Abstract P3-11-07: Multivitamin Use and Breast Cancer Prognosis and Survival in a Prospective Cohort Study: The Life After Cancer Epidemiology (LACE) Study

Abstract

Abstract Background: Compared to healthy populations, breast cancer patients are more frequent users of multivitamins (57-62% compared to 38% in NHANES 1999-2000), yet no studies to date have examined the association between multivitamin use and breast cancer outcomes. Material and Methods: Women primarily from the Kaiser Permanente Northern California (KPNC) Cancer Registry diagnosed from 1997 to 2000 with early stage primary breast cancer (Stage I ≥1 cm, II, or IIIA), were age 18 to 70 years at study enrollment, and completed breast cancer treatment entered the LACE cohort on average two years post-diagnosis. Information on multivitamin (MV) use since breast cancer diagnosis (including duration and frequency) and five years before diagnosis (ever or never use ≥3 times/wk for ≥1 year), as well as demographic and other lifestyle factors, were collected from a mailed questionnaire. Tumor and treatment characteristics were obtained from the KPNC Cancer Registry and clinical databases. Outcomes, including recurrence and all-cause mortality, were ascertained yearly by mailed questionnaire and verified by medical record review. Recurrence was defined as local/regional and distant disease, new contralateral breast cancer, and breast cancer death if no previous recurrence was recorded. All-cause death included death from any cause. Among 2,240 women, 363 recurrences, 202 breast cancer deaths, and 372 overall deaths were confirmed as of 7 May 2010. Delayed entry Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI), adjusting for age at diagnosis, positive nodes, stage, treatment, and hormone receptor status in the recurrence models, with further adjustment for smoking history, physical activity, diet, and race/ethnicity in the mortality models. Follow-up began at date of study entry and ended at date of first cancer recurrence or death, depending on the analysis, or were censored at date of last contact for women with no event. Results: 49% and 65% reported using MV with minerals (MVM) and 13% and 19% MV without minerals (MVNM), pre-and post-diagnosis, respectively. Compared to never use, ever use of MVM after diagnosis was associated with decreased risk of recurrence (HR = 0.80; 95% CI: 0.65-1.00) and breast cancer death (HR = 0.71; 95% CI: 0.53, 0.95). Continual use of MVM from pre-to post-diagnosis at least 3 times/wk compared to never use was associated with decreased risk of recurrence (HR = 0.69; 95% CI: 0.53, 0.89) and breast cancer death (HR = 0.58; 95% CI: 0.41, 0.82), and possibly limited to women who had radiation therapy. An inverse trend of increasing frequency of post-diagnosis MVM use up to 6-7 d/wk with decreasing risk of recurrence (p=0.07) and death (p=0.04) was observed; a similar trend of increasing duration up to ≥12 months with decreasing risk of breast cancer death (p=0.04), but not recurrence (p=0.17), was apparent. No associations were found for MVM and overall mortality, and MVNM and all endpoints. Conclusion: Multivitamin use appears to be beneficial in decreasing a woman's risk of breast cancer recurrence and death. Funded by NCI R01 CA129059 Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-11-07.