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A risk factor is anything that increases
your chance of getting a disease such as cancer. Different cancers have
different risk factors. For example, exposing skin to strong sunlight
is a risk factor for skin cancer. Smoking is a risk factor for cancers
of the lung, mouth, larynx, bladder, kidney, and several other organs.
But having a risk factor, or even several, does not mean that you will
get the disease.
Scientists have found certain risk factors that make a man
more likely to develop penile cancer. Even if a person does have one or
more risk factors for penile cancer, it is impossible to know for sure
how much that risk factor contributes to causing the cancer. On the
other hand, some men who develop penile cancer have no known risk
factors.
Local Hygiene, Phimosis, and
Smegma
In men who are not circumsised and therefore, have an intact
foreskin, secretions can build up underneath. This can worsen with
improper cleaning. Sometimes the foreskin becomes constricted and
difficult to retract. This condition is known as phimosis. Oily
secretions from the skin, dead skin cells, and bacteria accumulate
under the foreskin. The result is a thick, sometimes odorous substance
called smegma. Some studies suggest that smegma may contain
cancer-causing substances, but most recent studies disagree. Still,
many doctors feel that when a man doesnÂ’t keep this area clean, he is
more likely to develop cancer of the penis.
Smegma alone is unlikely to have a significant impact, if
any, on your risk of developing penile cancer. Nonetheless, if
uncircumcised men do not retract the foreskin and thoroughly wash the
entire penis, the presence of smegma may cause irritation and
inflammation of the penis. Men with phimosis are less likely to clean
the penis routinely and effectively.
Human Papillomavirus Infection
Some researchers believe that infection with the human
papillomavirus (HPV) may be a risk factor for penile cancer.
HPVs are a group of more than 100 types of viruses called
papillomaviruses because they can cause warts, or papillomas. Different
HPV types cause different types of warts in various parts of the body.
Some types cause common warts on the hands and feet. Other types tend
to cause warts on the lips or tongue.
HPV is the major cause of cancer of the cervix in women and
thought to be responsible for cancer of the anus in men and women. It
may also be responsible for some cancers of the vagina and vulva in
women. HPV is passed from one person to another during sexual contact.
These factors can increase a person's risk of HPV infection.
- sexual intercourse at an early age
- having many sexual partners
- having sex with a partner who has had many other partners
- having unprotected sex (not using a condom)
When HPV infects the skin of the external (outer) genital
organs and anal area (around the opening of the intestinal tract), it
often causes raised, bumpy warts. These may be barely visible or may be
several inches across. The medical term for genital warts is condyloma
acuminatum. Two "low-risk" HPV types, HPV 6 and HPV 11, cause most
genital warts. These warts rarely develop into cancer. However, other
sexually transmitted HPVs have been linked with genital or anal cancers
in both men and women. These are called "high-risk" HPV types and
include HPV 16, HPV 18, HPV 33, HPV 35, HPV 45, as well as some others.
Smoking
Smoking increases the chance of developing penile cancer. If
you smoke, your body is exposed to many cancer-causing chemicals that
affect more than your lungs. These harmful substances are absorbed into
blood flowing through the lungs and carried in the bloodstream
throughout the body. Researchers believe that these substances damage
the DNA of cells in the penis and contribute to the development of
penile cancer, especially in men who also have HPV infections.
UV Light Treatment of Psoriasis
Men who have a skin disease called psoriasis and who have
been treated with a combination involving a drug called psoralen and
exposure to ultraviolet light have a higher rate of penile cancer.
Age
Age is a risk factor. Nearly two-thirds of cases of the
disease are diagnosed in men over age 65.
AIDS
Men with AIDS (acquired immunodeficiency syndrome) may have a
higher risk of penile cancer. Although this may be caused by their
lowered immune response, lifestyle factors may also play a role.
Not Being Circumcised
Circumcision is the removal of a part or all of the foreskin
at birth or later on in life. In the United States, men who are
circumcised in childhood have a lower rate of penile cancer. It’s not
known whether this is due to the absence of the foreskin or other
lifestyle factors. Recent studies have found that circumcised men are
less likely to be infected with HPV, even after this risk is adjusted
for differences in sexual behavior. Other studies suggest that
circumcision may reduce the risk of more invasive forms of penile
cancer. A recent study reported that uncircumcised men who had phimosis
in the past were at increased risk of developing penile cancer. Penile
cancer risk was not increased among uncircumcised men without phimosis.
However, it is important that the issue of circumcision not
distract men from avoiding known penile cancer risk factors -- poor
hygiene, phimosis, having unprotected sex with multiple partners
(increasing the likelihood of human papillomavirus infection), and
cigarette smoking.
In weighing the risks and benefits of circumcision, doctors
consider the fact that penile cancer is one of the least common forms
of cancer in the United States. Neither the American Academy of
Pediatrics nor the Canadian Academy of Pediatrics recommends routine
circumcision of newborns. Ultimately, decisions about circumcision are
highly personal and depend more on social and religious factors than on
medical evidence.
Revised: 05/31/2006
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