Should Prostate Specific Antigen be Adjusted for Body Mass Index? Data From the Baltimore Longitudinal Study of Aging

Abstract

Purpose Obesity may be associated with lower prostate-specific antigen (PSA) through hemodilution. We examined the relationship between body mass index (BMI) and PSA by age in men without prostate cancer from a longitudinal aging study to determine whether PSA needs to be adjusted for BMI. Materials and Methods The study population included 994 men (4937 observations) without prostate cancer in the Baltimore Longitudinal Study of Aging. Mixed effects models were used to examine the relationship between PSA and BMI (kg/m2) by age. Separate models were explored in men with prostate cancer censored at diagnosis, for percent body fat measurements, for weight changes with time, and adjusting for initial prostate size in 483 men (2523 observations) with pelvic MRI measurements. Results In men without prostate cancer, BMI was not significantly associated with PSA after adjusting for age (p=0.06). A 10 point BMI increase was associated with a PSA difference of −0.03 ng/ml (95% CI, −0.40–0.49). Results were similar when men with prostate cancer were included, when percent body fat was substituted for BMI, and after adjusting for prostate volume. Longitudinal weight changes also had no significant association with PSA. Conclusions Consistent with prior studies, we found an inverse relationship between obesity and serum PSA levels. However, the magnitude of the difference was small. Thus, adjusting PSA for BMI does not appear warranted.

Impact of Body Mass Index on Outcomes After Conformal Radiotherapy in Patients With Prostate Cancer

“…Besides inherent differences in biology, diagnostic issues such as clinical understaging might be an important concern in obese prostate cancer patients. Consistent with prior studies, Loeb et al found an inverse relationship between obesity and serum prostate specific antigen (PSA) (2). Other authors found associations between diabetes and lower PSA levels (3).…”

Investigating the prostate specific antigen, body mass index and age relationship: is an age–BMI-adjusted PSA model clinically useful?

“…The explanation for the inverse relationship between BMI and PSA levels is more uncertain; one suggestion is that obesity causes hemodilution due to an increased plasma volume [22, 27, 28]; another is that reduced androgen levels and increased estrogen in overweight men cause lower circulating PSA levels [23]. The reduction in PSA caused by an increased BMI may lead to men not receiving a biopsy when a smaller man would, which may help explain the observed paradoxical inverse relationship of BMI with prostate cancer detection, but the positive relationship between BMI and increased prostate cancer mortality [24].…”

Opium Consumption Is Negatively Associated With Serum Prostate-Specific Antigen (PSA), Free PSA, and Percentage of Free PSA Levels

“…Han et al (2008) demonstrated that high blood pressure is associated with higher serum PSA levels. There is an inverse relationship between serum PSA levels and obesity (Loeb et al, 2009).…”

“…Prostate volume was determined by transrectal ultrasonography (TRUS). Because body surface area and plasma volume affect significantly serum PSA levels (Loeb et al, 2009), we calculated body surface area and plasma volume, using the following formulas for using in the future statistical analysis:…”