September 2005
September is Prostate Awareness Month
Prostate carcinoma is by far the most common
cancer affecting American males, with an estimated 232,090
new cases in the United States for 2005, according to the
American Cancer Society. Fortunately, prostate cancer is
often a slow growing malignancy, so the number of estimated
deaths from prostate carcinoma in the United States for
2005 is 30,350, far less than the number of new cases. In
contrast, lung cancer, an aggressive malignancy, will be
diagnosed in an estimated 172,570 men and women, resulting
in 163,510 deaths.
The cause of prostate carcinoma is unknown.
Approximately 5 percent to 10 percent of prostate cancers
are thought to be related to inherited genes that make some
men more susceptible. Even if a man does not inherit a genetic
susceptibility, mutations in normal genes, which are not
well characterized, lead to the development of prostate
cancer. Environmental exposures (like smoking) are related
to many cancers, but a clear link between the environment
and prostate carcinoma has not been established. There is
some evidence that high levels of male hormones (like testosterone)
or high levels of a hormone related to normal cell growth
(insulin-like growth factor-1) increase the risk of prostate
cancer, but other studies have not found this association.
Although the cause of prostate cancer is not
known, there are several factors that can increase the risk
of prostate cancer. Many men with these risk factors do
not get prostate cancer, and prostate cancer can develop
in men who do not have any risk factors.
- The risk of prostate cancer increases after age 50.
About two thirds of prostate cancer develops after the
age of 65, and it is thought that if a man lives long
enough, the disease is inevitable, although prostate
cancers developing in elderly men are usually not life
threatening.
- African-American men are more likely to develop prostate
cancer compared to whites and are more likely to be
diagnosed at an advanced stage. Asian men are less likely
to develop prostate cancer compared to whites. Hispanics
and whites have approximately the same risk.
- Prostate cancer is more common in North America and
northwestern Europe, compared to Asia, Africa, Central
America and South America.
- Men with brothers or fathers with prostate cancer
are more likely to develop the disease especially if
their relative developed it at a young age.
- Diets high in fat and red meat result in a slightly
higher risk of prostate carcinoma. These diets also
tend to contain fewer fruits and vegetables, which may
also be related to an increase in prostate cancer risk.
- Earlier studies suggested an increased risk of prostate
cancer after a vasectomy, but more recent studies have
not found an increased risk.
There are no easy ways to prevent the development
of prostate carcinoma. A moderate diet, which is high in
fruits, vegetables, beans, and whole grain products, and
low in red meat and fat, may lower the risk of prostate
cancer. Even if this type of diet has minimal effects on
the risk of prostate carcinoma, it may reduce the risk of
other cancers and more certainly, decrease the risk of other
health problems like cardiac disease or diabetes.
Lycopenes
(found in tomatoes, tomato products, pink grapefruit, and
watermelon), vitamin E, and selenium may lower the risk
of prostate carcinoma, but this is not certain. A trial
of 32,000 men is ongoing to see if selenium and vitamin
E can lessen the risk of prostate carcinoma. Studies do
not always support clinical observations, hoswever. Moderate
intake of supplements and vitamins (at the daily recommended
doses) is probably the wisest choice.
After prostate cancer develops, there are
a number of treatment options. For early stage disease,
surgery (prostatectomy) and radiation (external beam radiation
or radioactive implants) are viable alternatives. For younger,
healthy patients with a greater than 15 year life expectancy,
surgery is probably a better choice. For more advanced disease
that has not spread outside the prostate or the immediate
vicinity, radiation usually combined with hormonal therapy
is the preferred treatment.
Over the past several years, technical enhancements
to the delivery of radiation have decreased the side effects
from treatment and allowed higher doses of radiation to
be delivered to increase the success of radiation. Three-dimensional
(3-D) conformal radiation uses a 3-D representation of the
patient, tumor, and normal structures to target the tumor
and minimize dose to surrounding structures. Intensity modulated
radiation therapy (IMRT) is a subset of 3-D conformal radiation
in which each radiation beam is modulated so that dose to
the normal structures surrounding the prostate are reduced
even further. With IMRT, more radiation dose can be safely
delivered to the prostate that results in a greater number
of cures.
