Having an abnormal breast cancer gene -- either BRCA1 (BReast CAncer gene 1) or BRCA2 (BReast CAncer gene 2) -- greatly increases a woman's lifetime risk of both breast cancer and ovarian cancer.
Still, a study has found that among women diagnosed with ovarian cancer, women with an abnormal BRCA1 or BRCA2 gene have a better prognosis than women without an abnormal BRCA1 or BRCA2 gene. The research was published in the Jan. 25, 2012 issue of the Journal of the American Medical Association.
Most inherited cases of breast cancer are associated with an abnormal BRCA1 or BRCA2 gene. Women with one of these abnormal genes:
- have up to an 85% lifetime risk of developing breast cancer
- have a much higher-than-average lifetime risk of ovarian cancer; estimates range from 15% to 60%
Researchers analyzed information from 26 studies involving 3,879 women diagnosed with ovarian cancer. About 30% of the women had an abnormal breast cancer gene:
- 909 (23%) had an abnormal BRCA1 gene
- 304 (8%) had an abnormal BRCA2 gene
- 2,666 (69%) had no abnormal breast cancer genes
The researchers compared 5-year survival rates -- the number of women alive 5 years after diagnosis -- in the three groups of women. Five-year survival rates were better in women with an abnormal breast cancer gene than in women without an abnormal breast cancer gene. Survival rates were:
- 44% in women with an abnormal BRCA1 gene
- 52% in women with an abnormal BRCA2 gene
- 36% in women with no abnormal breast cancer genes
It's not clear why having an abnormal breast cancer gene appears to improve ovarian cancer prognosis. The results are surprising because other research has suggested that ovarian cancer diagnosed in women with an abnormal breast cancer gene tends to be more aggressive compared to ovarian cancer diagnosed in women without an abnormal breast cancer gene.
The researchers believe that knowing if a woman diagnosed with ovarian cancer has an abnormal breast cancer gene could help plan treatment based on prognosis.
You can learn more about abnormal BRCA1 and BRCA2 genes and steps women with an abnormal gene can take to lower their risk on the Breastcancer.org Risk Factors: Genetics page.
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