Information about the prevention of cancer and the science of
screening appropriate individuals at high-risk of developing cancer is
gaining interest. Physicians and individuals alike recognize that the
best “treatment” of cancer is preventing its occurrence in the first
place or detecting it early when it may be most treatable.
Uterine (endometrial) cancer is the most common invasive gynecologic
cancer in women, with 36,100 new cases each year. This incidence would
be higher if it weren’t for the relatively large number of
hysterectomies performed for non-cancerous reasons. It is estimated that
approximately 6,500 women will die of uterine cancer in the United
States each year. The lifetime risk of developing uterine cancer for an
American woman is 2%.
There has been an increase in the incidence of, but not mortality
from, uterine cancer since the mid 1970s, which has been attributed to
the use of hormone replacement therapy for treatment of menopausal
symptoms. Studies show that the most common type of uterine cancer,
endometroid adenocarcinoma, develops from the overgrowth of cells lining
the uterus in the setting of excessive or prolonged exposure to the
female hormone estrogen. Other less common uterine cancers, such as
serous carcinoma, do not seem to be related to estrogen levels in the
body.
The chance of an individual developing cancer depends on both genetic
and non-genetic factors. A genetic factor is an inherited, unchangeable
trait, while a non-genetic factor is a variable in a person’s
environment, which can often be changed. Non-genetic factors may include
diet, exercise, or exposure to other substances present in our
surroundings. These non-genetic factors are often referred to as
environmental factors. Some non-genetic factors play a role in
facilitating the process of healthy cells turning cancerous (i.e. the
correlation between smoking and lung cancer) while other cancers have no
known environmental correlation but are known to have a genetic
predisposition, meaning a person may be at higher risk for a certain
cancer if a family member has that type of cancer.
Heredity or Genetic Factors
Women with a family history of uterine cancer are twice as likely to
develop uterine cancer than women without a family history. Women who
have a family history of hereditary nonpolyposis colon cancer (HNPCC)
have an increased risk for carrying the HNPCC genetic abnormality.
Studies suggest that women who carry this genetic abnormality have a
10-fold increased risk of uterine cancer and a 20% incidence of uterine
cancer by the age of 70. Women with a family history of uterine cancer
may wish to discuss genetic testing with their physician. For more
information about genetic testing, please refer to the section
Genetic Testing.
Environmental or Non-Genetic Factors
Factors associated with an increased risk of developing uterine
cancer include obesity, a high-fat diet and a prolonged exposure to the
female hormone, estrogen. Women who begin to menstruate early in life,
experience a late menopause and/or have no children have the longest
exposure to estrogen, and are thus, at the highest risk. Completion of
at least one pregnancy appears to lower the risk of uterine cancer by
50%, as after the birth of the first child, the risk of developing
uterine cancer appears to decrease with increasing age. The risk also
decreases in proportion to the number of induced abortions. Women who
take oral contraceptives also appear to have a reduction in the
incidence of uterine cancer.
Hormone Replacement and Uterine Cancer: Women who
take estrogen replacement therapy to control menopausal symptoms have a 4
to 8-fold increase in the risk of developing uterine cancer. This risk
increases with the duration of use. For example, after 5 or more years
of estrogen use, the risk of developing uterine cancer increases to 10
to 30-fold. The risk appears to last for 10 years or more after
discontinuation of estrogen replacement therapy. When this information
was made public, there was a decline in the use of estrogen replacement
and a decline in the incidence of uterine cancer. However, women need to
consider all risks and benefits before discontinuing hormone
replacement for treatment of menopause because the benefits of hormone
replacement therapy may outweigh the risk of cancer.
There is some evidence that adding progesterone to estrogen for the
treatment of menopausal symptoms can decrease the risk of uterine cancer
that is presented by estrogen; however, there is also evidence that
this strategy increases the risk of breast cancer. The main issue for
women taking hormone replacement is to have periodic gynecologic
evaluations to detect early uterine cancer. With this strategy, women
can both achieve the benefits of hormone therapy and detect uterine
cancer early when it is small and curable.
Tamoxifen and Uterine Cancer: Tamoxifen is a
chemopreventive drug that blocks estrogen from entering the cells.
Tamoxifen and other anti-estrogens are commonly used in the treatment of
breast cancer, but have also proven successful in the prevention of
breast cancer in women at high-risk.
One uncommon complication of tamoxifen therapy is uterine cancer.
Several clinical studies around the world have evaluated the risks and
benefits of tamoxifen. The results of the National Cancer Institute
clinical study evaluating tamoxifen were presented in 1998. During this
study, 13,388 women at high risk of developing breast cancer were
treated with either tamoxifen or placebo for 5 years. While the results
indicated a 45% reduction in the development of breast cancer, they also
showed an increase in the risk of uterine cancer, as 33 women treated
with tamoxifen developed uterine cancer, compared with only 14 women in
the placebo group. All of the uterine cancers occurring in the tamoxifen
group were early stage I cancers.
Since the majority of uterine cancers will be detected at an early
stage when they are highly curable, the overall benefit of anti-estrogen
treatment in breast cancer patients probably outweighs the risk of
uterine cancer. All women who have a uterus and are receiving
anti-estrogen therapy should undergo regular gynecologic examinations.
Furthermore, in response to the risks posed by tamoxifen, newer
anti-estrogens have emerged. Selective estrogen receptor modulators
(SERM) are believed to have positive effects on bones as well as
anti-estrogen effects on breast cancer without increasing the risk of
uterine cancer. For more information, please refer to the section
Hormonal Therapy.
Prevention of Uterine Cancer
Cancer is largely a preventable illness. Two-thirds of cancer deaths
in the U.S. can be linked to tobacco use, poor diet, obesity, and lack
of exercise. All of these factors can be modified. Nevertheless, an
awareness of the opportunity to prevent cancer through changes in
lifestyle is still under-appreciated.
Decreasing body weight and reducing exposure to estrogen may decrease
the risk of developing uterine cancer. The addition of progesterone to
estrogen may also decrease the risk of developing uterine cancer in
women taking hormone replacement for menopausal symptoms. There is
evidence to suggest that the use of combined hormone therapy in the form
of oral contraceptives can also reduce the risk of uterine cancer by up
to 40% if used for at least a year.
Diet: Diet is a fertile area for immediate
individual and societal intervention to decrease the risk of developing
certain cancers. Numerous studies have provided a wealth of
often-contradictory information about the detrimental and protective
factors of different foods.
There is convincing evidence that excess body fat substantially
increases the risk for many types of cancer. While much of the
cancer-related nutrition information cautions against a high-fat diet,
the real culprit may be an excess of calories. Studies indicate that
there is little, if any, relationship between body fat and fat
composition of the diet. These studies show that excessive caloric
intake from both fats and carbohydrates lead to the same result of
excess body fat. The ideal way to avoid excess body fat is to limit
caloric intake and/or balance caloric intake with ample exercise.
It is still important, however, to limit fat intake, as evidence
still supports a relationship between cancer and polyunsaturated,
saturated and animal fats. Specifically, studies show that high
consumption of red meat and dairy products can increase the risk of
certain cancers. One strategy for positive dietary change is to replace
red meat with chicken, fish, nuts and legumes.
High fruit and vegetable consumption has been associated with a
reduced risk for developing at least 10 different cancers. This may be a
result of potentially protective factors such as carotenoids, folic
acid, vitamin C, flavonoids, phytoestrogens and isothiocyanates. These
are often referred to as antioxidants.
There is strong evidence that moderate to high alcohol consumption
also increases the risk of certain cancers. One reason for this
relationship may be that alcohol interferes with the availability of
folic acid. Alcohol in combination with tobacco creates an even greater
risk of certain types of cancer.
Exercise: Higher levels of physical activity may
reduce the incidence of some cancers. According to researchers at
Harvard, if the entire population increased their level of physical
activity by 30 minutes of brisk walking per day (or the equivalent
energy expenditure in other activities), we would observe a 15%
reduction in the incidence of colon cancer. The association between
exercise and uterine cancer is not as well defined.
Screening and Early Detection of Uterine Cancer
For many types of cancer, progress in the areas of cancer screening
and treatment has offered promise for earlier detection and higher cure
rates. The term
screening refers to the regular use of certain
examinations or tests in persons who do not have any symptoms of a
cancer but are at high-risk for that cancer. When individuals are at
high-risk for a type of cancer, this means that they have certain characteristics or exposures, called
risk factors
that make them more likely to develop that type of cancer than those
who do not have these risk factors. The risk factors are different for
different types of cancer. An awareness of these risk factors is
important because 1) some risk factors can be changed (such as smoking
or dietary intake), thus decreasing the risk for developing the
associated cancer; and 2) persons who are at high-risk for developing a
cancer can often undergo regular screening measures that are recommended
for that cancer type. Researchers continue to study which
characteristics or exposures are associated with an increased risk for
various cancers, allowing for the use of more effective prevention,
early detection, and treatment strategies.
Periodic gynecologic evaluation is crucial for the early detection of
uterine cancer. All women should undergo regular physical examinations
and patients on hormone replacement therapy or tamoxifen might consider
monitoring with transvaginal sonography (ultrasound examination) and
hysteroscopy (endoscopic evaluation of the uterus). The ability to
detect abnormalities in the uterus may be improved with a test called
sonohysterograpy, where a salt-water solution is infused into the uterus
before the transvaginal sonography is performed. This is a safe and
inexpensive improvement over conventional ultrasound examinations.
For women taking tamoxifen, annual examinations beginning 2-3 years
after the start of treatment are currently advised. Abnormal bleeding or
undiagnosed postmenopausal bleeding warrants immediate evaluation with
endometrial biopsy. Ultrasound performed through the vagina for the
evaluation of bleeding can also be used in some patients instead of
immediate biopsy.
Strategies to Improve Screening and Prevention
The potential for earlier detection and higher cure rates increases
with the advent of more refined screening techniques. In an effort to
provide more screening options and perhaps more effective prevention
strategies, researchers continue to explore new techniques for the
screening and early detection of cancer.
Predictive Genetic Testing: The identification of
the cancer susceptibility genes has led to predictive genetic testing
for these genes. Since most uterine cancers are not the result of known
inherited mutations, not all women would benefit from genetic testing.
However, women who have a family history of hereditary nonpolyposis
colon cancer (HNPCC) have an increased risk for carrying the HNPCC
genetic abnormality. These women may benefit from undergoing a test to
determine if they do carry the HNPCC genetic abnormality. An accurate
genetic test can reveal a genetic mutation, but cannot guarantee that
cancer will or will not develop. At this point, genetic tests are used
to identify individuals who are at an increased risk of developing
cancer, so that these individuals may have the option of taking
preventive measures. For more information about genetic testing, please
refer to the section
Genetic Testing.
Copyright © 2012
Omni Health Media Uterine Cancer Information Center. All Rights Reserved.
Source: National Foundation for Cancer Research
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