Prostate cancer causes
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [2]
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Overview
Etiology
The specific causes of prostate cancer remain unknown.[1] A man's risk of developing prostate cancer is related to his age, genetics, race, diet, lifestyle, medications, and other factors. The primary risk factor is age. Prostate cancer is uncommon in men less than 45, but becomes more common with advancing age. The average age at the time of diagnosis is 70.[2] However, many men never know they have prostate cancer. Autopsy studies of Chinese, German, Israeli, Jamaican, Swedish, and Ugandan men who died of other causes have found prostate cancer in thirty percent of men in their 50s, and in eighty percent of men in their 70s.[3] In the year 2005 in the United States, there were an estimated 230,000 new cases of prostate cancer and 30,000 deaths due to prostate cancer.[4]
A man's genetic background contributes to his risk of developing prostate cancer. This is suggested by an increased incidence of prostate cancer found in certain racial groups, in identical twins of men with prostate cancer, and in men with certain genes. In the United States, prostate cancer more commonly affects black men than white or Hispanic men, and is also more deadly in black men.[5] Men who have a brother or father with prostate cancer have twice the usual risk of developing prostate cancer.[6] Studies of twins in Scandinavia suggest that forty percent of prostate cancer risk can be explained by inherited factors.[7] However, no single gene is responsible for prostate cancer; many different genes have been implicated. Two genes (BRCA1 and BRCA2) that are important risk factors for ovarian cancer and breast cancer in women have also been implicated in prostate cancer.[8]
Dietary amounts of certain foods, vitamins, and minerals can contribute to prostate cancer risk. Men with higher serum levels of the short-chain ω-6 fatty acid linoleic acid have higher rates of prostate cancer. However, the same series of studies showed that men with elevated levels of long-chain ω-3 (EPA and DHA) had lowered incidence.[9] A long-term study reports that "blood levels of trans fatty acids, in particular trans fats resulting from the hydrogenation of vegetable oils, are associated with an increased prostate cancer risk."[10] Other dietary factors that may increase prostate cancer risk include low intake of vitamin E (Vitamin E is found in green, leafy vegetables), omega-3 fatty acids (found in fatty fishes like salmon), and the mineral selenium. A study in 2007 cast doubt on the effectiveness of lycopene (found in tomatoes) in reducing the risk of prostate cancer.[11] Lower blood levels of vitamin D also may increase the risk of developing prostate cancer. This may be linked to lower exposure to ultraviolet (UV) light, since UV light exposure can increase vitamin D in the body.[12]
There are also some links between prostate cancer and medications, medical procedures, and medical conditions. Daily use of anti-inflammatory medicines such as aspirin, ibuprofen, or naproxen may decrease prostate cancer risk.[13] Use of the cholesterol-lowering drugs known as the statins may also decrease prostate cancer risk.[14] More frequent ejaculation also may decrease a man's risk of prostate cancer. One study showed that men who ejaculated five times a week in their 20s had a decreased rate of prostate cancer, though others have shown no benefit.[15][16] Infection or inflammation of the prostate (prostatitis) may increase the chance for prostate cancer. In particular, infection with the sexually transmitted infections chlamydia, gonorrhea, or syphilis seems to increase risk.[17] Finally, obesity[18] and elevated blood levels of testosterone[19] may increase the risk for prostate cancer.
Research released in May 2007, found that US war veterans who had been exposed to Agent Orange had a 48% increased risk of prostate cancer recurrence following surgery.[20]
Prostate cancer risk can be decreased by modifying known risk factors for prostate cancer, such as decreasing intake of animal fat.[21]
One research study, by the Cancer Council Victoria, has shown that men who report that they regularly ("more than five times per week") masturbate have up to one third fewer occurrences of prostate cancer.[22][15] The researchers hypothesize that this could be because regular ejaculation reduces the buildup of carcinogenic deposits such as 3-methylcholanthrene, produced from the breakdown of cholesterol, which could damage the cells lining the prostate. The researchers also speculated that frequent ejaculation may cause the prostate to mature fully, making it less susceptible to carcinogens. It is also possible that there is another factor (such as hormone levels) that is a common cause of both a reduced susceptibility to prostate cancer and a tendency toward frequent masturbation.
There is also some evidence that frequent sexual intercourse is associated with reduced risk of prostate cancer, although contrarily the risks associated with STDs have been shown to increase the risk of prostate cancer.[22][15] Once the lining of the prostate is affected with cancer, the only known treatments are surgery and radiation therapy. Both may limit the ability to have erections afterward.
References
- ↑ Hsing, Ann W. (2006). "Prostate cancer epidemiology". Frontiers in Bioscience. 11: 1388–1413. doi:10.2741/1891. Unknown parameter
|month=ignored (help); Unknown parameter|coauthors=ignored (help) - ↑ Hankey, BF (1999). "Cancer surveillance series: interpreting trends in prostate cancer—part I: Evidence of the effects of screening in recent prostate cancer incidence, mortality, and survival rates". J Natl Cancer Inst. 91 (12): 1017–24. doi:10.1093/jnci/91.12.1017. PMID 10379964. Unknown parameter
|month=ignored (help); Unknown parameter|coauthors=ignored (help) - ↑ Breslow, N (1977). "Latent carcinoma of prostate at autopsy in seven areas. The International Agency for Research on Cancer, Lyons, France". Int J Cancer. 20 (5): 680–8. doi:10.1002/ijc.2910200506. PMID 924691. Unknown parameter
|month=ignored (help); Unknown parameter|coauthors=ignored (help) - ↑ Jemal A (2005). "Cancer statistics, 2005". CA Cancer J Clin. 55 (1): 10–30. PMID 15661684. Unknown parameter
|month=ignored (help); Unknown parameter|coauthors=ignored (help) Erratum in: CA Cancer J Clin. 2005 Jul-Aug;55(4):259 - ↑ Hoffman, RM (2001). "Racial and ethnic differences in advanced-stage prostate cancer: the Prostate Cancer Outcomes Study". J Natl Cancer Inst. 93 (5): 388–95. doi:10.1093/jnci/93.5.388. PMID 11238701. Unknown parameter
|month=ignored (help); Unknown parameter|coauthors=ignored (help) - ↑ Steinberg, GD (1990). "Family history and the risk of prostate cancer". Prostate. 17 (4): 337–47. doi:10.1002/pros.2990170409. PMID 2251225. Unknown parameter
|coauthors=ignored (help) - ↑ Lichtenstein, P (2000). "Environmental and heritable factors in the causation of cancer—analyses of cohorts of twins from Sweden, Denmark, and Finland". N Engl J Med. 343 (2): 78–85. doi:10.1056/NEJM200007133430201. PMID 10891514. Unknown parameter
|month=ignored (help); Unknown parameter|coauthors=ignored (help) - ↑ Struewing, JP (1997). "The risk of cancer associated with specific mutations of BRCA1 and BRCA2 among Ashkenazi Jews". N Engl J Med. 336 (20): 1401–8. doi:10.1056/NEJM199705153362001. PMID 9145676. Unknown parameter
|month=ignored (help); Unknown parameter|coauthors=ignored (help) - ↑ Gann, PH and Giovannucci (2005). "Prostate Cancer and Nutrition" (PDF). Unknown parameter
|accessyear=ignored (|access-date=suggested) (help); Unknown parameter|accessmonthday=ignored (help) in .pdf format. - ↑ Chavarro et al., "A prospective study of blood trans fatty acid levels and risk of prostate cancer," Proc. Amer. Assoc. Cancer Res., Volume 47, 2006 [1]. See also Ledesma 2004 Nutrition & prostate cancer.
- ↑ Peters U, Leitzmann MF, Chatterjee N, Wang Y, Albanes D, Gelmann EP, Friesen MD, Riboli E, Hayes RB (2007). "Serum lycopene, other carotenoids, and prostate cancer risk: a nested case-control study in the prostate, lung, colorectal, and ovarian cancer screening trial". Cancer Epidemiol. Biomarkers Prev. 16 (5): 962–8. doi:10.1158/1055-9965.EPI-06-0861. PMID 17507623. Retrieved 2007-12-17.
- ↑ Schulman, CC (2001). "Nutrition and prostate cancer: evidence or suspicion?". Urology. 58 (3): 318–34. doi:10.1016/S0090-4295(01)01262-6. PMID 11549473. Unknown parameter
|month=ignored (help); Unknown parameter|coauthors=ignored (help) - ↑ Jacobs, EJ (2005). "A large cohort study of aspirin and other nonsteroidal anti-inflammatory drugs and prostate cancer incidence". J Natl Cancer Inst. 97 (13): 975–80. PMID 15998950. Unknown parameter
|month=ignored (help); Unknown parameter|coauthors=ignored (help) - ↑ Shannon, J (2005). "Statins and prostate cancer risk: a case-control study". Am J Epidemiol. 162 (4): 318–25. doi:10.1093/aje/kwi203. PMID 16014776. Unknown parameter
|month=ignored (help); Unknown parameter|coauthors=ignored (help) Epub 2005 July 13 - ↑ 15.0 15.1 15.2 Giles GG, Severi G, English DR, McCredie MR, Borland R, Boyle P, Hopper JL (2003). "Sexual factors and prostate cancer". BJU Int. 92 (3): 211–6. doi:10.1046/j.1464-410X.2003.04319.x. PMID 12887469. Unknown parameter
|month=ignored (help) - ↑ Leitzmann, Michael F. (2004). "Ejaculation Frequency and Subsequent Risk of Prostate Cancer". JAMA. 291 (13): 1578–86. doi:10.1001/jama.291.13.1578. PMID 15069045. 2004;291:1578-1586. Text "Elizabeth A. Platz, ScD; Meir J. Stampfer, MD; Walter C. Willett, MD; Edward Giovannucci, MD" ignored (help); Unknown parameter
|month=ignored (help)PMID: 15069045 - ↑ Dennis, LK (2002). "Epidemiologic association between prostatitis and prostate cancer". Urology. 60 (1): 78–83. doi:10.1016/S0090-4295(02)01637-0. PMID 12100928. Unknown parameter
|month=ignored (help); Unknown parameter|coauthors=ignored (help) - ↑ Calle, EE (2003). "Overweight, obesity, and mortality from cancer in a prospectively studied cohort of U.S. adults". N Engl J Med. 348 (17): 1625–38. doi:10.1056/NEJMoa021423. PMID 12711737. Unknown parameter
|month=ignored (help); Unknown parameter|coauthors=ignored (help) - ↑ Gann, PH (1996). "Prospective study of sex hormone levels and risk of prostate cancer". J Natl Cancer Inst. 88 (16): 1118–26. doi:10.1093/jnci/88.16.1118. PMID 8757191. Unknown parameter
|month=ignored (help); Unknown parameter|coauthors=ignored (help) - ↑ "Veterans exposed to Agent Orange have higher rates of prostate cancer recurrence". Medical College of Georgia News. May 20, 2007.
- ↑ "Position of the American Dietetic Association and Dietitians of Canada: Vegetarian diets". J Am Diet Assoc. 103 (6): 748–65. 2003. doi:10.1053/jada.2003.50142. PMID 12778049.
- ↑ 22.0 22.1 "Masturbation 'cuts cancer risk'". Health. BBC NEWS. 2003-07-16. Retrieved 2008-04-24.