Diet Plus Fish Oil May Reduce Ki-67 Biomarkers in Prostate Cancer

Men with prostate cancer on active surveillance who consumed a diet high in omega-3 fatty acids and low in omega-6 fatty acids, along with fish oil supplements, experienced a significant decrease in the Ki-67 index.

Among patients with prostate cancer on active surveillance, a one-year, high omega-3, low omega-6 fatty acid diet with fish oil capsules (D + FO) demonstrated a significant reduction in Ki-67 index, a biomarker for prostate cancer progression, metastasis and death, according to study findings published in the Journal of Clinical Oncology.

From baseline to one year the Ki-67 index in the D + FO group decreased by approximately 15%. At baseline, the index was 1.34%, and after one year, it dropped to 1.14%. In contrast, the Ki-67 index in the control group increased by approximately 24% from baseline to one year. At baseline, the index was 1.23%, and after one year, it rose to 1.52%.

This resulted in a statistically significant difference in the change of Ki-67 index between the groups; however, there was no significant difference in secondary outcomes between the two groups which included grade group, tumor length, Decipher genomic score or prostate-specific antigen.

“The Ki-67 index values from our trial will potentially provide useful data for planning future prospective trials evaluating diet and lifestyle intervention trials in men on [active surveillance],” wrote study authors.

Regarding safety, four of the 50 patients randomly assigned to the D + FO group were withdrawn by the principal investigator due to side effects linked to the fish oils. One patient experienced grade 2 (moderate) flatulence, constipation and bloating. Another patient was withdrawn for grade 2 diarrhea, gastrointestinal discomfort and eructation. The last two patients were withdrawn due to grade 1 (mild) side effects — loose stools in one patient and loose stools, eructation and nausea in the other.

In this CAPFISH-3, single-center, phase 2, randomized, open-label, two-arm study, a total of 100 patients were enrolled and randomized. Patients were randomly assigned to either the D + FO group or control group.

“There are no previous trials in the literature evaluating serial Ki-67 index values over time in men on [active surveillance] and there are no reports on Ki-67 index values in patients with grade group 1 and 2 prostate cancer,” study authors wrote.

Patients in the intervention group received FO capsules, provided by Pharmavite LLC, containing a daily dose of 2.2 grams of omega-3 fatty acids, comprising of docosahexaenoic acid and eicosapentaenoic acid.

Additionally, patients in the intervention group also received monthly individualized counseling sessions in-person, via telehealth or by telephone from the study-registered dietician nutritionist. Counseling included reducing fat intake to less than 30% and decreasing consumption of foods high in omega-6 fatty acids such as fried foods, highly processed foods, chips and baked goods. In addition, patients were encouraged to increase omega-3 rich food intake (e.g., salmon, tuna).

Exclusion criteria included the intake of finasteride or dutasteride during the previous six months, previous treatment for prostate cancer and if the patient has allergies to fish or is a vegetarian.

“On the basis of the underlying antiprostate cancer mechanisms of a high omega-3, low omega-6 diet with FO supplements, future trials are warranted evaluating this intervention in varying stages of prostate cancer,” study authors concluded.

Reference:

“High Omega-3, Low Omega-6 Diet With Fish Oil for Men With Prostate Cancer on Active Surveillance: The CAPFISH-3 Randomized Clinical Trial,” By Dr. William J. Aronson, et al. Journal of Clinical Oncology.

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