Obesity, insulin resistance and lifestyle factors: implications for prostate cancer screening

B88

Background: Previous evidence from human studies suggests that obesity may be inversely associated with PSA among obese men. However, there is little evidence whether lifestyle and physiologic factors related to obesity, including energy intake, physical activity, insulin resistance and metabolic syndrome influence PSA levels.
 >Methods: We analyzed data for 2,458 men aged 40+ years from the 2001-2004 National Health and Nutrition Examination Survey (NHANES). PSA levels were estimated from serum using an immunoenzymatic technique. Height and weight were measured during a physical examination and body mass index (BMI; kilograms/(height in meters)) was estimated using these data.Insulin levels were measured in a subgroup of participants from stored sera. Men with the presence of 3 of the following 5 criteria were considered as having metabolic syndrome: 1.) Waist circumference >102 cm 2.) Hypertension >130/85 3.) Fasting glucose >100 md/dl 4.) Hypertriglyceridemia >150 mg/dl 5.) HDL cholesterol: <40 mg/dl. Leisure time physical activity levels were self-reported. Energy intake was estimated from a 24-hour dietary recall. We computed age-adjusted geometric mean PSA (ng/ml) among men with and without insulin resistance and metabolic syndrome (n=1200) and by level of energy intake and physical activity in the whole population. Additionally, we explored the influence of the joint exposure of obesity and each lifestyle or physiological factor.
 >Results: The geometric mean PSA (CI) among people with and without insulin resistance was 0.97 (0.9-1.1) versus 0.89 (0.8-1.0); p-value=0.49, with and without metabolic syndrome was 0.98(0.9-1.1) versus 0.89 (0.8-1.0); p-value=0.14, higher versus a lack of leisure time physical activity (0.93 (0.9-1.0) versus 0.97(0.9-1.0) and higher compared to lower energy intakes was 1.00 (0.9-1.1) and 0.92 (0.9-1.0). Further, having joint exposure to obesity and the presence of any of the lifestyle and physiological factors did not influence PSA levels.
 >Conclusions: Our data suggests that insulin resistance or metabolic syndrome, level of physical activity, or energy intake, are not related with PSA in this population. However, further studies are required to confirm these results since we had few cases with insulin resistance and metabolic syndrome.