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No, cancer is NOT contagious.
Cancer is not contagious. A healthy person cannot "catch"
cancer from someone who has it. There is no evidence that close contact
or things like sex, kissing, touching, sharing meals, or breathing the
same air can spread cancer from one person to another.
Cancer cells from one person are generally unable to live in
the body of another healthy person. The person's immune
system recognizes the cancer cells and destroys them. There have been a
few cases in which organ transplants from people with cancer have been
able to cause cancer in the transplant recipient. But there is a major
factor that makes this possible -- people who get organ transplants
must take medicines that weaken their immune systems to keep them from
destroying the transplanted organ. This seems to be a reason a
cancerous organ transplant can, in rare situations, give cancer to the
person who gets the organ. And careful screening is done to help keep
this from happening.
Even during pregnancy, cancer rarely affects the fetus
directly. Some cancers can spread from the mother to the placenta (the
organ that connects the mother to the fetus), but most cancers cannot
affect the fetus itself. In a few, very unusual cases, malignant
melanoma has been found to spread to the placenta and the fetus.
Germs can be contagious.
Of course, germs (mainly bacteria and viruses) can be passed
between people by sex, kissing, touching, sharing meals, or breathing
the same air. But germs are much more likely to pose a threat to a
person with cancer than to a healthy person. This is because people
with cancer often have weakened immune systems (especially when they
are getting treatment), and they may not be able to fight off
infections very well.
Germs can affect cancer risk.
There are a few germs that can play a role in the development
of certain types of cancer. This may lead some people to wrongly think
that "cancer is catching."
We know that some forms of cancer are found more often in
people who are infected with certain viruses. For example:
- Certain types of human papilloma viruses (HPVs) are linked
to cancers of the cervix, vagina, vulva, penis, and anus. Newer studies
suggest that HPV may also be linked to some cancers of the mouth,
throat, head, and neck. But smoking, alcohol use, and other factors
increase the risk of these cancers, too.
- Human T-lymphotrophic virus-1 (HTLV-1) is linked with
certain types of lymphocytic leukemia and non-Hodgkin lymphoma (NHL).
- Hepatitis B virus (HBV) and hepatitis C virus (HCV)
infections are linked to liver cancer (hepatocellular carcinoma).
- Human herpes virus Type 8 (HHV-8), also called Kaposi
sarcoma herpes virus (or KSHV), is linked with a type of cancer called
Kaposi sarcoma. Most people with HHV-8 do not develop Kaposi sarcoma
unless they are also infected with human immunodeficiency virus (HIV),
the virus that causes AIDS, or are taking medicines that weaken their
immune systems (such as after an organ transplant).
- Invasive cervical cancer, Kaposi sarcoma, and certain
lymphomas are much more common in people who are infected with the
human immunodeficiency virus (HIV), the virus that causes AIDS. In many
cases of HIV-related cancer, other viruses (such as HHV-8 or HPV) also
play a major role in the cancer's growth and development.
- Epstein-Barr virus (EBV) is linked to nose and throat
(nasopharyngeal) cancer, stomach cancer, and some lymphomas.
These viruses may be passed from person to person (usually
through blood or through sexual contact), but the viral infection alone
usually does not lead to cancer. It appears that viruses need to be
"triggered" by another agent (or agents) before a cancer can develop.
Bacteria and parasites can also promote cancer. Helicobacter pylori
is a common bacterium now known to be linked to certain kinds of cancer
in the stomach. Long-term infection with these bacteria can damage the
inner layer of the stomach and raise the risk of stomach cancer and
lymphoma of the stomach.
Certain parasitic worms that can live inside the human body
can also raise the risk of developing some kinds of cancer. Parasites
that can cause cancer are rarely found in the United States or other
developed countries, but they are linked with cancer of the bladder and
the bile ducts, and possibly other cancers, too.
Most cancers are not linked to germs or
infection.
Most cancers do not appear to be caused or influenced by
infectious agents. Cancer develops because of mutations (changes) that
take place in a person's DNA, the genetic blueprint within
each cell. These changes are inherited or develop during life, either
spontaneously or due to the effects of environmental agents (such as
sun exposure or cigarette smoke). Some viruses are known to directly
cause mutations in DNA that can develop into cancer. Other germs
promote cancer indirectly by causing chronic (long-term) inflammation,
or by weakening a person's immune system. For more information, see our
documents, What Is Cancer
and Infectious Agents and Cancer.
Scientific studies of cancer causes show
that there is no way cancer can be considered contagious.
If cancer were contagious, we would have cancer epidemics just
as we have flu epidemics -- cancer would spread like measles, polio, or
the common cold. We would expect a high rate of cancer among the
families and friends of cancer patients and among health professionals
to reflect their exposure to the disease. This is not the case.
The fact that cancer may happen more often in certain families
does not mean that the family members may have spread cancer to each
other. The reasons this sometimes happens are related to having the
same genes, similar unhealthy lifestyles (diet and smoking, for
example), or exposure to the same cancer-causing agent in the family's
environment.
Some people point to "clusters" of cancer patients who have
had contact, directly or indirectly, with one another as proof that
cancer is contagious. But scientists have found that these clusters
almost never reflect a greater incidence of cancer than would be found
in a random survey of the general public.
It is also impossible to be sure that environmental factors
and cultural factors such as diet and lifestyle are not responsible
when studying the causes of "clusters" of cancers. (To learn more about
this topic, see our document, Cancer Clusters.)
In most cases, the time between exposure to cancer-causing agents
(carcinogens) and the development of cancer is also unknown.
Still, because of the way cancer develops in the body, it can
be said with certainty that cancer is NOT spread from person to person.
People with cancer need to be around other
people.
Even today, families, friends, and co-workers of people with
cancer sometimes stay away when they learn about the disease. As a
result, people with cancer often say they feel isolated and alone. You
don't have to stay away from someone with cancer -- you cannot "catch"
it from them. Don't be afraid to visit a person with cancer. They need
your visits and support.
Additional resources
More information from your American Cancer
Society
We have selected some related information that may also be of
interest to you. These materials may be ordered from our toll-free
number, 1-800-ACS-2345 (1-800-227-2345).
- Environmental and Occupational Cancer Risk Factors:
Overview
National organizations and Web sites*
Along with your American Cancer Society, other sources of
patient information include:
Centers for
Disease Control and Prevention (CDC)
Toll-free number: 1-800-232-4636 (1-800-CDC-INFO
Web site: www.cdc.gov
National Cancer
Institute (NCI)
Toll-free number: 1-800-422-6237 (1-800-4-CANCER)
TTY: 1-800-332-8615
Web site: www.cancer.gov
*Inclusion on
this list does not imply endorsement by the American Cancer Society.
No matter who you are, we can help. Contact us anytime, day or
night, for information and support. Call us at 1-800-ACS-2345 (1-800-227-2345) or
visit www.cancer.org.
References
American Cancer Society. Cancers linked to infectious disease.
In: Cancer Facts
& Figures 2005. Atlanta, GA: American Cancer
Society; 2005.
Bonnet F, Lewden C, May T, Heripret L, et al.
Malignancy-related causes of death in human immunodeficiency
virus-infected patients in the era of highly active antiretroviral
therapy. Cancer.
2004;101:317-324.
Gansler T, Henley SJ, Stein K, Nehl EJ, Smigal C, Slaughter E.
Sociodemographic determinants of cancer treatment health literacy. Cancer.
2005:104:653-660.
Heath CW, Fontham ETH. Cancer etiology. In: Lenhard RE Jr,
Osteen RT, Gansler T, eds. Clinical
Oncology. Atlanta, GA: American Cancer Society; 2001:
39-54.
Hoshida Y, Aozasa K. Malignancies in organ transplant
recipients. Pathol Int.
2004 Sep;54(9):649-658.
Marcelin AG, Calvez V, Dussaix E. KSHV after an organ
transplant: Should we screen? Curr
Top Microbiol Immunol. 2007;312:245-262.
National Cancer Institute, Division of Cancer Epidemiology
& Genetics. Infections and Immunoepidemiology Branch. Accessed
February 11, 2009 at: http://dceg.cancer.gov/veb/research.
National Cancer Institute. U.S. National Institutes of Health.
What You Need To Know
About Cancer - An Overview. Accessed at
www.cancer.gov/cancertopics/wyntk/overview/page4 on February 11, 2009.
Last Medical Review: 02/23/2009
Last Revised: 02/23/2009
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