Purpose: To examine whether weight gain after diagnosis of breast cancer affects the risk of breast cancer recurrence.
Patient and methods: Patients included 3215 women diagnosed with early stage breast cancer (Stage I >1 cm., II, and IIIA) who were enrolled either in an observational cohort of breast cancer survivors or were part of the comparison group of a dietary intervention trial to prevent breast cancer recurrence. We computed weight change from 1 year prior to diagnosis to study enrollment. Delayed entry Cox proportional hazards models were used to evaluate associations of categories of weight change with time to recurrence, controlling for known prognostic factors.
Results: Neither moderate (5-10%) nor large (> 10%) weight gain (HR 0.8, 95% CI, 0.6-1.1; HR 0.9, 95% CI, 0.7-1.2, respectively) after breast cancer diagnosis was associated with an increased risk of breast cancer recurrence in the early years post-diagnosis (median time of 73.7 months from diagnosis).
Conclusion: Our research provides evidence that weight gain commonly seen in the first several years following a breast cancer diagnosis does not increase a woman's risk for breast cancer recurrence in the first 5-7 years post-diagnosis. However, this research does not address the effects of weight gain on overall survival or on the risk of other new cancers, other prognostic outcomes of concern to the breast cancer survivor.