A phase II prospective randomized trial aimed to determine whether a high omega-3, low omega-6 fatty acid diet supplemented with fish oil (D + FO) could reduce prostate cancer progression in men on active surveillance (AS). The primary focus was on assessing changes in the Ki-67 index, a biomarker that reflects cell proliferation, in prostate biopsies over a 1-year period.
In this trial, 100 men with grade group 1 or 2 prostate cancer who opted for AS were randomly assigned to either the D + FO group or a control group. Prostate biopsies were taken at baseline and after 1 year from the same site. The main outcome was the change in the Ki-67 index between the two time points, comparing the two groups.
The results were promising: the Ki-67 index in the D + FO group decreased by approximately 15%, from 1.34% at baseline to 1.14% at 1 year. In contrast, the control group saw a 24% increase in Ki-67 index, from 1.23% at baseline to 1.52% at 1 year. This difference in Ki-67 change between the groups was statistically significant (95% CI, 2% to 52%, P = 0.043). However, there were no significant differences in secondary outcomes, such as grade group, tumor length, Decipher genomic score, or prostate-specific antigen levels between the two groups. Additionally, four participants in the D + FO group were withdrawn due to adverse events related to the fish oil.
In conclusion, the study found that a high omega-3, low omega-6 diet with fish oil supplementation for 1 year significantly reduced the Ki-67 index in men with prostate cancer on AS. These results suggest that this dietary intervention may have potential in preventing disease progression and support the need for future phase III trials to further investigate this approach in managing prostate cancer.