Body mass index: A potential risk factor for breast cancer in minority patients.

Abstract

1599 Background: Breast cancer (BC), the most common cancer among women in the United States, has many established risk factors including reproductive factors, hormone use, and obesity. Obesity has also been associated with a poorer prognosis. Serum estrogen levels are higher in obesity, and may influence the characteristics and development of BC. African-Americans (AA) have been found to have a poorer prognosis for undefined reasons. In previous studies linking obesity to BC prognosis, AA women have been under-represented. This study was undertaken to look at the association of body mass index (BMI), estrogen receptor (ER) status, and stage at diagnosis (dx) in minority patients (pts). Methods: A retrospective review of the tumor registry at an urban, tertiary care medical center identified 474 women with pathologically confirmed BC from 2005 to 2010. Clinical information at dx including race, age, family history, stage, height and weight, and menopausal status was obtained. The BMI (lb/in²) at dx was calculated and pts were categorized into four groups: obese (OB) (>30), over-weight (OW) (25-29.9), normal weight (NW) (18.5-24.9), and underweight (UW) (<18.5). Pathology was reviewed to confirm ER status. 60% (284/474) of pts had complete information and were evaluable. Results: Of the 284 pts, 71% were AA, 3% Asian, 5% Hispanic, 14% White Non-Hispanic, and 7% other. The age range was 28 to 96 years (mean 60 years). 80% of pts were post-menopausal. 41% had a family history of malignancy. Staging was as follows: 16%, DCIS, 22% stage I, 37% stage II, 18% stage III, and 7% stage IV. 70% were ER (+). 2% were UW. 20% were NW. 30% were OW. 48% were OB. Higher BMI pts were more likely to have ER (+) BC (p==0.044) (see table). There was statistically significant correlation between higher BMI and advanced stage in this cohort (p==0.050). Conclusions: The majority of BC pts in this cohort were AA and OW or OB. A higher BMI correlated with ER (+) status and advanced stage. The impact that obesity has on BC characteristics and prognosis is complicated as it is influenced by path-physiology, as well as psycho-social factors. Further studies including evaluation of weight control on BC in AA women is warranted. BMI No. of ER-positive pts No. of ER-negative pts OB 101 35 OW 59 25 NW 36 21 UW 2 5