Abstract P1-08-07: Risk factors for high-grade and low-grade DCIS in the cancer prevention study-II nutrition cohort

Abstract

Background: Nuclear grade, believed to be established early in carcinogenesis, is an indicator of ductal carcinoma in situ (DCIS) prognosis. Women with high-grade DCIS have a higher risk of local recurrence compared to women with low-grade DCIS. Risk factors for DCIS overall are well-characterized but risk factors by grade are not. Given the prognostic capabilities of grade for DCIS, it is of interest to identify whether risk factors by DCIS grade differ. Methods: Among 75,630 women enrolled in the Cancer Prevention Study-II Nutrition Cohort in 1992-1993, we identified 422 who were diagnosed with low-moderate grade DCIS (i.e. grades 1 or 2) and 355 who were diagnosed with high-grade DCIS (i.e. grade 3) during follow-up through 2013. Beginning in 1997, biennial questionnaires were administered to update exposure status, including screening mammography in the previous two years. For this analysis, these questionnaires were used to partition follow-up time into approximately two-year intervals. Because screening is strongly linked to diagnosis of DCIS, contribution of person-time within a specific interval was conditional on reporting a screening mammogram in the interval prior. Multivariate joint Cox proportional hazards regression models were used to estimate adjusted hazard ratios (HR) and 95% confidence intervals (CI) for the associations of known breast cancer risk factors with DCIS overall, and with high-grade and low-grade DCIS individually. Results: Parity (HR=0.70; 95% CI: 0.63-0.78, parous vs. nulliparous), smoking status (HR=0.69; 95% CI: 0.58-0.82, current vs. never smoking) and menopausal status (HR=0.79; 95% CI: 0.73-0.87, natural menopause Conclusions: In this study, which is the first to comprehensively assess risk factors by DCIS grade, the association between personal history of BBD and risk of DCIS appeared to differ by grade. Due to limited power for some risk factor analyses, future studies using larger prospective cohorts or pooled data should be conducted to better identify these associations. Citation Format: Puvanesarajah S, Gapstur SM, Gansler T, Patel AV, Gaudet MM. Risk factors for high-grade and low-grade DCIS in the cancer prevention study-II nutrition cohort [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-08-07.