outcomes Database diagnosed with DCIS from 1997−2008 and treated with breast conserving surgery (BCS) who subsequently developed SBC (DCIS or invasive; ipsilateral or contralateral) at one of eight NCCN institutions. We describe the pathologic characteristics of SBC and examine the degree of correlation with the index DCIS using Fisher exact and Spearman tests. Results: Among 2,636 women receiving BCS for DCIS with a median follow-up of 55.5 months, 150 women (5.7%) experienced SBC at a median of 33.2 months after index DCIS. Of these 150 women, 105 (70.0%) had received adjuvant radiotherapy (RT) and 50 (33.3%) had received tamoxifen (Tam) for index DCIS. SBC was ipsilateral in 54.7% of cases and invasive in 50.7% of cases. For index DCIS and SBC, 60.6% and 77.5% were estrogen receptor (ER) positive, and 54.0% and 48.2% were high grade, respectively. Among all cases, grade of the index DCIS was highly correlated with grade of the SBC (p = .003), and ER status was also highly correlated between index DCIS and SBC (p = .020). There was no significant correlation for tumor size (p = .873), progesterone receptor status (p = .227), or comedo subtype (p = .074). After stratification, tumor grade remained significantly correlated among early (less than the median follow-up time) but not late SBC, and ER status was not significantly correlated among women who received RT. Tam had no significant impact on any pathologic correlations, but among women who had received Tam and developed SBC, the SBC was more likely to be a contralateral event (p = .015). Conclusions: After BCS for DCIS, SBC are likely to exhibit grade and ER status concordant with the index DCIS. This information could be complementary to estimates of overall recurrence risk for a given patient receiving BCS for DCIS, by helping predict prognostic features of a SBC and potentially influencing management of the index event.