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Untitled Document
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| Breast
and Ovarian Cancer |
| Hereditary Syndromes Can Cause Breast and Ovarian Cancer |
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By
Kari Danziger,
MS, CGC
Reviewed
By Beth Crawford,
MS, CGC
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Mutations
in the cancer
susceptibility genes
BRCA1 and BRCA2
are responsible for up to 70 percent of hereditary breast
cancers and a significant number of hereditary ovarian
cancers. However, additional genes and cancer syndromes
play a role in some hereditary breast and ovarian cancers.
Clues from your family
medical history can help determine whether any of
these other genetic factors are involved in your family's
hereditary breast or ovarian cancer.
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Ovarian Cancer in Hereditary Nonpolyposis Colorectal
Cancer Syndrome
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| HNPCC
syndrome puts women at almost four times greater
risk for developing ovarian cancer than women in
the general population. |
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Hereditary
nonpolyposis colorectal cancer (HNPCC, also known
as Lynch Syndrome), is a rare hereditary colon cancer
syndrome that is responsible for approximately 2.5 percent
of colon cancer cases. It als confers an increased risk
for a number of other types of cancers, including ovarian
cancer. HNPCC is caused by a mutation
in one of several mismatch repair
genes — which repair mistakes that occur in the DNA
copying process during cell
division. This syndrome puts women at almost four
times greater risk for developing ovarian cancer than
women in the general population. Characteristics of HNPCC
include colon polyps,
early-onset colon and endometrial (uterine) cancers, and
additional cancers including small intestine, ureter,
and stomach. |
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Breast
Cancer in Li-Fraumeni Syndrome
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| Overall,
less than one percent of all breast cancers are
associated with Li-Fraumeni syndrome. |
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Li-Fraumeni
syndrome is a rare, hereditary cancer syndrome that predisposes
people to develop early-onset breast cancer and soft tissue
tumors called sarcomas, in addition to other early-onset
cancers. Overall, less than one percent of all breast
cancers are associated with Li-Fraumeni syndrome.
Li-Fraumeni
syndrome is linked to an inherited mutation in a gene
called p53, which, when functioning properly, prevents
cells with DNA damage from copying themselves. Breast
cancers in Li-Fraumeni families typically occur between
the ages of 15 and 44. In fact, it is estimated that
50 percent to 80 percent of women who have inherited
mutations in the p53 gene develop breast cancer by the
age of 45.
People
with Li-Fraumeni syndrome are at risk for developing
other cancers, including leukemia, and tumors of the
adrenal glands, bones, brain, lung, pancreas, and skin.
These cancers are often diagnosed in childhood. The
risk of developing any of the additional tumors associated
with Li-Fraumeni syndrome is 50 percent by age 30 and
90 percent by age 70. An unusual feature of this syndrome
is that about 50 percent of people who develop cancer
in one tissue also develop a second or new primary
cancer.
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Breast
Cancer and the Ataxia-Telangiectasia Gene
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Ataxia-telangiectasia
is a rare genetic disorder that causes neurological
problems and immune system abnormalities. It is associated
with an increased risk for certain types of cancers,
particularly leukemias and lymphomas, which are cancers
of the immune system.
This
condition is inherited in a recessive
pattern, which means that an individual has to inherit
two mutated copies of the ataxia-telangiectasia gene
(AT gene) — one from each parent — in order
to develop the disease. If a person inherits only one
mutated copy of the AT gene they are carriers
for the disease; they do not develop ataxia-telangiectasia,
but they can pass the mutated gene on to their children.
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| Some
researchers think that women who are carriers for
the AT gene are at a higher risk for developing
breast cancer. |
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Approximately one percent of the population carry a mutated AT gene. Some researchers think that women who are carriers for the AT gene are at a higher risk for developing breast cancer. However, not all studies have found a link between mutations in the AT gene and breast cancer. (For recent news about AT and breast cancer, see Related News below.) |
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Breast
Cancer in Cowden Syndrome
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Early
breast cancer and thyroid disease (both cancerous and
noncancerous) are characteristics of Cowden syndrome,
a rare hereditary cancer syndrome linked to inherited
alterations in a gene called PTEN. Other hallmarks of
Cowden syndrome include specific skin and mouth lesions,
gastrointestinal lesions (growths in the lower digestive
tract), and possible tumors or malformation of the genital
and urinary tracts (such as uterine fibroids).
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| Women
who have inherited Cowden Syndrome have a 25 percent
to 50 percent chance of developing breast cancer
during their lifetimes. |
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Researchers
estimate that women who have inherited this condition
have a 25 percent to 50 percent chance of developing breast
cancer during their lifetimes — typically in their
late 30s or early 40s, and possibly in both breasts.
People
with Cowden Syndrome also have a three percent to seven
percent risk of developing thyroid cancer, and 40 percent
to 60 percent of people have thyroid nodules and goiters.
It is currently unclear what percent of breast cancer
cases are caused by Cowden syndrome.
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More
on Cowden Syndrome (Coming soon)
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References
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Watson,
P. and Lynch, H.T. (1993). Extracolonic cancer in hereditary
nonpolyposis colorectal cancer. Cancer. 71(3):677-85.
Li,
F.P. and Fraumeni, J.F. Jr. (1969). Soft-tissue sarcomas,
breast cancer, and other neoplasms. A familial syndrome?
Ann Intern Med. 71(4):747-52.
Li,
F.P. et al. (1988). A cancer family syndrome in twenty-four
kindreds. Cancer Res. 48(18):5358-62.
Lustbader,
E.D. et al. (1992). Segregation analysis of cancer in
families of childhood soft-tissue- sarcoma patients.
Am J Hum Genet. 51(2):344-56.
Ataxia-Telangiectasia:
Swift,
M. et al. (1991). Incidence of cancer in 161 families
affected by ataxia-telangiectasia. N Engl J Med.
325(26):1831-6.
FitzGerald, M.G. et al. (1997). Heterozygous ATM mutations
do not contribute to early onset of breast cancer. Nat
Genet. 15(3):307-10.
Cowden
Syndrome:
Nelen, M.R. et al. (1996).
Localization of the gene for Cowden disease to chromosome
10q22-23. Nat Genet. 13(1):114-6.
Starink, T.M. et al. (1986). The Cowden syndrome: a
clinical and genetic study in 21 patients. Clin Genet.
29(3):222-33.
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