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Gene mutation carries increased cancer risks
NEW YORK, Aug 03 (Reuters Health) -- Mutations in the BRCA2 gene -- a gene known to be related to breast and ovarian cancers -- appear to increase the risk of several different cancers.
The British Cancer Linkage Consortium studied 173 families with BRCA2 mutations from 20 medical centers throughout Europe and North America, comparing the families' cancer rates with those of the general population, according to Dr. Douglas Easton from Strangeways Research Laboratory in Cambridge, UK.
Based on complex formulas that took local population-specific cancer rates into account, the researchers found significant increases in the occurrence of five cancers (besides breast and ovary):
-- 3.5-fold increase in cancer of the pancreas,
-- 2.6-fold increase in cancer of the stomach,
-- 5-fold increase in gallbladder and bile duct cancer,
-- 2.6-fold increase in malignant melanoma (skin cancer), and
-- 4.7-fold increase in prostate cancer.
These higher rates of cancers unrelated to cancer of the breast and ovary markedly increased the overall risk of acquiring cancer during the lifetime of BRCA2 gene mutation carriers, according to the report in the August 4th issue of the Journal of the National Cancer Institute.
Including breast and ovarian cancers, the researchers report, "the estimated cumulative risks for all cancers in women would be 32% by age 50 years, 56% by age 60 years, and 90% by age 70 years."
Similarly, the authors write, "the cumulative risk for all cancers in men would be 4% by age 50 years, 13% by age 60 years, and 32% by age 70 years."
The study also confirmed earlier reports of increased breast and ovarian cancer in women carrying mutated BRCA2 genes. "The estimated cumulative risks (for breast cancer)," the report indicates, "are then 60% by age 50 years, and 77% by age 70 years. The corresponding estimated cumulative risks of ovarian cancer were 3.3% by age 50 years and 15.9% by age 70 years."
"This more general increase in cancer risk appears to contrast with the situation for BRCA1, where no excess risk was observed except for prostate cancer and (cancer of the colon and rectum)," the authors observe.
The research team concludes that the presence of BRCA2 gene mutations should call for increased vigilance in those patients. Though early detection of such uniformly fatal diseases as cancer of the pancreas may not affect mortality, they write, screening for treatable conditions -- including prostate cancer and breast cancer -- might be justified at substantially younger ages.
SOURCE: Journal of the National Cancer Institute 1999;91:1310-1316.
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