A high omega-3, low omega-6 diet with fish oil for men with prostate cancer on active surveillance: The CAPFISH-3 randomized clinical trial.

312 Background: Men on active surveillance for prostate cancer are extremely interested in dietary changes or supplements to prevent progression of their disease. There are presently no prospective trials supporting such changes. We sought to determine if a high omega-3, low omega-6 fatty acid diet with fish oil capsules (D+FO) decreases proliferation (Ki-67) in prostate biopsies in men with prostate cancer on active surveillance over a 1-year time period. Methods: In this Phase II, prospective randomized trial, men (N=100) with grade group 1 or 2 prostate cancer that elected active surveillance were randomized to the D+FO or a control group. Same site prostate biopsies were obtained at baseline and 1-year tracked using an image-fusion device. The primary endpoint was the change in Ki-67 index from baseline to 1-year from same site biopsies compared between the groups. Ki-67 index was determined using multiplex immunofluorescence analysis. Secondary outcomes included compliance, grade group, maximum tumor length, the Decipher 22 gene score, serum PSA, lipid levels, and adverse events. Results: The Ki-67 index decreased in the D+FO group by approximately 15% from baseline to 1-year (1.34% at baseline, 1.14% at 1-year) and increased in the control group by approximately 24% from baseline to 1-year (1.23% at baseline, 1.52% at 1-year) resulting in a statistically significant difference in the change of Ki-67 index between the groups (95% CI 2%, 52%, p=0.043). There was no significant difference in the secondary outcomes grade group, tumor length, decipher genomic score or PSA between the two groups. There was a significant decrease in serum triglyceride (p=0.016) and serum colony stimulating factor-1 (p=0.017) in the D+FO group compared to control. Four patients in the D+FO group were withdrawn from the trial due to adverse events related to the FO. Conclusions: A high omega-3, low omega-6 diet with FO for 1-year resulted in a significant reduction in Ki-67 index (compared to the control group), a biomarker for prostate cancer progression, metastasis and death. These findings support future Phase III trials incorporating this intervention in men on active surveillance. Clinical trial information: NCT02176902 .