Download Risk Factors for Cancer

CANCER PREVENTIZON
CONFFERENCE
CANCER PREVENTION
Prevention is defined as the reduction of
cancer mortality via reduction in the incidence
of cancer.
 In addition to the physical problems and
emotional distress caused by cancer, the high
costs of care are also a burden to patients,
their families, and to the public
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CANCER PREVENTION
Many things in (1)our genes, ( 2)our lifestyle, and
the (3)environment around us may increase or
decrease our risk of getting cancer.
 Scientists are studying many different ways to help
prevent cancer, including the following:
 This can be accomplished by avoiding a
carcinogen or altering its metabolism; pursuing
lifestyle or dietary practices that modify cancercausing factors or genetic predispositions;
medical intervention (e.g., chemoprevention); or
early detection strategies that can result in
removal of precancerous lesions, such as
colonoscopy for colorectal polyps.
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CANCER: GENERAL ETIOLOGY AND
PATHOGENESIS
GENETIC CHANGES
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Genetic changes that increase cancer risk can be inherited from our
parents if the changes are present in germ cells, Such changes, called
germline changes, are found in every cell of the offspring.
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Cancer-causing genetic changes can also be acquired during one’s
lifetime, as the result of errors that occur as cells divide during a
person’s lifetime or exposure to substances, such as certain
chemicals in tobacco smoke, and radiation, such as ultraviolet rays
from the sun, that damage DNA.
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Genetic changes that occur after conception are called somatic
(or acquired) changes, they can arise at any time during a
person’s life
CANCER PREVENTION
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The model of Vogelstein and Kinzler
emphasizes that cancer is ultimately a disease
of damaged DNA, comprised of a series of
genetic mutations that can transform normal
cells to cancerous cells
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The genetic mutations include inactivation of
tumor suppressor genes and activation of
oncogenes
Alterations of Specific Cellular Functions
in Cancer
DNA Repair
Tumor Suppressor Genes
Oncogenes
Inactivation
Activation
Differentiation
Apoptosis/Proliferation
CANCER
GENETIC CHANGES
The most commonly mutated gene in all cancers is
TP53, which produces a protein that suppresses the
growth of tumors
 In addition, germline mutations in this gene can
cause Li-Fraumeni syndrome, a rare, inherited
disorder that leads to a higher risk of developing
certain cancers.
 Inherited mutations in the BRCA1 and BRCA2
genes are associated with hereditary breast and
ovarian cancer syndrome, which is a disorder
marked by an increased lifetime risk of breast and
ovarian cancers in women
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GENETIC CHANGES
Several other cancers have been associated with
this syndrome, including pancreatic and prostate
cancers, as well as male breast cancer.
 Another gene that produces a tumor suppressor
protein is PTEN
 Mutations in this gene are associated with
Cowden syndrome, an inherited disorder that
increases the risk of breast, thyroid, endometrial,
and other types of cancer.
 Inherited genetic mutations play a major role in
about 5 to 10 percent of all cancers
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GENETIC CHANGES
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Similar mutations would be expected to result
in cancer progression among all individuals;
however, in those without a major inherited
cancer predisposition, the mutation would
occur as a somatic mutation later during their
lifetime.
GENETIC CHANGES
The model of Hanahan and Weinberg focuses on
the hallmark events at the cellular level that lead
to a malignant tumor
 In this model, the hallmarks of cancer include
sustained angiogenesis, limitless replicative
potential, evading apoptosis, self-sufficiency in
growth signals, and insensitivity to antigrowth
signals, leading to the defining characteristics of
malignant tumors by giving them the ability to
invade and metastasize
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PROGRESSIVE ACQUISITION OF
NEOPLASTIC FEATURES
RISK FACTORS FOR CANCER
It is usually not possible to know exactly why one
person develops cancer and another doesn’t
 (There are also factors that are linked to a lower
risk of cancer
These are sometimes called protective risk factors,
or just protective factors)
 Cancer risk factors include exposure to chemicals
or other substances, as well as certain behaviors.
 They also include things people cannot control, like
age and family history.
 A family history of certain cancers can be a sign of a
possible inherited cancer syndrome
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RISK FACTORS CAUSALLY ASSOCIATED WITH
CANCER
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Tobacco use is a leading cause of cancer and of death
from cancer
People who use tobacco products or who are regularly
around environmental tobacco smoke (also called
secondhand smoke) have an increased risk of cancer
because tobacco products and secondhand smoke have
many chemicals that damage DNA
Tobacco use causes many types of cancer, including
cancer of the lung, larynx (voice box), mouth,
esophagus, throat, bladder, kidney, liver, stomach,
pancreas, colon and rectum, and cervix, as well as
acute myeloid leukemia
People who use smokeless tobacco (snuff or chewing
tobacco) have increased risks of cancers of the mouth,
esophagus, and pancreas.
RISK FACTORS CAUSALLY ASSOCIATED WITH
CANCER
There is no safe level of tobacco use
 People who use any type of tobacco product are
strongly urged to quit
 People who quit smoking, regardless of their age,
have substantial gains in life expectancy
compared with those who continue to smoke
 Also, quitting smoking at the time of a cancer
diagnosis reduces the risk of death
 Cigarette smoking causes 30% of all cancer
deaths in the United States
 Smoking avoidance and smoking cessation result
in decreased incidence and mortality from cancer.
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INFECTIONS
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Certain infectious agents, including viruses, bacteria, and
parasites, can cause cancer in infected people or increase
the risk that cancer will form
Some viruses can disrupt normal controls on cell growth
and proliferation
They may also increase the chance that a person will be
affected by other cancer risk factors, such as UV
radiation or substances in tobacco smoke that cause
cancer
Some viruses, bacteria, and parasites also cause chronic
inflammation, which may lead to cancer.
You can lower your risk of infection by getting vaccinated,
not having unprotected sex, and not sharing needles.
INFECTIONS
If an infectious agent is truly a cause of cancer,
then efficacious, anti-infective interventions
would be expected in most instances to be
effective cancer prevention interventions
 This is the expectation with vaccines that protect
against infection with oncogenic strains of HPV.
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INFECTIONS
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Globally, infectious agents have been estimated to cause
18% of all cancer cases
The burden of cancers caused by infections is much
greater in developing nations (26%) than in developed
nations (8%).
Infection with an oncogenic strain of human
papillomavirus (HPV) is considered a necessary
event for subsequent cervical cancer, and vaccineconferred immunity results in a marked decrease in
precancerous lesions.
Oncogenic strains of HPV are also linked with cancers of
the penis, vagina, anus, and oropharynx.
HUMAN PAPILLOMAVIRUS (HPV)
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In the United States, experts recommend that children ages
11 and 12 receive a vaccine that prevents infection with the
types of HPV that cause most HPV-associated cancers
HPV infections in the cervix can be found with specific
tests
Because HPV is transmitted during sexual activity, there
is an association between an increased risk for cervical
cancer, the beginning of sexual activity at a younger age,
and with a greater number of lifetime sexual partners
Immunosuppression is another risk factor for cervical
cancer; for example, coinfection with human
immunodeficiency virus may lead to long-term
persistence of viral infection
INFECTIONS
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Other examples of infectious agents that cause cancer are
hepatitis B and hepatitis C viruses (liver cancer), EpsteinBarr virus (Burkitt lymphoma), and Helicobacter pylori
(gastric cancer).
If an infectious agent is truly a cause of cancer, then
efficacious, anti-infective interventions would be
expected in most instances to be effective cancer
prevention interventions
This is the expectation with vaccines that protect
against infection with oncogenic strains of HPV.
An example in which this principle would not hold true is
that in the setting of antibiotic resistance, the use of
antibiotics may not prevent carcinogenesis from cancercausing bacteria
INFECTIONS
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Hepatitis B Virus and Hepatitis C Virus (HBV and HCV)
Chronic infections with HBV or HCV can cause liver
cancer
Since the 1980s, infants in most other countries have
been routinely vaccinated against HBV infection
If you are an adult who has not been vaccinated against
HBV and have an increased risk of HBV infection,
experts recommend that you get vaccinated as soon as
possible
Vaccination is especially important for healthcare
workers and other professionals who come into contact
with human blood
INFECTIONS
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Human Immunodeficiency Virus (HIV)
Infection with HIV weakens the immune system and
makes the body less able to fight off other infectious
agents that cause cancer
People infected with HIV have an increased risk of
Kaposi sarcoma, lymphoma, and cancers of the cervix,
liver, lung, and anus.
Epstein-Barr Virus (EBV) Infection with EBV, a type of
herpes virus, has been linked to an increased risk of
lymphoma and cancers of the stomach and
nasopharynx
Human T-cell Leukemia/Lymphoma Virus Type 1 (HTLV1) HTLV-1 can cause a type of leukemia and lymphoma.
INFECTIONS
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Schistosoma hematobium
This flatworm (fluke), which is found in Africa and the
Middle East, can cause bladder cancer.
Opisthorchis viverrini
This flatworm (fluke), which is found in Southeast Asia,
can cause cholangiocarcinoma (cancer of the bile ducts
in the liver).
Merkel Cell Polyomavirus (MCPyV)
MCPyV can cause Merkel cell carcinoma, which is a rare
type of skin cancer.
Helicobacter pylori (H. pylori)
H. pylori is a type of bacteria that can cause stomach
cancer and a type of lymphoma in the stomach lining.
RADIATION
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Radiation of certain wavelengths, called ionizing radiation, has enough energy
to damage DNA and cause cancer.
Ionizing radiation includes radon, x-rays, gamma rays, and other forms of
high-energy radiation
Lower-energy,
non-ionizing forms of radiation, such as visible light and the energy from cell
phones and magnetic fields, do not damage DNA and have not been found to
cause cancer.?????
Radon is a radioactive gas given off by rocks and soil
Radon is formed when the radioactive element radium breaks down
Radium in turn is formed when the radioactive elements uranium and thorium
break down
People who are exposed to high levels of radon have an increased risk of lung
cancer.
If you live in an area of the country that has high levels of radon in its rocks and
soil, you may wish to test your home for this gas
RADIATION
Ionizing radiation : At low doses (e.g., those
associated with background radiation), the cells
repair the damage rapidly.
At moderate doses, the cells may be changed
permanently or die from their inability to repair the
damage
 Cells changed permanently may go on to produce
abnormal cells when they divide, and in some
circumstances, these altered cells may become
cancerous or lead to other abnormalities (e.g., birth
defects)
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RADIATION
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X-Rays and Other Sources of Radiation
High-energy radiation, such as x-rays, gamma rays,
alpha particles, beta particles, and neutrons, can
damage DNA and cause cancer
These forms of radiation can be released in accidents
at nuclear power plants and when atomic weapons are
made, tested, or used.
Certain medical procedures, such as chest x-rays,
computed tomography (CT) scans, positron emission
tomography (PET) scans, and radiation therapy can also
cause cell damage that leads to cancer
Limiting unnecessary CT scans and other diagnostic
studies
RADIATION
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However, the risks of cancer from these medical
procedures are very small, and the benefit from having
them is almost always greater than the risks.
Exposure to solar UV radiation is the major cause of
nonmelanoma skin cancers, which are by far the most
common malignancies in human populations.
There is extensive epidemiologic and biologic evidence
that links exposure to ionizing radiation with the
development of cancer, and in particular, cancer that
involves the hematological system, breast, lungs, and
thyroid.
The National Research Council of the National
Academies: no dose of radiation should be considered
completely safe
IMMUNOSUPPRESSION
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Medications that suppress the immune system,
commonly used, for example, in patients
undergoing organ transplantation, are
associated with an increased cancer risk.
RISK/PROTECTIVE FACTORS WITH UNCERTAIN
ASSOCIATIONS WITH CANCER
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Diet ; In contrast to the epidemiologic evidence on
cigarette smoking and cancer, evidence for the influence
of dietary factors and cancer is uncertain
Observational epidemiologic studies (case-control and
cohort studies) have suggested associations between
diet and cancer development, but randomized trials of
interventions provided little or no support
An assessment of the overall evidence of diet in relation
to cancer prevention published by the World Cancer
Research Fund/American Institute for Cancer
Research (WCRF/AICR).
RISK/PROTECTIVE FACTORS WITH UNCERTAIN
ASSOCIATIONS WITH CANCER
With respect to dietary factors that may protect
against cancer, the greatest consistency was seen
for fruits and nonstarchy vegetables
 In the WCRF/AICR report, conclusions were
reached that both fruits and nonstarchy
vegetables were associated with “probable
decreased risk” for cancers of the mouth,
esophagus, and stomach.
 Fruits, but not nonstarchy vegetables, were also
judged to be associated with “probable decreased
risk” of lung cancer
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RISK/PROTECTIVE FACTORS WITH UNCERTAIN
ASSOCIATIONS WITH CANCER
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For example, on the basis of population-based
epidemiologic data, high-fiber diets were recommended
to prevent colon neoplasms
However, a randomized, controlled trial of supplemental
wheat bran fiber did not reduce the risk of subsequent
adenomatous polyps in individuals with previously
resected polyps
Ecologic, cohort, and case-control studies found an
association between fat and red meat intake and colon
cancer risk, but a randomized, controlled trial of a lowfat diet in postmenopausal women showed no reduction
in colon cancer
The low-fat diet did not affect all-cancer mortality,
overall mortality, or cardiovascular disease.
ALCOHOL
With respect to dietary factors that may
increase cancer risk, the strongest evidence in
the WCRF/AICR report was for drinking alcohol
 Drinking alcohol can increase your risk of
cancer of the mouth, throat, esophagus, larynx
(voice box), liver, and breast ,colorectal cancer
 The more you drink, the higher your risk
 The risk of cancer is much higher for those who
drink alcohol and also use tobacco.
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AGE
Advancing age is the most important risk factor for
cancer overall, and for many individual cancer
types
 According to the most recent statistical data from
NCI’s Surveillance, Epidemiology, and End Results
program, the median age of a cancer diagnosis is
66 years
 This means that half of cancer cases occur in
people below this age and half in people above
this age
 One-quarter of new cancer cases are diagnosed in
people aged 65 to 74.
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PHYSICAL ACTIVITY
A growing body of epidemiologic evidence
suggests that people who are more physically
active have a lower risk of certain malignancies
than those who are more sedentary
 In the WCRF/AICR report, the evidence was judged
to be “convincing” that increased physical activity
protects against CRC
 The evidence was also judged to be “probable”
that physical activity was associated with lower
risk of postmenopausal breast cancer and
endometrial cancer.
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CHRONIC INFLAMMATION
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Inflammation is a normal physiological response that causes
injured tissue to heal
In response, white blood cells make substances that cause
cells to divide and grow to rebuild tissue to help repair the
injury
Chronic inflammation may be caused by infections that don’t
go away, abnormal immune reactions to normal tissues
Over time, chronic inflammation can cause DNA damage
and lead to cancer. For example, people with chronic
inflammatory bowel diseases, such as ulcerative colitis and
Crohn disease, have an increased risk of colon cancer.
Many studies have investigated whether anti-inflammatory
medications, such as aspirin or non-steroidal antiinflammatory drugs, reduce the risk of cancer.
SUNLIGHT
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The sun, sunlamps, and tanning booths all give off ultraviolet
(UV) radiation
Exposure to UV radiation causes early aging of the skin and
skin damage that can lead to skin cancer.
People of all ages should limit the amount of time they spend
in the sun, especially between mid-morning and late afternoon,
and avoid other sources of UV radiation, such as tanning beds
It is important to keep in mind that UV radiation is reflected by
sand, water, snow, and ice and can go through windshields and
windows.
The best way to lessen UV damage when spending time in the
sun is to wear long sleeves, long pants, a hat with a wide brim,
and sunglasses with lenses that absorb UV radiation
Sunscreen with a sun protection factor (SPF) of at least 15 may
help prevent skin cancer but does not work as well as staying
out of the sun and wearing protective clothing
OBESITY
Obesity is being increasingly recognized as an
important cancer risk factor
 The WCRF/AICR report concluded that obesity is
convincingly linked to postmenopausal breast
cancer and cancers of the esophagus, pancreas,
colorectum, endometrium, and kidney.
 Furthermore, the WCRF/AICR report judged body
fatness to be a probable risk factor for cancer of
the gallbladder.
 Furthermore, weight loss has yet to be shown to
reduce risk of obesity-associated malignancies?
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DIABETES
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Observational studies suggest that all-cancer incidence
and mortality are slightly increased (10%–15%) in
individuals with diabetes, although the increase is
greater for certain organ sites and null for others
At least four of the following characteristics of diabetes
have been hypothesized to increase cancer
risk:Hyperinsulinemia ,Hyperglycemia,Downregulation of
sex hormone–binding globulin,Chronic inflammation.
Diabetes and cancer share a number of risk factors,
including aging, obesity, smoking, unhealthy diet, and
physical inactivity
DIABETES
In prospective observational studies, risk of
and death due to liver, pancreas,
colon/colorectum, and female breast cancer
are consistently higher in persons with
diabetes.
 Increases in risk or death also have been
observed for cancer of the endometrium,
ovary, bladder, and oral cavity/pharynx
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DIABETES
Metformin has been associated with a decrease in
breast cancer incidence and mortality in
observational studies and is currently under study in
clinical trials
 Metformin has been hypothesized to reduce risk
by inhibiting tumor cell growth and proliferation
through adenosine monophosphate (AMP)–kinase
activation
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Long-term use of exogenous, long-acting insulin
has never consistently been shown to increase
cancer risk.
INTERVENTIONS WITH PROVEN BENEFITS
(CHEMOPREVENTION)
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Estrogens have essential physiological roles in both females
and males, they have also been associated with an
increased risk of certain cancers
Menopausal hormone therapy with estrogen alone increases
the risk of endometrial cancer and is used only in women
who have had a hysterectomy.
Studies have also shown that a woman’s risk of breast
cancer is related to the estrogen and progesterone made by
her ovaries (known as endogenous estrogen and
progesterone)
Increases in exposure can be caused by starting
menstruation early, going through menopause late, being
older at first pregnancy, and never having given birth
Conversely, having given birth is a protective factor for
breast cancer.
INTERVENTIONS WITH PROVEN
BENEFITS(CHEMOPREVENTION)
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Daily use of selective estrogen receptor modulators
(tamoxifen or raloxifene) for up to 5 years reduces the
incidence of breast cancer by about 50% in high-risk
women.
Finasteride (an alpha-reductase inhibitor) lowers the
incidence of prostate cancer; this finding was
complicated by a greater cumulative incidence of highgrade cancers in the finasteride-versus-placebo-group.
Further analysis suggests this was caused by
finasteride's ability to shrink the prostate but not the
cancer, thereby increasing the ability to diagnose highgrade cancer without contributing to progression of
prostate carcinogenesis
Dutasteride has also been shown to reduce the
incidence of prostate cancer
INTERVENTIONS WITH PROVEN
BENEFITS(CHEMOPREVENTION)
Other chemoprevention candidates include
COX-2 inhibitors and aspirin
 There is evidence to suggest that COX-2
inhibitors prevent colon and breast cancer, but
the possibility of increased cardiovascular
events may preclude their usefulness
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ENVIRONMENTAL EXPOSURES AND
POLLUTANTS
The relationship between environmental pollutants
and cancer risk has been of long-standing interest
to researchers and the public
 Nevertheless, some associations between
environmental pollutants and cancer have been
clearly established
 Perhaps because the lung is most heavily exposed
to air pollutants, many of the most firmly
established examples of pollutants and cancer
relate specifically to lung cancer, including
secondhand tobacco smoke, indoor radon,
outdoor air pollution, and asbestos for
mesothelioma
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ENVIRONMENTAL EXPOSURES AND
POLLUTANTS
Another environmental pollutant linked with
cancer is highly concentrated inorganic arsenic
in drinking water, which is causally associated
with cancers of the skin, bladder, and lung
 Many other environmental pollutants, such as
pesticides, have been assessed for risk with
human cancer, but with indeterminate results
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INTERVENTIONS WITH PROVEN
BENEFITS(CHEMOPREVENTION)
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While several agents, including alpha-tocopherol,
selenium, lycopene, vitamin D, isoflavonoids,
difluoromethylornithinehave shown potential in
either clinical or laboratory studies for
chemoprevention of prostate cancer, the
correlations of cancer prevention with these
agents are increasingly of concern given the
statistically increased risk of prostate cancer with
alpha-tocopherol in the SELECT trial and the
lack of preventive effect (actually, a nonsignificant increase in prostate cancer risk) with
selenium.
CHEMOPREVENTION WITH SELENIUM AND
VITAMIN E
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The Selenium and Vitamin E Cancer Prevention Trial
(SELECT [NCT00006392]) was a large randomized
placebo-controlled trial of vitamin E and selenium
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It showed no reduction in prostate cancer period
prevalence, but an increased risk of prostate cancer with
vitamin E alone
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Compared with the placebo group in which 529 men
developed prostate cancer, there was a statistically
significant increase in prostate cancer in the vitamin E
group (620 cases), but not in the selenium plus vitamin E
group (555 cases) or in the selenium group (575 cases)
CHEMOPREVENTION WITH LYCOPENE
Evidence exists that a diet with a high intake of fruits
and vegetables is associated with a lower risk of
cancer
 One group of nutrients often postulated as having
chemoprevention properties is the carotenoids
 Lycopene is the predominant circulating
carotenoid in Americans and has a number of
potential activities, including an antioxidant effect
 It is encountered in a number of vegetables, most
notably tomatoes, and is best absorbed if these
products are cooked
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WHO IS AT RISK?
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Endometrial cancer is a disease that primarily affects
postmenopausal women at an average age of 60 years at
diagnosis
Risk factors include postmenopausal estrogen therapy,
endometrial hyperplasia, obesity, reproductive factors like
nulliparity, early menarche and late menopause,
polycystic ovarian syndrome, and tamoxifen use
Women with hereditary nonpolyposis colorectal cancer
syndrome have a markedly increased risk of endometrial
cancer compared with women in the general population
Women with a family history of endometrial cancer in a
first-degree relative are also at increased risk.
WHO IS AT RISK?
Smoking and drinking alcohol may account for
roughly 90% of esophageal squamous cell
carcinoma cases in Western countries like the
United States
 Gastroesophageal reflux/Barrett esophagus is
associated with an increased risk of esophageal
adenocarcinoma
 Other factors that may explain the increased risk
of adenocarcinoma of the esophagus include
obesity and the use of medications such as
anticholinergics that can predispose to
gastroesophageal reflux disease (GERD) by
relaxing the lower esophageal sphincter
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WHO IS AT RISK?
Strong evidence that hepatocellular cancer (HCC)
can be prevented is provided by a study of
immunization to prevent transmission of hepatitis
B from infected mothers to their children,
suggesting that if hepatitis can be prevented, then
much HCC can be prevented
 Immunization programs are justified for
preventing important short-term consequences of
hepatitis B infection, such as acute hepatitis,
chronic hepatitis, and cirrhosis
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WHO IS AT RISK?
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Lung cancer risk is largely a function of older age combined with
extensive cigarette smoking history
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In nonsmokers, important lung cancer risk factors are exposure to
secondhand smoke, exposure to ionizing radiation, and occupational
exposure to lung carcinogens, such as asbestos
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Radiation exposures relevant to the general population include
environmental exposure to radon and radiation exposures
administered in the medical care setting, particularly when
administered at high doses, such as radiation therapy to the chest or
breast
Cigarette smoking often interacts with these other factors
There are several examples, including radon exposure and asbestos
exposure, in which the combined exposure to cigarette smoke plus
another risk factor results in an increase in risk that is much greater
than the sum of the risks associated with each factor alone.
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WHO IS AT RISK?
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Oral cavity cancer and oropharyngeal cancer
People who use tobacco in any of the commonly available
forms (cigarettes, cigars, pipes, and smokeless tobacco)
or a have high alcohol intake are at elevated risk of both
cancers; they are at particularly high risk if they use both
tobacco and alcohol
People who chew betel quid (whether mixed with tobacco
or not) are also at high risk of cancer of the oral cavity and
oropharynx
People who have a personal history of cancer in the
head and neck region also are at elevated risk of a
future primary cancer of the oral cavity or oropharynx
Human papillomavirus (HPV) 16 is a sufficient, but not
necessary, cause of oropharyngeal cancer
RISK FACTORS FOR CANCER
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Breast cancer
Reproductive factors that increase exposure to
endogenous estrogen, such as early menarche and late
menopause, use of combination estrogen-progesterone
hormones after menopause, women whose first
pregnancy occurs late in life
Nulliparity and alcohol consumption also are associated
with increased risk.
Women with a family history or personal history of
invasive breast cancer, ductal carcinoma in situ or
lobular carcinoma in situ, or a history of breast biopsies
that show benign proliferative disease have an
increased risk of breast cancer.
Increased breast density is associated with increased
risk
WHO IS AT RISK?
Ovarian cancer is rare
 The incidence rate for ovarian cancer between
2006 and 2010 was 12.5 cases per 100,000
women
 Women with a family history of ovarian cancer are
at increased risk, and those with an inherited
predisposition to ovarian cancer, such as a BRCA1
or BRCA2 mutation, have a very high risk of
developing ovarian cancer, Other risk factors
include obesity, nulliparity, and use of
postmenopausal hormone therapy
 Factors associated with a decreased risk of
ovarian cancer include use of oral contraceptives,
multiple pregnancies, breast-feeding, and tubal
ligation
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WHO IS AT RISK?
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People at elevated risk for gastric cancer include elderly
patients with atrophic gastritis or pernicious anemia,
patients with sporadic gastric adenomas, familial
adenomatous polyposis,or hereditary nonpolyposis colon
cancer,and immigrant ethnic populations from countries with
high rates of gastric carcinoma
Workers in the rubber and coal industries are also at
increased risk
Risk factors for gastric cancer include the presence of
precursor conditions such as chronic atrophic gastritis and
intestinal metaplasia, pernicious anemia, and gastric
adenomatous polyps. Genetic factors include a family history
of gastric cancer, Li Fraumeni syndrome, and Type A blood
type
WHO IS AT RISK?
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Environmental factors include low consumption of fruits
and vegetables; consumption of salted, smoked, or poorly
preserved foods; cigarette smoking; and radiation
exposure
There is consistent evidence that Helicobacter pylori
infection, also known as H. pylori infection, of the stomach
is strongly associated with both the initiation and
promotion of carcinoma of the gastric body and antrum
and of gastric lymphoma
The International Agency for Research on Cancer
classifies H. pylori infection as a cause of noncardia gastric
carcinoma and gastric low-grade B-cell mucosa-associated
lymphoid tissue or MALT lymphoma (i.e., a Group 1
human carcinogen).
WHO IS AT RISK?
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Individuals whose skin freckles, burns easily after sun
exposure are particularly susceptible to developing skin
cancer
Observational and analytic epidemiologic studies have
consistently shown that increased cumulative sun
exposure is a risk factor for nonmelanoma skin cancer
Organ transplant recipients receiving
immunosuppressive drugs are at an elevated risk of skin
cancer, particularly squamous cell carcinoma (SCC).
Arsenic exposure also increases the risk of cutaneous
SCC
In the case of melanoma, it seems that intermittent
acute sun exposure leading to sunburn is more
important than cumulative sun exposure; such
exposures during childhood or adolescence may be
particularly important