Background: Higher body mass index (BMI) has been associated with increased distant recurrence and decreased survival for women with breast cancer. However, the relationship between BMI and locoregional recurrence (LRR) has been less well studied and was therefore the subject of this investigation.
Methods: The study identified 878 women with early-stage invasive breast cancer who underwent breast-conservation therapy (BCT) between June 1997 and October 2007. Time from diagnosis to LRR was calculated using a competing risk analysis with contralateral breast cancer (CBC), distant metastases (DM), and death as the competing risks. Gray's competing risks analysis, which included an interaction term between menopausal status and BMI, was used to identify significant risk factors for the development of LRR.
Results: After a median follow-up period of 10.8 years, LRR was diagnosed as a first event for 45 women. In a multivariable analysis, BMI was positively associated with LRR but only in premenopausal women. Specifically, when these women were compared with normal- and underweight women, both the overweight women (hazard ratio (HR), 2.97; 95 % confidence interval (CI) 1.04-8.46; p = 0.04) and the obese women (HR, 3.36; 95 % CI 1.07-10.63; p = 0.04) showed a higher risk of LRR. A similar association between BMI and disease-free survival was noted for premenopausal but not postmenopausal women.
Conclusion: For premenopausal women with invasive breast cancer who undergo BCT, BMI is an independent prognostic factor for LRR. If confirmed, these findings suggest that more aggressive treatment strategies may be warranted for these women.