Racial variation of leptin levels in women with breast cancer.

Abstract

1590 Background: Incidence of breast cancer is lower in African-American women than White women, but African-American women have worse survival and represent a greater proportion of young women. Obesity is a factor in disparities. Leptin and adiponectin, hormones produced by adipose tissue, are active in breast cancer cell lines and correlate with tumor characteristics. Leptin has mitogenic effects in vitro and increases with obesity; adiponectin has inhibitory effects and decreases with obesity. Studies suggest that adipocytokine levels differ by race, adjusted for body mass index (BMI). In a small study of adipocytokine levels by race in women with breast cancer, we found that African-American women had higher levels of adipocytokines, adjusted for BMI. There was also a correlation between tumor grade and adipocytokine levels. In this study, we examined a larger number of women to replicate these findings. We measured adipocytokine levels in African-American and White women with breast cancer and correlated tumor characteristics with adipocytokine levels. Methods: We performed a retrospective case-case study of 164 African-American and 172 White breast cancer patients. Adiponectin and leptin levels were measured in serum by ELISA. Records were abstracted for BMI, age, stage, grade, ER/PR, and Her-2 neu status. Adipocytokine levels were compared between races by Chi-square analysis and adjusted for BMI. Results: Mean leptin levels were higher in African-American women, adjusted for BMI (p<0.001). There was a trend toward triple negative tumors with higher leptin levels (p==0.06). There was a correlation between younger age and premenopausal status with lower adiponectin levels, adjusted for BMI. Women aged 60 had higher adiponectin levels than women aged 40-49, (p==0.002). Premenopausal women had lower adiponectin levels (p==0.01). Conclusions: Our findings suggest that leptin levels may differ by race in women with breast cancer, adjusted for BMI. Higher levels of leptin may correlate with triple negative tumors. We found that younger women have lower levels of adiponectin, which may play a role in breast cancer in young women. With further study, differences in leptin may prove to be a biologic cause of some of the observed disparities in breast cancer.