This study aims to investigate diet, lifestyles, serum metabolomics in relation to breast cancer risk in a nested case-control study including 1,547 postmenopausal women from the Cancer Prevention Study II (CPS-II) Nutrition Cohort. The CPS-II Nutrition Cohort is a prospective cohort study of cancer incidence and mortality among 184,185 men and women, established by the American Cancer Society in 1992. Participants completed a self-administered baseline questionnaire in 1992/1993 including demographic, medical, and lifestyle information. Follow-up questionnaires were sent to living participants in 1997 and every other year to update exposure information and ascertain newly diagnosed cancers. From June 1998 through May 2001, blood specimens were collected from 21,963 women. All participants completed a short questionnaire and provided informed consent at the time of blood draw. Non-fasting whole blood collected from each participant was shipped chilled overnight to a central repository, processed, and frozen in liquid nitrogen at approximately -130 °C for long-term storage.

Of the 21,963 women who provided a blood sample, investigators identified 782 postmenopausal women diagnosed with invasive breast cancer between blood draw date and June 2011 who had not been diagnosed with cancer (other than nonmelanoma skin cancer) before blood draw or prior to their breast cancer diagnosis. Controls were 1:1 matched to cases on date of birth, date of blood draw, and race and were cancer free at the date of case diagnosis. Seventeen women who were selected as controls were later diagnosed with breast cancer, at which time they became a case. A total of 1,547 postmenopausal women were included in the breast cancer nested case-control study.

Inclusion Criteria:

• blood sample
• cancer free at blood draw

Exclusion Criteria:

• unverified breast cancer
• non-invasive breast cancer