Risk factors for penile cancer
Any substance or condition that increases cancer risk is referred to as a risk factor. There isn’t a known, single cause of penile cancer. Most cancers are the result of many risk factors. However, some men with penile cancer do not have any identifiable risk factors.
*Risk factors are generally listed in order from most significant to least significant. In most cases, it is impossible to rank the relative significance of individual risk factors with absolute certainty.
The risk of penile cancer increases with age. Penile cancer occurs most often in men over age 60. However, it can occur at any age.
The following factors are known to increase the risk of developing penile cancer.
Infection with the human papillomavirus (HPV) is associated with penile cancer. Most sexually active men will be exposed to HPV at some time in their life.
HPV is easily passed by skin-to-skin contact with any HPV-infected area of the body. It is mainly spread through sexual contact. 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
Types of HPV
The types of HPV are often grouped into low and high risk according to their association with cancer. Low-risk HPV types such as 6 and 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. High-risk HPV types are more likely to lead to cancer. In particular, HPV types 16 and 18 are linked to penile cancer. The exact role that these viruses play in the development of penile cancer is not clear.
It is thought that HPV infection is a risk factor for precancerous conditions of the penis that have the potential to develop into cancer.
In men who are not circumcised, the foreskin of the penis may become 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 phimosis have a higher risk of penile cancer.
Penile cancer has been associated with poor genital hygiene. When a man isn’t circumcised, secretions can build up under the foreskin. Whitish secretions that build up under the foreskin are called smegma.
Buildup of smegma can become worse if the penis isn’t cleaned properly. If uncircumcised men do not pull back the foreskin and wash the entire penis well, smegma may cause chronic irritation and inflammation of the penis. Some studies suggest that smegma may contain cancer-causing substances, but there is no definite evidence for this. However, many healthcare professionals believe that cancer of the penis is more likely to develop when a man doesn’t keep his genitals clean.
Circumcision is removal of the foreskin of the penis. Men who aren’t circumcised have a higher risk of developing penile cancer. Men who were circumcised as newborns or children appear to have a lower incidence of penile cancer. The age when a male is circumcised appears to affect the risk 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, reduce inflammation associated with the buildup of secretions (smegma) and reduce the risk of penile HPV infection. Circumcision prevents phimosis, which is also linked to penile cancer.
Although there is some evidence that circumcision reduces the risk of 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 newborn boys. Decisions about circumcision are highly personal and depend more on religion and culture than on medical reasons.
A weakened immune system can increase a man’s risk of penile cancer. A weakened immune system lowers the body’s ability to defend itself against infections, such as HPV infection. The immune system can become weakened for a number of reasons, such as:
- Immunosuppressants are drugs that suppress the immune system. They are used to prevent rejection of an organ after a transplant.
- People with HIV/AIDS have a weakened immune system and a higher risk of developing many types of cancer.
Smoking can 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. The exact role that smoking plays in penile cancer is not known. Researchers think that the chemicals in cigarettes that cause cancer may damage the DNA of cells in the penis and increase the risk of developing cancer.
Psoriasis is a skin condition. Treatment for psoriasis may include taking the drug psoralen and then exposing the affected skin to ultraviolet light (PUVA treatmentPUVA treatmentA type of therapy that uses both psoralen (P) and ultraviolet A (UVA) radiation.). Men who have had this treatment have an increased risk of developing penile cancer.
The following factor has some association with penile cancer, but there is not enough evidence to say it is a known risk factor. Further study is needed to clarify the role of this factor for penile cancer.
- injury – Injury to and small tears or abrasions on the penis may increase the risk of penile cancer. While it isn’t known exactly how these contribute to penile cancer, it is thought that they may increase the chance of HPV infection.
The following is a factor for which there is not enough evidence or the evidence is inconclusive. In other words, it can't be determined for sure whether this risk factor is or is not associated with penile cancer.
- persistent painful erection (priapism)
Questions to ask your healthcare team
To make the decisions that are right for you, ask your healthcare team questions about risks.