The After
Breast Cancer Pooling Project was established to examine the role of physical activity, adiposity, dietary factors, supplement use, and quality of life (QOL) in
breast cancer prognosis. This paper presents pooled and harmonized data on post-diagnosis lifestyle factors, clinical prognostic factors, and
breast cancer outcomes from four prospective cohorts of
breast cancer survivors (three US-based and one from Shanghai, China) for 18,314 invasive
breast cancer cases diagnosed between 1976 and 2006. Most participants were diagnosed with stage I-II
breast cancer (84.7%). About 60% of
breast tumors were
estrogen receptor (ER)+/
progesterone receptor (PR)+; 21% were ER-/PR-. Among 8,118 participants with information on HER-2
tumor status, 74.8% were HER-2- and 18.5% were HER-2+. At 1-2 years post-diagnosis (on average), 17.9% of participants were obese (BMI ≥ 30 kg/m2), 32.6% were
overweight (BMI 25-29 kg/m2), and 59.9% met the 2008 Physical Activity Guidelines for Americans (≥ 2.5 h per week of moderate activity). During follow-up (mean = 8.4 years), 3,736 deaths (2,614 from
breast cancer) and 3,564 recurrences have been documented. After accounting for differences in year of diagnosis and timing of post-diagnosis enrollment, five-year overall survival estimates were similar across cohorts. This pooling project of 18,000
breast cancer survivors enables the evaluation of associations of post-diagnosis lifestyle factors, QOL, and
breast cancer outcomes with an adequate sample size for investigation of heterogeneity by
hormone receptor status and other clinical predictors. The project sets the stage for international collaborations for the investigation of modifiable predictors for
breast cancer outcomes.