Over two thousand women with stage I, II or IIIA were enrolled in a study about two years after their breast cancer diagnosis. The use of a multivitamin pre-diagnosis and post-diagnosis was assessed with a questionnaire in Kaiser Permanente patients from Northern California. A yearly self-report and verification of their medical records was evaluated. Overall, 54% of the group reported using multivitamins pre diagnosis and 72% reported use post diagnosis. There were a total of 380 recurrences of breast cancer, 212 deaths from breast cancer and 396 total deaths out of the 2,236 women. The use of multivitamins after diagnosis was not associated with any outcome when compared to women who never used multivitamins. For those women who used multivitamins persistently from pre- to post-diagnosis, there was a decreased risk or recurrence, although not statistically significant, when compared to never users. There was a protective association in women who had been treated with radiation only and both radiation and chemotherapy. In addition, women who consistently used multivitamins before and after their diagnosis ate more fruits and vegetables, were more physically active and had better overall survival. In essence, those women who have a habit of multivitamin use before and after diagnosis and have overall healthier diet and exercise habits may improve their survival outcome after a breast cancer diagnosis.
Commentary: This study, called the LACE study is one of the larger prospective studies of breast cancer survivors that have examined multivitamin use and lifestyle factors in relation to breast cancer outcomes. Unfortunately, those women who only used the multivitamins in the 2 years after their breast cancer diagnosis did not receive any protective benefit. However, for those women who used multivitamins before their diagnosis and for the two years after, there was a possible associated reduction in breast cancer related outcomes and overall death. Specifically, those women who were in the top rung of healthy lifestyle habits by eating at least 5.5 servings of fruits and vegetables per day and some kind of physical activity at least 16 hours/week plus used multivitamins before and after diagnosis, they had a 60-70% reduction in the risk of dying from breast cancer or other illnesses.
Which ingredients in the multivitamins may be more or less important in this population remains to be answered. Other studies on breast cancer outcomes have looked more specifically at the antioxidants. The largest study is the Shanghai study that reported the use of vitamin C, E and/or multivitamins during the first 6 months after their breast cancer diagnosis was associated with a decreased risk of recurrence and overall mortality. In a sub analysis of the current LACE study, frequent use of vitamin C and E was associated with reduced risks of recurrence of breast cancer and vitamin E was associated with reduced risk of overall mortality.
While the results of the current study were small for a protective effect of multivitamins before and 2 years after diagnosis of breast cancer along with healthier diet and physical activity lifestyles, the trend is an important message for our patients.
Kwan M, Greenlee H, Lee V, Castillo A, et al. Multivitamin use and breast cancer outcomes in women with early-stage breast cancer: the Life After Cancer Epidemiology study. Breast Cancer Res Treat 2011;130:195-205.