Low-Fat Fish Oil Diet for Prostate Cancer Prevention

Jonsson Comprehensive Cancer Center

Status: Completed

Conditions: Prostate Cancer

Treatments: Procedure: Radical Prostatectomy; Dietary Supplement: Fish Oil; Other: Medical Examination; Dietary Supplement: Western Diet; Dietary Supplement: Low-Fat Diet; Other: Blood Draw; Dietary Supplement: Vitamin E supplement; Other: Dietary Interview

Study type: Interventional

Funder types: Other; NIH

Identifiers

NCT00798876

01-07-026

11-002610 (Other Identifier)

P50CA092131-01A1 (U.S. NIH Grant/Contract)

Details and patient eligibility

About

Studies on patterns of how many men get prostate cancer in other countries show that environment contributes to the high incidence of prostate cancer in the United States. Epidemiology studies suggest that this influence may be reduced by the diet of men at risk of getting prostate cancer. Although the exact nature of the effects of diet are not completely known, the amount of fat eaten appears to affect the number of men who get prostate cancer. The type of fat also seems to matter. Eating more of a type of fat called omega-3 polyunsaturated fat is associated with decreased prostate cancer risk. Omega-3 fat comes from fish and is quite different from the type of fat from animals and vegetables (omega-6 fat). Because the exact mechanism of this reduction in prostate cancer risk is not known, no blood test indications, called markers, have been discovered that would show the effect working.

Study doctors designed this study to try to find markers in the blood tests of men who have prostate cancer, and to find out if a diet supplemented with omega-3 type fat from fish oil helps reduce those markers, hence indicating that it helps reduce the cancer in these men. These men will be compared to men with prostate cancer whose diets do not contain the fish-oil fat.

The men chosen will have prostate cancer and be scheduled for operations to have their prostate glands removed. They will be chosen randomly to be given the fish-oil diet or a regular Western diet for comparison for 4 to 8 weeks. Their blood will be checked at the beginning of the diet. After the 4-to-8-week period, they will have their operations. Their blood will be checked again and a sample of their removed prostate will be examined to tell if the diet had any effect on the cancer and its markers.

Full description

1. To establish and validate intermediate biomarkers for prostate cancer prevention trials by conducting a dietary intervention trial of a low-fat diet with omega-3 fatty acid supplements in men undergoing radical prostatectomy. In initial trials it was feasible to intervene with diet and obtain tissue and serum for bioassay and biomarker development. This aim is to study the effect a low-fat, high omega-3 diet has on serum and tissue biomarkers from patients who have prostatectomies for prostate cancer. Ultimately, we hope to identify and validate intermediate markers of efficacy for large-scale dietary prevention trials.
2. To establish and validate insulin growth factor-1 (IGF-1) and insulin growth factor binding proteins (IGFBP) as relevant intermediate biomarkers for prostate cancer prevention trials. IGF-1 is a peptide growth factor that is important to the growth and progression of prostate cancer. To our knowledge, no prospective dietary intervention studies have evaluated the effect of a low-fat diet with omega-3 fatty acid supplements on IGF-1 and IGFBPs, and their potential to serve as relevant intermediate markers for low-fat dietary intervention trials for prostate cancer prevention.
3. To establish and validate serum and tissue fatty acids as relevant intermediate biomarkers for prostate cancer prevention trials. We will evaluate if men randomized to a low-fat, fish-oil-supplemented diet have increased serum ratios of omega-3:omega-6 fatty acids compared with men randomized to a control Western diet before radical prostatectomy. We also will study if patients in the low-fat, fish oil arm have increased ratios of membrane omega-3:omega-6 fatty acids as well as decreased COX-2 and decreased PGE-2 levels in benign and malignant tissue and in visceral fat. If so, it will proved further evidence to support the potential of low-fat fish oil diets for prostate cancer prevention. If serum omega-3:omega-6 ratios correlate with changes in COX-2 and PGE-2 in tissues, then serum omea-3:omega-6 ratios may be useful for monitoring activity and efficacy of low-fat fish-oil-supplemented diets in future trials.

Enrollment: 56 patients

Sex: Male

Ages: 40 to 75 years old

Volunteers: No Healthy Volunteers

Inclusion and exclusion criteria

Eligibility Criteria:

• Patient consents to participate.
• Medically able to receive and comply with the diet.
• Lives near enough for counseling and follow-up.
• Has elected to have operation to remove prostate.
• Agrees to stop diet or vitamin supplements or herbal supplements for 1 week before the study begins.
• Patient able to stop taking aspirin, COX-2 inhibitors, and other anti-inflammatory medications for 1 week before study start.
• Patient able to safely stop taking fish oil capsules 2 weeks before the diet starts.

Trial design

Primary purpose: Diagnostic

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: None (Open label)

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56 participants in 2 patient groups, including a placebo group

Standard Western Diet

Placebo Comparator group

Description:

Subjects will be asked to consume a standard Western Diet for 4 weeks. For the 4-week period, subjects will be provided with all food and beverages. Subjects will also undergo a medical examination, dietary interview, blood draw, and radical prostatectomy(as part of standard of care).

Treatment:

Other: Blood Draw

Procedure: Radical Prostatectomy

Other: Medical Examination

Dietary Supplement: Western Diet

Other: Dietary Interview

Low-Fat Diet

Experimental group

Description:

Subjects will be asked to consume a low fat diet with fish oil and vitamin E supplements for 4 weeks. For the 4-week period, subjects will be provided with all food and beverages. Subjects will also undergo a medical examination, dietary interview, blood draw, and radical prostatectomy(as part of standard of care).

Treatment:

Other: Blood Draw

Dietary Supplement: Low-Fat Diet

Procedure: Radical Prostatectomy

Dietary Supplement: Vitamin E supplement

Dietary Supplement: Fish Oil

Other: Medical Examination

Other: Dietary Interview