Gene link to inherited breast cancer offers future hope


Late last year, an international team of researchers forged a breakthrough in the fight against breast cancer, with its discovery of two genes -- BRCA1 and BRCA2 -- that are linked to an inherited form of breast and ovarian cancer.

Although for most cancer patients the news will have little direct significance, it is hoped that the discovery of the aberrant genes TC will lead scientists to genes that play a critical role in causing more common forms of the disease. Breast cancer kills 46,000 women each year in the United States alone.

Q: How many women suffer from inherited forms of breast cancer?

A: Only about 5 percent to 10 percent of breast cancers are the inherited form. Of these cases, BRCA1 and BRCA2 genes probably account for only half. The genes responsible for the other hereditary forms have not been discovered. Half the offspring of men and women who carry this gene will be susceptible to this hereditary form of the disease.

Q: What is the elevated risk for women with these genes?

A: The risk is significant. Researchers feel that women with BRCA1 and BRCA2 have about a 60 percent chance of developing breast cancer before age 50, and an 85 percent chance before age 65.

Q: What do researchers hope to accomplish with the discovery?

A: The isolation of these genes ultimately will allow early diagnosis of breast and ovarian cancer in women with a family history of the diseases. But understandably, some women question the advantage of early diagnosis for a disease they view as incurable. The long-term importance of the discovery is that it puts researchers a step closer to the development of new tools for improving prevention, detection, monitoring and treatment. For instance, early detection of tumors through mammography may be even more important for women carrying the gene.

Within two years, researchers hope to develop a blood test to identify women with the faulty genes.

The vast majority of breast-cancer cases (i.e., non-hereditary) are "sporadic" and strike women randomly. The cancers themselves appear the same, and treatment is more or less identical.

The discovery of the BRCA1 and BRCA2 genes could yield clues to their DNA code -- the body's hereditary blueprint. This could lead to a better understanding of both cancer types, their differences, and new strategies to prevent and treat them.

Dr. Matanoski is a physician and epidemiologist at the Johns Hopkins School of Hygiene and Public Health.

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