Abstract
BACKGROUND: Although there are a large number of epidemiological studies investigating the etiological role of lifestyle factors in breast cancer, there are few studies on the association between lifestyle factors and breast cancer prognosis. To investigate the influence of lifestyle factors such as diet and physical activity, use of complementary and alternative medicine, and psychosocial factors on prognosis, we designed a large-scale cohort study of female breast cancer patients in Japan. METHODS: The planned sample size is 7200. The cohort is being conducted in collaboration with several clinical trials, a cancer registry, and daily practice. Information on clinical factors, treatment, and follow-up will be obtained from the clinical trials and participating hospitals. A self-administered questionnaire is given to subjects before, immediately after, or 1 to 5 years after surgery. Blood and tissue samples are also collected. The primary endpoint is disease-free survival. The secondary endpoints are overall survival and health-related quality of life. The follow-up period will be at least 5 years after the last participant is enrolled. Recruitment began in November 2007. CURRENT STATUS: As of April 2017, there are 5852 patients enrolled in the study along with 1430 biological samples and the study is still ongoing. The number of subjects enrolled in the study is already the largest in the world. CONCLUSIONS: The ROK study will provide much important evidence for breast cancer survivorship.