Obesity modifies prostatic specific antigen in men over 45 years

Area of Science:

• Urology
• Endocrinology
• Oncology

Background:

• Serum prostate-specific antigen (PSA) levels are a key biomarker in prostate cancer screening.
• Obesity is increasingly prevalent and may influence PSA concentrations.
• Previous studies suggest a potential inverse relationship between body mass index (BMI) and PSA levels.

Purpose of the Study:

• To investigate the underlying mechanisms for lower serum PSA concentrations observed in obese men.
• To determine if plasma hemodilution or decreased serum testosterone levels contribute to reduced PSA in obesity.
• To analyze the relationship between BMI, PSA mass, and prostate volume.

Main Methods:

• A cohort of 413 men aged 45-75 years undergoing prostate cancer screening was studied.
• Measurements included weight, height, serum testosterone, and total PSA concentration.
• Calculations involved body mass index (BMI), plasma volume, and PSA mass; prostate volume was estimated via transrectal ultrasound.

Main Results:

• A significant inverse correlation was found between BMI and serum PSA concentration (r= -0.235; P= 0.001).
• BMI positively correlated with plasma volume (r= 0.687; p= 0.001), suggesting hemodilution.
• PSA mass was lower in obese and morbidly obese individuals (P= 0.0063), while serum testosterone and prostate volume did not significantly differ across BMI groups.

Conclusions:

• Lower serum PSA concentrations in obese men are primarily attributed to plasma hemodilution.
• Obesity does not appear to significantly lower serum testosterone levels, and thus is unlikely to cause reduced PSA mass through this mechanism.
• These findings highlight the impact of body composition on PSA levels and warrant consideration in prostate cancer risk assessment.