The possibility of discovering the genetic predisposition of cancer presents a double-edged sword: of fear and hope. When so many women - 192,000 in America - are diagnosed with breast cancer, exploring the hereditary basis of cancer may reveal information that can save a patient's life. Approximately 5 to 10 percent of these women have a hereditary form of the disease. Alterations in the genes called BRCA1 and BRCA2 (short for breast cancer 1 and breast cancer 2) are involved in many such cases.

One Israeli family's genetic history is illustrative. Mrs. L. was married with three healthy daughters. She had been diagnosed with breast cancer at age 41 and had to undergo a breast resection. Thirteen years later at the age of 54 she was found to have non-Hodgkin's lymphoma and had to undergo radiation treatment. This onset triggered an investigation into the family's cancer history. It turned out that Mrs. L.'s grandmother had colon cancer at age 49 and lung cancer at age 65; a sister had lung cancer at age 70; a niece had breast cancer at age 60; and her daughter had breast cancer at age 39. Her father had pancreatic cancer at age 62 and a paternal aunt had breast cancer in her 50's. This aunt's daughter had breast cancer at age 60, and her brother died of a brain tumor.

Rabin Medical Center suggested genetic testing. The results were informative. Mrs. L. was found to carry a 185delAG mutation in the BRCA1 gene. This mutation confers a 50-80% risk for breast cancer, increased risk for contralateral breast cancer, and a 40% risk for ovarian cancer. The consequences of carrying this mutation meant that each of Mrs. L's children would have a 50% risk of inheriting the mutation and therefore were at risk for inherited breast and ovarian cancer.

All three of Mrs. L's daughters came to Rabin Medical Center for genetic counseling and then decided to undergo genetic testing. Her 24-year-old daughter was found negative for the family mutation and was at normal population risk for breast/ovarian cancer. Her 28-year-old daughter was also found to be healthy and not to carry the family mutation. Mrs. L's 31- year-old, otherwise healthy and pregnant at the time of counseling, was found to carry the family mutation and therefore at increased risk. The hospital recommended that she undergo routine surveillance, including self breast examinations every month, clinical exams every six months, and breast imaging once a year.

During counseling, many complex issues arose. At what age is it appropriate to undergo genetic testing? If a daughter is pregnant, would the results of her mother's testing cause the daughter undo stress? What are the true benefits of genetic testing for young women prior to family planning? While there are no definite answers to these questions, in the majority of cases, the benefits of foreknowledge can be truly life saving. Genetic testing can offer many avenues of prevention and early detection. This is the gift of genetics.