Risk factors for penile cancer
A risk factor is something that increases the risk of developing cancer. It could be a behaviour, substance or condition. Most cancers are the result of many risk factors. But sometimes penile cancer develops in men who don’t have any of the risk factors described below.
Penile cancer is an uncommon cancer in Canada. It can develop at any age, but the risk for penile cancer usually increases with age. It most often happens in men older than 60 years of age.
Precancerous conditions of the penis include penile intraepithelial neoplasia (PeIN) and balanitis xerotica obliterans (BXO) (also called penile lichen sclerosus). They aren’t cancer, but they can sometimes become invasive penile cancer if they aren’t treated. Many of the risk factors for penile cancer may also cause these precancerous conditions. Find out more about precancerous conditions of the penis.
Risk factors are generally listed in order from most to least important. But in most cases, it is impossible to rank them with absolute certainty.
|Known risk factors||Possible risk factors|
Known risk factors
There is convincing evidence that the following factors increase your risk for penile cancer.
Most sexually active men will have at least one HPV infection in their lifetime. HPV is easily passed by skin-to-skin contact with any HPV-infected area of the body. More than 40 types of HPV are spread through sexual intercourse, genital skin-to-skin contact and oral sex. Certain sexual behaviours can increase the risk of HPV infection, including:
- becoming sexually active at a young age
- having many sexual partners
- having sex with a partner who has had multiple sexual partners
- having unprotected sex
Each type of HPV is considered either high risk or low risk for developing cancer. High-risk HPV types are more likely to lead to cancer. HPV-16 and HPV-18 are the most common high-risk types. They are linked to penile cancer. Low-risk HPV types, such as HPV-6 and HPV-11, rarely cause cancer, but they can cause warts on or around the genitals. Men with penile cancer often report having a history of genital warts. The exact role that these viruses play in the development of penile cancer is not clear.
In men who are not circumcised, the foreskin of the penis may become thick and tight and difficult to pull back (retract). This condition is called phimosis. Phimosis makes it harder to clean the penis well and may lead to infections or chronic inflammation.
Men with BXO often develop phimosis. They may have an even greater risk of developing penile cancer than men with phimosis alone.
Circumcision is removal of the foreskin. The age at circumcision appears to affect the risk for penile cancer. Men who were circumcised as newborns or children appear to have a lower incidence of penile cancer. Being circumcised as an adult does not appear to provide any protection against penile cancer.
Research suggests that circumcision may help promote better penile hygiene, cause less irritation or inflammation of the penis, and lower the risk for penile HPV infection. Circumcision prevents phimosis, which is also linked to penile cancer.
Although there is some evidence that circumcision lowers the risk for penile cancer, there is not enough evidence to recommend circumcision as a way of preventing cancer of the penis. The Canadian Paediatric Society does not recommend routine circumcision of every newborn boy. Decisions about circumcision are highly personal and often depend on religion and culture more than medical reasons.
When a man isn’t circumcised, a thick substance can build up under the foreskin. This substance is called smegma. It is made up of dead skin cells, bacteria and oily secretions.
Buildup of smegma can become worse if the penis isn’t cleaned properly. Having smegma can cause chronic irritation and inflammation of the penis, which increases the risk for penile cancer. Some studies also suggest that smegma may contain small amounts of cancer-causing substances, but there is no definite evidence for this.
A weakened immune system (also called immunosuppression) lowers the body’s ability to defend itself against infections, including HPV infection. The immune system can become weakened for many reasons, including:
- having HIV or AIDS
- taking certain drugs that suppress the immune system (called immunosuppressants) after an organ transplant
Psoriasis is a skin condition. Treatment for psoriasis may include taking the drug psoralen and then exposing the affected skin to ultraviolet light (called PUVA therapy). Men who had PUVA therapy have a higher risk of developing penile cancer.
Possible risk factors
The following factors have been linked with penile cancer, but there is not enough evidence to show they are known risk factors. More research is needed to clarify the role of these factors for penile cancer.
Smoking tobacco or using smokeless tobacco products (including chewing tobacco and snuff) may increase the chance of developing penile cancer. The risk seems to be highest in men who are heavy smokers and have smoked for a long time. Combining smoking with smokeless tobacco products may also increase the risk of penile cancer.
Researchers think that the chemicals in tobacco that cause cancer may damage the DNA in cells of the penis and increase the risk of developing cancer. The risk for cancer may also be higher because smoking increases the risk of an HPV infection not going away.
More research is needed to clarify the role that injury to the penis might have in the risk for penile cancer.
Unknown risk factors
It isn’t known whether or not the following factors are linked with penile cancer. It may be that researchers can’t show a definite link or that studies have had different results. More research is needed to see if the following are risk factors for penile cancer:
- persistent and painful erection (called priapism)
Questions to ask your healthcare team
To make the decisions that are right for you, ask your healthcare team questions about risks.
Referring to a procedure or device that breaks the skin or enters a body cavity.
Referring to a disease (such as cancer) that is growing into surrounding tissue or has spread outside the tissue where it started.
A type of virus that causes AIDS.
A disease caused by the human immunodeficiency virus (HIV) in which lymphocytes (a type of white blood cell that fights germs, foreign substances or cancer cells) are destroyed and the body cannot protect itself from infection.
People with AIDS are at an increased risk for developing certain cancers, including Kaposi sarcoma.
Also called acquired immunodeficiency syndrome.
I’m extremely grateful to the Canadian Cancer Society for funding my research with an Innovation Grant.
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