Association of Obesity and Smoking With PSA and PSA Velocity in Men With Prostate Cancer

Abstract

Significant number of prostate tumors are slow growing and could probably be left untreated. However, many are aggressive and can spread rapidly causing patient suffering and/or death. Current technology does not allow physicians to differentiate between slow growing and aggressive tumors at diagnosis. Hence, many patients are exposed to invasive treatment and its associated morbidities such as incontinence and impotence. Markers that enable differentiation between slow and fast progressing cancer will allow physicians to prevent unnecessary treatments on men who may not need them, and focus on the men with aggressive disease. A longitudinal study was conducted ( N = 140) using mixed effects regression models to determine the association of obesity and smoking toward prostate cancer progression. These models account for correlation because of repeated measures over time, thus, using maximum amount of information provided by the subject. Estimates thus obtained are more robust and reliable than those obtained using data from a single time point. Rate of change of prostate-specific antigen (PSA) over time (PSA velocity) was used as a measure of prostate cancer progression. Results indicate that PSA velocity of overweight and obese subjects (0.59 and 1.05 ng/mL/year) was not significantly different as compared with normal weight subjects ( p values .91 and .31, respectively). For men in the highest tertile of pack-years of smoking, PSA velocity was significantly higher as compared with never smokers 1.57 ng/mL/year ( p = .04). Further studies with larger sample sizes and study designs specific to above exposures are needed before recommendations can be made to reduce weight or reduce/quit smoking.