Articles

Prostate Cancer

Introduction

The prostate is a walnut-sized organ that lies just below the bladder, surrounding the urethra. The function of the prostate is to enhance the motility of sperm cells by secreting a thin, alkaline fluid into the urethra.

Prostate cancer is the most common form of cancer, excluding skin cancer, in men in the United States. It is primarily diagnosed in men over 65, although it may begin much earlier. Some carcinomas of the prostate are very slow growing, while others behave aggressively. Prostate cancer often metastasizes to other tissue, including the brain, lungs, lymph nodes, and bones. Early detection is critical in order to increase the chances for survival. The cancer can be palpated upon digital rectal examination (DRE). These examinations are recommended routinely for all men over the age of 50 and high-risk men should commence at age 40.

Little is known about the causes of prostate cancer. Risk factors for prostate cancer include family history and black race. Insight into the history of the tumor is provided by histopathologic grading, surgical evaluation of the pelvic lymph nodes, and measurement of the primary lesion. A lesion with a size of less than 1.5mL in volume typically results in a good prognosis.

The majority of prostate cancers are adenocarcinomas. While most prostate cancers are found in the peripheral zone, they may occur anywhere in the prostate. Most pathologists use the Gleason grading system to assess the tumor progression. A score from 2 to 4 indicates a well-differentiated cancer; 5 to 6 correlates with a moderately differentiated cancer; and 7 to 10 indicates a poorly differentiated cancer. The poorer the differentiation of the cancer cells, the worse the prognosis. Well-differentiated tumors grow slowly, whereas poorly differentiated tumors grow rapidly and are associated with a poor prognosis.

Statistic

Cancer Research UK, 2006.

  • Worldwide, more than 670,000 men are diagnosed with prostate cancer every year, accounting for one in nine of all new cancers in males.
  • It is the second most common cancer in men after lung cancer.

Second Report of National Cancer Registry in Malaysia, 2003.

  • In 2003, there were 602 cases reported (6.4%) making prostate cancer the 6th most common cancer among males in Malaysia.
  • The age specific incidence rate rises sharply after the age of 60.
  • The overall age standardized incidence was 10.3 per 100,000 population.

National Vital Statistics Reports, Vol. 48, No. 11.

    The annual number of deaths from Prostate Cancer are 32,203 (1998).

Vital and Health Statistics Series 10, No. 200.

    Cases of Prostate Disease Reported Annually: 2.8 million (1996).

Vital and Health Statistics Series 13, No. 143.

    Number of Ambulatory Care Visits for Prostate Cancer: 2.5 million (1997).

National Cancer Institute, National Institutes of Health (NIH), Department of Health and Human Services(HHS) 1998.

    The mortality rate of Prostate Cancer(1995) is 34,475 men die of it each year.

Signs and Symptoms

[span class=alert]The following list does not insure the presence of this health condition. Please see the text and your healthcare professional for more information.[/span]

Early stages of prostate cancer are asymptomatic. Obstructive symptoms mimicking benign prostatic hyperplasia (BPH) occur later in the disease. Difficulty urinating, frequency, urinary retention, and diminished force of the urine stream are characteristic symptoms. If the cancer has spread, symptoms may include fatigue, nausea, weakness, back pain, swollen lymph nodes, discomfort in the perineum, hip pain, or weight loss. Blood may be present in the urine. Most prostatic cancers are detected in asymptomatic men who have an elevated PSA (Prostate Specific Antigen) level or a nodular or enlarged prostate at the time of examination. (1) Prostate cancer may also present clinically as a rectal mass.

General

    Initial stages are asymptomatic Difficulty urinating Urinary retention Diminished force of the urine stream Fatigue Nausea Weakness Back pain Swollen lymph nodes Discomfort in the perineum Hip pain Weight loss Hematuria

Treatment Options

Conventional

Prostate cancer screening is utilized to detect the tumor while it is localized in the prostate and is most easily and successfully treated. Biopsy of the prostate is essential for establishing the diagnosis and is indicated when an abnormality is detected by palpation or elevated PSA. Treatment of prostate cancer is determined by the stage of the disease. If the cancer is limited to the prostate, radical prostatectomy is usually performed, with or without radiation therapy. A recent study found, however, that men who had their prostates removed after diagnosis did not survive appreciably longer than those whose cancers were monitored without intervention. (2) , (3) For later stages, treatment is palliative. Because growth of the normal prostate is dependent on testicular androgens, androgen deprivation is used for treatment of advanced prostatic carcinoma. This can be achieved by four methods: surgical castration and adrenalectomy; inhibition of pituitary gonadotropin and/or ACTH production which involves estrogen therapy usually with diethylstilbestrol (DES) or treatment with luteinizing hormone-releasing hormone (LHRH) analogues such as leuprolide or buserelin; inhibition of androgen synthesis (aminoglutethimide); and inhibition of androgen binding to its receptor protein (cyproterone, flutamide, or bicalutamide). Orchiectomy may be considered, as over 90 percent of testosterone originates in the testicles. While the procedure is simple, safe, cost-effective, and produces immediate relief of symptoms, the psychological effect can be significant for many men. Chemotherapy is reserved for hormone-unresponsive disease and is used for palliation.

Nutritional Supplementation


Lycopene

Lycopene is a dietary component that seems to provide specific protection against prostate cancer. Results from the Health Professionals Follow-Up Study reported a lower prostate cancer risk among men who consumed larger quantities of tomatoes and related lycopene-containing food products. (4) In another study, significantly lower serum and tissue lycopene levels were observed in men with prostate cancer compared to controls. (5)

Tomatoes are the primary dietary source of lycopene and it has been reported that lycopene is one of the most effective quenchers of the singlet oxygen free radical. It is interesting to note that the highest concentrations of lycopene occur in the testes, adrenals, and prostate gland. (6) Lycopene concentration is highest in cooked tomato products. It is estimated that a minimum 4-6mg daily intake of lycopene is needed for prostate protection.


Selenium

The use of selenium as a protectant against prostate cancer is supported by results of a study designed to evaluate whether or not selenium supplementation could reduce the reoccurrence of either basal cell or squamous cell carcinoma. In this study, 974 men were randomized to receive either a daily supplement of 200mcg of selenium or a placebo. These men were treated for an average of 4.5 years and then followed for an additional 6.5 years.

Evaluation of secondary endpoints in men that initially had normal PSA levels revealed that selenium supplementation was responsible for a 63% reduction in the incidence of prostate cancer. Four men were diagnosed in the selenium-treated group, compared to 16 cases of prostate cancer in the placebo group. Additionally, compared to placebo controls, the individuals taking selenium also had significant reductions in colorectal cancer and lung cancer. (7)

In the Netherlands Cohort Study of 58,279 men aged 55- 69 years upon entry, over 1500 men exhibiting prostate cancer identifiers were found to have a decreased toenail selenium levels. Researchers concluded that this study confirmed the hypothesis that higher selenium levels might reduce prostate cancer risks. (8)


Vitamin E

The results of a controlled study that evaluated the incidence of prostate cancer and deaths among 29133 male smokers aged 50-69 years who took vitamin E indicated that men taking 50mg of vitamin E daily had a 32 percent lower incidence of prostate cancer, and a 41 percent reduction in deaths from prostate cancer. (9) In a similar study, among current smokers and recent quitters, men who consumed at least 100 IU of supplemental vitamin E per day had a significant reduction in the risk for metastatic or fatal prostate cancer compared with nonusers of supplemental vitamin E. (10)


Zinc

In order to insure the general health and well being of the prostate gland, zinc supplementation may be warranted. The prostate gland stores zinc and the concentration of zinc in the prostate gland is much higher than in other tissues in the human body. (11) Adequate zinc levels help to prevent enlargement of the prostate gland. This is because zinc influences the activity of the 5 alpha-reductase enzyme. When zinc levels are low, the activity of this enzyme is higher, causing a greater conversion of testosterone to dihydrotestosterone (DHT). On the other hand, when zinc levels are higher the activity of 5 alpha-reductase is reduced, and there is less conversion of testosterone to DHT. (12) Zinc not only prevents prostate enlargement; animal studies report it may also help to shrink a gland that is already swollen. (13) However, in a recent human study, consumption of over 100mg of supplemental zinc daily had a relative risk of advanced prostate cancer of 2.29 in comparison to nonusers and when taken for 10 years or more the relative risk increased to 2.37. (14)


Vitamin B6

Taking zinc alone isn’t enough to insure prostate health. Vitamin B6 influences zinc absorption. Apparently vitamin B6 helps to convert zinc to a form that is more absorbable by the tissues in the prostate. (15) Studies indicate that vitamin B6 is deficient in the diet of many Americans, a factor that may contribute to low zinc status and increased prostate problems. For example, data from the Second National Health and Nutrition Examination Survey (NHANES II) reported that 71% of males consumed less than the RDA for vitamin B6 on a daily basis. (16)

Herbal Supplementation

A study recently published in the journal European Urology, assessed dietary and environmental risks associated with prostate cancer. Through the World Health Organization, prostate cancer mortality rates were gathered for 32 countries. In addition, the researchers obtained dietary information from the Food and Agricultural Organization. After analyzing all the data, the results showed that one of the major contribution factors to prostate cancer risk was a high intake of animal products. Also found to contribute to this risk were alcohol and nonfat milk. A higher intake of onions was found to reduce the risk, followed by other vegetable products. The authors concluded that the allium (found in onions) food family was associated with a reduced risk of prostate cancer. (17)

Diet & Lifestyle

Dietary fat: There are many studies that discuss how various factors related to diet and nutrition influence cancer. Although only a small amount of this research relates directly to the prevention or treatment of prostate cancer, the following reviews have been reported.

Most studies that have evaluated the relationship between dietary fat and prostate cancer report that diets high in total fat are associated with an increased rate of prostate cancer. (18) Even though there are some inconsistencies, there is the suggestion that diets high in saturated fat and/or animal fat increase the risk of prostate cancer. (19) Most studies on dietary meat intake, seem to report an increased risk of prostate cancer with higher meat consumption. A prospective evaluation of the relationship between meat consumption and prostate cancer used the detailed dietary data from 51,529 male participants of the Health Professionals Follow-Up Study. This study concluded that intakes of red meat and dairy products appear to be related to increased risk of metastatic prostate cancer, but increased risk did not apply to all cases of prostate cancer observed, including advanced prostate cancer. (20)

Clinical Lab Assessment

Some of the following laboratory testing can provide information necessary for diagnosis and treatment. In addition, the tests listed may also give insight to functional metabolism and functional nutrient status in the body.

Hormone Assessment

Estrogen, Progesterone and Testosterone: Estradiol increases a genetic product (Bcl-2) that leads to cell proliferation and delay in apoptosis, both of which increase cancer risk. Progesterone suppresses Bcl-2 action and increases another genetic control product (p53) that slows cell proliferation and restores proper apoptosis, both of which decrease cancer risk. Testosterone (but not the DHT) stops cancer cell growth. (21) Assessment of these hormones may be useful.

Prostate Specific Antigen (PSA)

This glycoprotein, exclusive to the prostate epithelium, is a smaller, more stable molecule than PAP and does not demonstrate diurnal fluctuations. PSA is used as a marker for the detection of prostate cancer.

References

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  2. View Abstract: Matos-Ferreira A. New review of radical prostatectomy. Actas Urol Esp. Oct1997:817-21.
  3. View Abstract: Fleming C, Wasson JH, Albertsen PC, Barry MJ, Wennberg JE. A decision analysis of alternative treatment strategies for clinically localized prostate cancer. JAMA. May1993;269:2650-8.
  4. View Abstract: Clinton SK, et al. Cis-trans lycopene isomers, carotenoids, and retinol in the human prostate. Cancer Epidemiol Biomarkers Prev 1996 Oct;5(10):823-833.
  5. View Abstract: Rao AV, et al. Serum and tissue lycopene and biomarkers of oxidation in prostate cancer patients: a case-control study. Nutr Cancer. 1999;33(2):159-64.
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  7. View Abstract: Clark LC, et al. Decreased incidence of prostate cancer with selenium supplementation: results of a double-blind cancer prevention trial. Br J Urol. May1998;81(5):730-4.
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  9. View Abstract: Heinonen, OP. Prostate cancer and supplementation with alpha tocopherol and beta-carotene: Incidence and mortality in a controlled trial. J Natl Cancer Inst. Mar1998;90(6):440-446.
  10. View Abstract: Chan JM, et al. Supplemental vitamin E intake and prostate cancer risk in a large cohort of men in the United States. Cancer Epidemiol Biomarkers Prev. Oct1999;8(10):893-9.
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