A Randomized Controlled Trial of a 6-month low carbohydrate intervention on disease progression in men with recurrent prostate cancer: Carbohydrate and Prostate Study 2 (CAPS2)

Introduction: Both weight loss and low carbohydrate diets (LCD) without weight loss prolong survival in prostate cancer (PC) models. Few human trials tested weight loss or LCD on PC. Methods: We conducted a multi-site randomized 6-month trial of LCD vs control on PSA doubling time (PSADT) in PC patients with biochemical recurrence (BCR) after local treatment. Eligibility included BMI ≥24 kg/m2 and PSADT 3-36 months. LCD was instructed to eat 20 g/carbs/day; controls were instructed to avoid dietary changes. Primary outcome was PSADT. Secondary outcomes included weight, lipids, glucose metabolism, and diet. Results: Of 60 planned patients, the study stopped early after an interim analysis showed futility. 27 LCD and 18 controls completed the study. At 6-month, while both arms consumed similar protein and fats, LCD reduced carbohydrates intake (-117 vs. 8g, p