Plasma Leptin Levels and Risk of Incident Cancer: Results from the Dallas Heart Study

PURPOSE: Leptin dysregulation has been postulated to affect cancer risk through its effects on obesity and inflammation. Epidemiological data evaluating this relationship are conflicting and studies in non-white cohorts is lacking. Therefore, we examined the association of leptin with the risk of incident cancer in the multiethnic Dallas Heart Study (DHS). METHODS: Participants enrolled in the DHS without prevalent cancer and with baseline leptin measurements were included. Incident cancer cases were identified through a systematic linkage of the DHS and the Texas Cancer Registry. Leptin was evaluated both as a continuous variable and in sex-specific quartiles. Multivariable Cox proportional hazards modeling was performed to examine the association between leptin levels with incident cancer after adjusting for age, sex, race, smoking status, alcohol use, family history of malignancy, body mass index (BMI), diabetes mellitus and C-reactive protein. RESULTS: Among 2,919 participants (median age 44 years; 54% women; 70% nonwhite; median BMI 29.4 kg/m(2)), 190 (6.5%) developed cancer after median follow- up of 12 years. Median leptin levels were 12.9 (interquartile range [IQR] 5.8–29.5) ng/ml in the incident cancer group vs. 12.3 (IQR 5.4–26.4) ng/ml those without an incident cancer (p = 0.34). Leptin was not associated with cancer incidence in multivariable analysis (unit standard deviation increase in log-transformed leptin, hazard ratio 0.95; 95% confidence interval, 0.77–1.16; p = 0.60). No association was observed in analyses stratified by sex, race/ethnicity, diabetes, or obesity status. CONCLUSIONS: In this study of a predominantly minority population, no association between premorbid leptin levels and cancer incidence was demonstrated. Despite preclinical rationale and positive findings in other studies, this association may not replicate across all racial/ethnic populations.