PD30-09 RANDOMIZED CONTROLLED TRIAL OF A 6-MONTH LOW CARBOHYDRATE INTERVENTION ON WEIGHT AND DISEASE PROGRESSION IN MEN WITH RECURRENT PROSTATE CANCER: CARBOHYDRATE AND PROSTATE STUDY 2 (CAPS2)

Abstract

INTRODUCTION AND OBJECTIVES: Both weight loss and low carbohydrate (carb) diets (LCD) without weight loss (0-20% carb kcals) prolong survival in prostate cancer (PC) models. Few human trials tested weight loss on PC. No prior study tested a LCD to delay PC growth. We tested if weight loss via a LCD slowed PSA doubling time (PSADT) in overweight/obese men with biochemical recurrence (BCR) after PC treatment. METHODS: We conducted a multi-site pilot randomized controlled trial testing a 6-mo LCD intervention vs control on PSADT (NCT01763944). Men had BMI ≥24 kg/m2, received prior PC surgery or radiation, had PSA 0.4-20.0 ng/ml (3-20 if prior radiation) in the past 3 mos, and PSADT 3-36 mos. LCD men were asked to eat <20 g/carbs/day with no other limits. Controls were told to make no diet change. Arms were compared by rank-sum. Primary outcome was difference in PSADT. Secondary outcomes were weight loss, lipids, glucose metabolism markers and diet. Post-hoc analysis compared log-transformed PSADT adjusted for baseline factors via linear regression and percent with PSADT slowing. RESULTS: 58 men were randomized and 46 completed the study (27 LCD, 19 control). At baseline, arms were similar in age and diet but the LCD arm had lower PSA (1.2 vs 2.3 ng/ml) and shorter PSADT (37% vs 26% <9 mos). At 6-mo, while both arms ate similar amount of protein, total and saturated fats, LCD men had significantly lower median carb intake vs controls (37 vs. 157 g, p<0.001).There was no difference in PSADT by arm (p=0.68). LCD men significantly reduced weight, HDL, triglycerides and hbA1c with no difference in total cholesterol or glucose (table). After accounting for pre-study PSADT, baseline PSA, primary treatment and hemoconcentration which occurs with weight loss, PSADT was suggestively slower with LCD (p=0.08). PSADT slowed in 70% of LCD vs. 47% controls (p=0.14). All study-related adverse events were mild. CONCLUSIONS: Among men with BCR, despite imperfect compliance, a LCD induced dramatic weight loss and did not affect PSADT implying a LCD has no adverse effects on PC growth and can safely be used by BCR patients. In post-hoc analyses adjusting for baseline differences and hemoconcentration, a LCD suggestively slowed PSADT. Further study of a LCD to slow PC growth is warranted.