Stage of breast cancer in relation to body mass index and bra cup size

Most studies on women with breast cancer indicate that obesity is positivel y associated with late-stage disease. Some results have shown a similar rel ationship between breast size and stage. A recent study found that the asso ciation between body mass index (BMI) and stage was limited to cancers that were self-detected, suggesting that the BMI-stage relation may be due to d elayed symptom recognition. We examined the relationships between stage and both BMI and breast (bra cup) size, stratified by method of detection, usi ng data from a population-based case-control study of 1,361 women (ages 20- 44 years) diagnosed with breast cancer during 1990-1992, Height and weight measurements and information on bra cup size, method of cancer detection an d other factors predictive of stage at diagnosis were collected during in-p erson interviews. A case-case comparison was conducted using logistic regre ssion to estimate odds of regional or distant stage rather than local stage in relation to BMI and bra size, Odds of late-stage disease were increased with higher BMI [adjusted odds ratio (OR) for highest to lowest tertile = 1.46, 95% confidence interval (CI) 1.10-1.93] and larger bra cup size (OR f or cup D vs, cup A = 1.61, 95% CI 1.04-2.48), These relationships were not modified by the method of detection. Differences in etiologic effects, rath er than differences in detection methods, may explain the relations observe d between stage and both BMI and breast size. (C) 1999 Wiley-Liss, Inc.