Abstract P6-09-06: Effects of reproductive risk factors for ductal carcinoma in situ, invasive ductal carcinoma, and invasive ductal carcinoma with ductal carcinoma in situ on clinical outcomes
Authors: Lee J , Lee J , Oh M 
Published: May 2016

Abstract
Background: It has been well investigated with regards to reproductive risk factors of invasive ductal carcinoma (IDC), yet it is still controversial if these factors could be applicable for either ductal carcinoma in situ (DCIS) patients or invasive ductal carcinoma with ductal carcinoma (DCIS-IDC) patients. We aimed to investigate effects of reproductive risk factors on clinical outcomes of IDC, DCIS, and DCIS-IDCpatients who received proper treatments.Method: A total of 37,049 patients of IDC, and DCIS who were registered in the web-based breast cancer registration program of the Korean Breast Cancer Society (KBCS), was assessed with a retrospective design. All patients were classified into three categories: 1) patients with pure DCIS, 2) patients with IDC with DCIS(DCIS-IDC), and 3) patients with pure IDC that is less than 1 cm without lymph node metastasis; overall survival (OS) and breast cancer specific survival (BCSS) of each group in response to parity, age at first birth (AFB), breast feeding, time interval between AFB and diagnosis of breast cancer, time interval between menarche and AFB were analyzed via the multivariate Cox regression analysis was performed.Results:The high parity (≥4) considerably elevated the hazard ratio (HR) of OS in three groups (DCIS; [HR], 1.52; 95% confidence interval [CI], 0.615-3.778; P&lt;.0001,IDC; HR, 1.43; 95% CI, 0.885-2.314 ; P&lt;.0001, and DCIS-IDC; [HR], 1.44; 95% confidence interval [CI], 0.452-4.594; P&lt;.005) yet the parity influenced on the BCSS differently in the IDC group and the DCIS-IDCgroup. Meanwhile, in the DCIS-IDCgroup, the HR was elevated in which patients gave birth to 4 children whilst the HR of BCSS was lowered if they gave birth to either 1-2 children or more than 5 children. The AFB significantly reduced the HR of OS in the DCIS group and IDC group compared to nulliparous patients. In patients who breast-feed, the HRs of OS and BCSS were shown to be significantly elevated in the IDC group and DCIS group (HR of OS in IDC, 1.486;95% CI, 1.212-1.821; P=.0001 and HR of OS in DCIS, 2.036; 95% CI, 1.267-2.271 ; P=.0033; and HR of BSCC in IDC, 1.474; 95% CI, 1.111-1.957 ; P=.0072, HR of BCSS in DCIS,3.362; 95%CI, 1.18-9.56;P=0.023)(Table 3). Considering the time interval between AFB and age at diagnosis, the HR of OS was considerably elevated in all three groups (HR of DCIS, 1.067;95% CI, 1.050-1.085 ; P&lt;.0001, HR of IDC, 1.041; 95% CI, 1.034-1.049 ; P&lt;.0001, HR of DCIS-IDC, 1.031; 95% CI, 1.008-1.054 ; P=0.008) yet the HR of BCSS was only influenced in the IDC group (HR, 1.027;95% CI, 1.016-1.037 ; P&lt;.0001). When it comes to the time interval between menarche and AFB, the HR of OS was significantly elevated in the group of DCIS (HR, 1.053; 95% CI, 1.007-1.100 ; P&lt;.0219).Conclusion: The breast feeding history and age gap between AFB and diagnosis were found to be breast cancer risk factors that might be different from generally accepted trends, reducing occurrence of breast cancers. Taken altogether, we were able to demonstrate that known reproductive risk factors, such as AFB and parity, influence on clinical outcomes differently amongst the IDC group, the DCIS group, and the DCIS-IDC group.
Citation Format: Lee J, Lee J, Oh M. Effects of reproductive risk factors for ductal carcinoma in situ, invasive ductal carcinoma, and invasive ductal carcinoma with ductal carcinoma in situ on clinical outcomes. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-09-06.