Penile cancer

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Penile cancer is a malignant growth found on the skin or in the tissues of the penis. Squamous cell carcinoma usually originating in the glans or foreskin is by far the most common type, occurring in 9 out of 10 cases.[1] Penile cancer is extremely rare, and it tends to develop in men over the age of sixty.

Contents

Symptoms

Symptoms include redness, irritation, a sore or a lump on the penis.[2]

Pathology

  • A. Precancerous Dermatologic Lesions
  • B. Carcinoma in Situ (Bowen Disease, Erythroplasia of Queyrat)
  • C. Invasive Carcinoma of the Penis

Staging

Like many malignancies, penile cancer can spread to other parts of the body. It is usually a primary malignancy, the initial place from which a cancer spreads in the body. Much less often it is a secondary malignancy, one in which the cancer has spread to the penis from elsewhere. Doctors use the extent of metastasis to estimate what stage the disease is in, to aid in treatment decisions and prognosis. The stages are assessed as follows(Jackson's staging):

  • Stage I - Cancer has only affected the glans and/or foreskin.
  • Stage II - Cancer has spread to the shaft of the penis.
  • Stage III - Mobile (operable) inguinal lymph nodes
  • Stage IV - Fixed (inoperable) inguinal lymph nodes or distant metastasis.
  • Recurrent - Cancer that has returned after treatment.

Prognosis can range considerably for patients, depending where on the scale they have been staged. Generally speaking, the earlier the cancer is diagnosed, the better the prognosis. The overall 5-year survival rate for all stages of penile cancer is about 50%.

Treatment

There are several treatment options for penile cancer, depending on staging. They include surgery, radiation therapy, chemotherapy, and biological therapy. The most common treatment is one of five types of surgery:

  • Wide local excision - The tumor and some surrounding healthy tissue are removed
  • Microsurgery - Surgery performed with a microscope is used to remove the tumor and as little healthy tissue as possible
  • Laser surgery - laser light is used to burn or cut away cancerous cells
  • Circumcision - cancerous foreskin is removed
  • Amputation (penectomy) - a partial or total removal of the penis, and possibly the associated lymph nodes.

Radiation therapy is usually used adjuvantly with surgery to reduce the risk of recurrence. With earlier stages of penile cancer, a combination of topical chemotherapy and less invasive surgery may be used. More advanced stages of penile cancer usually require a combination of surgery, radiation and chemotherapy. In addition to all the above, treatment of the underlying disease like Brucellosis, is important to limit disease recurrence.

Risk factors

The exact cause of penile cancer is unknown.

The myth that smegma was a carcinogenic, and thus that circumcision would render a man immune to penile cancer, was invented in 1932 by a man named Abraham L. Wolbarst, who also believed that circumcision prevented epilepsy, paralysis, and masturbation.[3] No laboratory or clinical research had been done on the subject at the time, however Wolbarst's myth found its way into early medical textbooks regardless. Although the smegma hypothesis was completely disproven by an exhaustive study by Reddy in 1963,[4] circumcision advocates continue to stubbornly repeat it.

The link between the presence of human papillovirus (HPV) and genital cancer was established in the 1980s.[5][6][7][8][9][10] Poland identified human papilloma virus (HPV) types 16 and 18 as the cause of penile and cervical cancers in 1990, and that they could be spread by sexual contact.[11] At least one study suggests that circumcised men are at higher risk for HPV infection,[12] making being circumcised a risk factor.

Hellberg et al. (1986) identified tobacco use as another risk factor for cancer of the penis.[13] The use of tobacco has since been a well established risk factor in cancer of the penis.[14][15][16]

Other risks include poor hygiene, and an increased number of sexual partners (30 partners or more).[17]

Phimosis has been implicated as a risk factor in sexually active males, because a non-retractile foreskin may result in poor hygiene, and because men with phimosis are at higher risk for lichen sclerosus (also known as balanitis xerotica obliterans), which may also be a risk factor.[18] Adult males with a non-retractable foreskin who are sexually active may want to have the phimotic condition corrected. (For conservative treatment options, see phimosis.)

Circumcision as Prevention

The myth that circumcision rendered males immune to penile cancer was invented in 1932 by a man named Abraham L. Wolbarst, M.D.[19] Wolbarst wrote an article that was published in the Lancet in 1932, implicating human male smegma as carcinogenic.[20] His hypothesis had absolutely no basis in valid scientific and epidemiological research.[21] Wolbarst was directly responsible for proliferation of this myth, and all subsequent repetions of it can be traced to his opinion article, although Wolbarst himself advocated universal neonatal circumcision principally as a preventive for epilepsy, paralysis, and masturbation.[22]

Wolbarst's opinion piece led to the perpetuation of the myth that penile cancer could not happen to males that were circumcised in infancy. This myth was completely disproven when Boczko et al. reported the 9th documented case of penile cancer in a man who had been circumcised in infancy from the time of Wolbarst's opinion piece to the time of the report in 1968 (though they would maintain that "performing [circumcision] in infancy continues to be the most effective prophylactic measure against penile carcinoma").[23] Boczko et al. wrote: "The diagnosis in our patient was made late, as in the other cases reported, perhaps because the disease was presumed not to occur in those circumcised in infancy. This is clearly not so. Although rare, the diagnosis must be considered when evaluating a penile lesion even in a circumcised individual."

In 1993, Christopher Maden, Ph.D., et al. reported a study in which 110 men with penile cancer, diagnosed from January 1979, to July, 1990, were interviewed. Of these 110 men, 22 had been circumcised at birth, 19 later in life, and 69 never.[24] As cases of penile cancer in circumcised men begin to accumulate[25][26][27][28][29][30][31][32][33], it becomes clear that the assertion that circumcision eliminates the risk of penile cancer is categorically false, although some circumcision advocates continue to make this assertion.

Discussion

Advocates of circumcision may yet point to the aforementioned studies and highlight that the incidence of penile cancer was still lower in the circumcised groups of men studied, than it was in the intact group, and that thus "a lowered risk of penile cancer is observed in circumcised men." It is important to remember when looking at the studies performed in the 1950s, that the octogenarians afflicted with penile cancer were born in the 1870s, when the circumcision rate in the United States was close to zero; the majority of men in that generation who were afflicted with cancer would be intact. The increased number of cases of penile cancer found in more recent studies is reflective of the steadily increasing circumcision rates in this country (37% of Maden's cases were circumcised). Using Maden's numbers and properly adjusting his control population to match the case population for age, there was no difference in risk of developing penile cancer between men who were circumcised and those who were not. HPV (the cause of genital warts) has been found in most cases of penile cancer. Genital warts are now more common in circumcised men [34] and HPV lesions are equally common in circumcised and intact men.[35] As the number of circumcised men approaching the age at which penile cancer becomes evident (70s and 80s) it is quite likely that the vast majority of men developing penile cancer in the United States will be circumcised.

Reddy et al. examined the frequency of carcinoma of the penis from 32 hospitals in India and found a wide variation in incidence that could not be explained by the intact status of the Hindus or the circumcision practices of the Muslims. [36] Finally, circumcision does not explain why Japan and Denmark have lower penile cancer rates than the United States when circumcision, especially infant circumcision, is not common in those two countries.[37]

In "Circumcision: An American Health Fallacy," Edward Wallerstein writes: "If infant circumcision reduces penile cancer we could expect to see proportionately less penile cancer in circumcising nations as compared to noncircumcising ones. No such difference is found." Wallerstein reports that, for various years between 1966 and 1972, the annual rate of new cases of penile cancer was 0.8 for the United States (where circumcision rates are high), and 0.5 for Finland, 0.9 for Denmark and 1.1 for both Norway and Sweden (all of where circumcision rates are low). None of these differences is statistically significant.[38] Further, within the same time frame, both France and the United States had the same rate, 0.3, of deaths due to penile cancer.[39]

Incidence of Penile Cancer

In North America the rate of penile cancer has been estimated to be 1 in 100,000[40]. Maden et al reported penile cancer among a fifth of elderly patients from rural areas who had been circumcised neonatally and had been born at a time when the rate of neonatal circumcision was about 20% in rural populations.[41] Their study also shows that the rate of penile cancer among men circumcised neonatally has risen in the United States relative to the rise in the rate of neonatal circumcision.

Penile cancer is very rare in Europe and North America, occurring in about one in 100,000 men in the latter. It accounts for 0.2% of cancers and 0.1% of deaths from cancer amongst males in the United States. However, in some parts of Africa and South America it accounts for up to 10% of cancers in men.[42]


In Japan, Norway, and Sweden, the risk of penile cancer is about the same as in the US (1 in 100,000 per year).[43]

HPV Vaccine

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Infection with HPV is associated with some penile cancers. A quadri-valent vaccine (Gardasil) to prevent infection by the four most common variants of HPV has been developed, successfully tested, and approved by the US Food and Drug Administration for females between the ages of 9 and 26, and as of 2009, males between the ages of 16 and 26.[44] Gardasil has been shown to also be effective in males, and has been approved by the FDA to be marketed as such.[45]

See also


References

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  2. "Penis Cancer". http://www.medicinenet.com/penis_cancer/page2.htm. Retrieved 2008-06-24. 
  3. Wolbarst A. Circumcision and Penile Cancer. The Lancet, vol. 1 no. 5655 (January 16, 1932): pp. 150-153.
  4. D.G. Reddy; I.K. Baruah. "Carcinogenic Action of Human Smegma," Archives of Pathology, vol. 75, no. 4 (April 1963): pp. 414-420.
  5. zur Hausen H. Genital papillomavirus infections. Prog Med Virol 1985;32:15-21.
  6. Kaufman RH, Adam E: Herpes simplex virus and human papilloma virus in the development of cervical carcinoma. Clin Obstet Gynecol 1986; 3: 678-692
  7. McCance DJ, Kalache A., Ashdown K, et al. Human papillomavirus types 16 and 18 in carcinomas of the penis from Brazil. Int J Cancer 1986:37:55-59
  8. Villa LL, Lopes A. Human papillomavirus DNA sequences in penile carcinomas in Brazil. Int J Cancer 1986;37(6):853-5.
  9. McCance DJ. Human papillomaviruses and cancer. Biochem Biophys Acta 1986;823:195-206
  10. Barrasso R, De Brux J, Croissant O, et al. High prevalence of papillomavirus-associated penile intraepithelial neoplasia in sexual partners of women with cervical intraepithelial neoplasia. N Engl J Med 1987 Oct 8;317(15):916-23.
  11. Poland RL. The question of routine neonatal circumcision. N Eng J Med 1990; 322:1312-5.
  12. Cook LS, Koutsky LA, Holmes KK. Clinical presentation of genital warts among circumcised and uncircumcised heterosexual men attending an urban STD clinic. Genitourin Med 1993;69:262-4
  13. Hellberg D, Valentin J, Eklund T, Staffan Nilsson. Penile cancer: is there an epidemiological role for smoking and sexual behavior. Brit Med J 1987;295(6609):1306-8
  14. Harish K, Ravi R. The role of tobacco in penile carcinoma. Brit J Urol 1995;75(3):375-377.
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  22. Fleiss PM, Hodges F. Neonatal circumcision does not protect against cancer. BMJ 1996;312(7033):779-80.
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  28. Rogus BJ. Squamous cell carcinoma in a young circumcised man. J Urol 1987; 138: 861-2.
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  35. Aynaud O, Ionesco M; Barrasso R. Penile intraepithelial neoplasia. Specific clinical features correlate with histologic and virologic findings. Cancer 1994; 74: 1762-7.]
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  37. Kochen M, McCurdy S. Circumcision and the risk of cancer of the penis. A life-table analysis. Am J Dis Child 1980; 134: 484-6. Swafford TD. Circumcision and the risk of cancer of the penis [letter] Am J Dis Child 1985; 139: 112.
  38. Wallerstein, Edward. Circumcision: An American Health Fallacy. Springer-Verlag, New York, 1980.
  39. Hyman AB; Brownstein MH. Tyson's "Glands," Archives of Dermatology, vol. 99, no. 1 (January 1969): pp. 31-37
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  41. Maden C, Sherman KJ, Beckman AM, Hislop TG, Teh CZ, Ashley RL, et al. History of circumcision, medical conditions, and sexual activity and risk of penile cancer. JNCI 1993;85:19-24
  42. "ACS :: What Are the Key Statistics About Penile Cancer?". Archived from the original on 2007-10-30. http://web.archive.org/web/20071030194444/http://www.cancer.org/docroot/CRI/content/CRI_2_4_1X_What_are_the_key_statistics_for_penile_cancer_35.asp?sitearea=. Retrieved 2007-12-13. 
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  44. Crum C, Jones C, Kirkpatrick P (August 2006). "Quadrivalent human papillomavirus recombinant vaccine". Nature reviews. Drug discovery 5 (8): 629–30. doi:10.1038/nrd2117. PMID 16918020. http://www.nature.com/nrd/journal/v5/n8/full/nrd2117.html. 
  45. Cortez, Michelle Fay and Pettypiece, Shannon. "Merck Cancer Shot Cuts Genital Warts, Lesions in Men". Bloomberg News. (Bloomberg.com) 13 Nov 2008.
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