Prostate Cancer

Rundqvist, H et al also found that serum samples after exercise inhibited growth of tumor cells (29).

Assessment and Plan: Prostate Cancer

• Screening for prostate cancer:
  • Digital rectal exam (DRE) by the primary care physician may detect abnormal nodularity of the prostate gland
  • Prostate-specific antigen (PSA) testing likely reduces mortality rate, but may result in treating some patients unnecessarily (2).
  • Recommendations for screening based on age (2):
    • Men over age 60: Evidence for benefit is not strong for PSA of less than 1 or 2 ng/ml.
    • Men age 45-60: For PSA of 1 ng/ml or greater: Retest PSA in 2-4-years, and for PSA under 1 ng/ml: Retest PSA every 6-8 years.
    • Men under age 50: For PSA 1.5 ng/ml or higher should receive frequent monitoring.

• PSA testing is often used for guidance of prostate cancer therapy following diagnosis (3).

• Known risks of prostate cancer: Age over 65 years, family history, African American (4), obesity (5), smoking (5), sedentary lifestyle (5), and alcohol use (6).

• The Prostate Cancer Prevention Trial on finasteride found that (33):
  • 10.5% of subjects developed prostate cancer vs. 14.9% in the placebo group.
  • High grade prostate cancer was seen in 3.5% of the finasteride group, and in 3% of the placebo group.
  • Long term survival was similar in both low and high grade prostate cancers compared to their respective placebo groups.
  • Treatment with finasteride resulted in reduction of prostate cancer risk by 30%.

• Prostate cancer prevention with supplements:

• Selenium and prostate cancer:
  • Preventive Health Advisor recommends selenium intake from food sources at the recommended daily allowance of 55 mcg per day for adult men. Selenium supplements are not recommended and may result in toxicity in doses over 400 mcg per day. Please see the selenium section in Preventive Health Advisor to research benefits of selenium intake and foods high in selenium.
  • Toenail selenium level was found to be significantly higher in control subjects without prostate cancer than in subjects with prostate cancer (7). Higher toenail selenium was associated with a reduced risk of advanced prostate cancer with an odds ratio (OR) for prostate cancer of 0.4 comparing the highest with the lowest quintile of toenail selenium content (7).
  • The Nutritional Prevention of Cancer Study Group found that 200 mcg of selenium taken by subjects with the lowest two thirds of serum selenium levels or with a PSA of less than or equal to 4.0 ng/ml at the start of the trial, had a 49% lower incidence of prostate cancer (8,9). The patients with higher baseline selenium levels at the start of the trial did not benefit from selenium (8,9).
  • The SELECT trial was a randomized, placebo controlled trial with over 35,000 men greater than age 50 with no sign of prostate cancer randomized to receive selenium 200 mcg, vitamin E 400 I.U., placebo or both for 7-12 years. This trial found that vitamin E significantly increased the risk of prostate cancer compared with placebo, and determined that prostate cancer was not prevented by selenium supplementation (10,11).
  • A case cohort study by Kristal AR, et al based on data from SELECT trial found that (12):
    • Men with high toenail selenium who took a selenium supplement or selenium plus vitamin E had a 91% higher risk of aggressive prostate cancer.
    • Neither selenium supplementation alone, nor selenium supplementation plus vitamin E, reduced the risk of prostate cancer in men with a low selenium status.
    • Vitamin E increased the risk of prostate cancer in men with low selenium toenail content.
    • Authors concluded that selenium should not be consumed in higher doses than the recommended daily allowance.

• Vitamin E and prostate cancer: Vitamin E is not recommended as a supplement based on findings in the SELECT trial (10,11).

• Flaxseed supplementation and prostate cancer:
  • A pilot study in prostate cancer patients suggested that a low-fat, diet with 30 grams of ground flaxseed daily for 6 months (13):
    • Lowered PSA (8.47 to 5.72 ng/mL; P = 0.0002)
    • Lowered cholesterol (241.1 to 213.3 mg/dL; P = 0.012)
    • Had no change in total testosterone.
    • Decreased proliferation of benign prostate epithelium from 0.022 to 0.007 (P = 0.0168)

• A low fat diet plus 30 grams of ground flaxseed daily for 30 days showed a tumor proliferation index of 3.23 for controls and a reduced tumor proliferation index for the following (14):
  • Flaxseed-supplemented arm proliferation index of 1.66.
  • Low fat diet proliferation index of 2.56.
  • Flaxseed-supplemented plus low fat diet arm proliferation index of 1.5.
  • Flaxseed-supplemented arm proliferation index of 1.66

• Lycopene and prostate cancer: Lycopene research for the prevention of prostate cancer over the years has shown mixed results, but has good potential in prevention of prostate cancer and does not have significant evidence of harm for doses under 15,000 mcg daily in the trials reviewed for food and supplement sources.
  • During the Prostate Cancer Prevention Trial, no correlation was found between serum lycopene levels and the risk of prostate cancer. (15)
  • A systematic review using 8 randomized controlled trials with lycopene did not find strong enough evidence to support the use of lycopene for prevention of BPH or prostate cancer. (16)
  • The Health Professionals Follow-Up Study found the following (17):
    • Men who consumed more lycopene, lower amounts of alcohol, less fat, less coffee, but more fruit, vegetables, and fiber were found to have a 28% lower risk of all types of prostate cancer.
    • These men also had a 53% lower risk of dying from prostate cancer.
    • The highest quintile of lycopene intake (about 13,400 mcg per day) compared with the lowest quintile of lycopene intake (about 3200 mcg per day) with a negative PSA test showed biomarkers in the tumors suggestive of less angiogenesis.
    • Men who consumed a higher lycopene intake in the early phase of the study had a lower risk of prostate cancer than those with a higher lycopene intake later in the study.

• Excess calcium intake appears to increase the risk of prostate cancer: Preventive Health Advisor recommends avoiding a calcium intake of over 2000 mg daily from diet and supplements.
  • A cohort of over 65,000 men followed for 6-7 years revealed that intake of calcium over 2000 mg per day in the form of dietary and supplement intake was associated with a moderate increase in risk of prostate cancer, but risk of prostate cancer was not increased with dairy intake, or with lower levels of dietary calcium intake (31).
  • Chung et al reviewed calcium and prostate cancer risk as part of a systematic review of health outcomes, and found that a number of studies reported that high calcium intakes were associated with an increased risk of prostate cancer (32).

• Prostate cancer and ginger extract: Ginger extract has anti-inflammatory, antioxidant and anti-proliferative action, and inhibited growth of prostate cancer, but more research is needed on this agent (18).

• Prostate cancer and dietary modifications:
  • A review of 46 published research studies reported an increase in risk of advanced prostate cancer in those with a regular dietary intake of thoroughly cooked meats, saturated fat, and calcium (19).
  • Mediterranean diet and prostate cancer:
    • Ferrís-Tortajada, J et al expressed that the risk of prostate cancer is reduced on those with intake of a Mediterranean diet when compared to a Western-style diet (20).
  • Fish intake and prostate cancer:
    • A cohort study from Japan found that a higher intake of fish had a lower risk of dying from prostate cancer than those with a lower intake of fish (30).
    • A review and meta-analysis confirmed that prostate cancer mortality was lower among subjects with fish consumption, but no reduction in the incidence of prostate cancer was seen (22).
  • Fiber intake and prostate cancer:
    • Men with the highest total fiber, highest insoluble fiber, and highest legume intake had a 53%, 54%, and 45% lower risk of prostate cancer respectively when compared to the lowest intakes (23).
    • Soluble fiber, vegetable, and fruit intake did not lower or increase the risk of prostate cancer (23).

• Prostate cancer and vegetables:
  • Cohen, JH et al noted the following findings (24):
    • 28 servings of vegetables per week vs. 14 servings per week produced an odds ratio of 0.65.
    • 3 or more servings of cruciferous vegetables (broccoli, cabbage, kale, cauliflower) per week compared to under one serving per week resulted in an odds ratio of 0.59 (41% lower risk).
    • Lutein plus zeaxanthin intake of over 2000 mcg daily compared with intake of under 800 mcg daily resulted in a an odds ratio of 0.68 (32% lower risk).
    • There was no improvement in the risk of prostate cancer between the cohorts when different amounts of fruit intake were compared.

• Prostate cancer and allium vegetables: A population-based, case–control study showed (25):
  • Men with the highest intake of allium vegetables (>10 grams daily) had a 49% risk reduction of prostate cancer than those within the lowest intake category (2.2 grams daily).
  • Reductions in risk for men in the highest intake categories (compared to the lowest intake categories) for garlic was 53% (OR = 0.47) and 70% for scallion consumption (OR = 0.30).
  • These benefits were more significant in men with localized, rather than advanced prostate cancer.

• Dairy products, dietary calcium, vitamin D and prostate cancer:
  • A meta-analysis and systematic review of 45 observational studies showed that consumption of dairy products, calcium, and vitamin D showed no increase in the risk of prostate cancer (26).
  • Cohort studies demonstrated no link between dairy or milk consumption and increased risk of prostate cancer, nor did case control studies of calcium intake (26).
  • Vitamin D intake was not correlated with increased prostate cancer risk. (26)

• Prostate cancer and exercise: If a person is approved by their physician for exercise, Preventive Health Advisor recommends a vigorous exercise program to help prevent prostate cancer for at least 9 MET hours per week. This is equivalent to about 9 hours per week of running a 10-12 minute mile, aerobics, swimming, bicycling, tennis racquetball, tennis, rowing, canoeing or other vigorous exercise activity on a weekly basis. This level of activity is achievable by the beginner by slowly increasing duration, frequency, and intensity over the long term. See the Aerobic Exercise section for more information.
  • Epidemiological evidence for prostate cancer prevention: Heitkamp and Jelas concluded that exercise done for recreation or employment related purposes did not appear to reduce the risk of prostate cancer, but intense exercise has been shown to represent good evidence for prostate cancer prevention. (27)
  • Factors of race and exercise on prostate cancer risk:
    • White men who exercised 9 or more MET hours per week were 53% less likely to have a biopsy positive for prostate cancer than white men who exercised under 9 MET hours per week (odds ratio of 0.47) (4).
    • The risk of having a positive biopsy result was not reduced in black men who exercised (4).

• Effects of exercise on prostate tumor cells: Treating prostate cancer cells using serum from subjects after a low fat diet and exercise program inhibited growth of tumor cells better than serum from obese and sedentary subjects (28,29).