Breast-Cancer Genes Pose Lower Risk Than Thought: Study

Contrary to popular beliefs, the risk posed by certain gene mutations linked to breast cancer may be lower than commonly believed, a new study shows.

Earlier it was believed that carriers of either of the gene mutations BRCA1 and BRCA2 were at an 80 percent increased risk of suffering from breast cancer.

However, researchers at the Memorial Sloan-Kettering Cancer Center in New York have found that a carrier’s risk of developing breast cancer by age 70 ranges between 36 percent and 52 percent.

The study led by Dr. Colin Begg studied around 2,000 women diagnosed with breast cancer before the age of 55. Of it around1400 women were diagnosed with cancer in one breast and around 700 women had cancer tumors in both breasts. Information on whether patients’ close relatives also had been diagnosed with cancer was also collected.

The researchers reported that 5 percent of those with cancer in one breast had a BRCA1 or BRCA2 mutation and 15 percent of those with cancer in both breasts carried risky genes.

Furthermore, the risk was highest among the relatives of the women who were diagnosed at a young age. The researchers noted that if a woman with a BRCA mutation was diagnosed at age 35 or younger her first-degree relatives had a 52 percent chance of having been diagnosed with breast cancer by age 70 and 95 percent by age 80 years.

However on the other hand, if a woman with a BRCA mutation was diagnosed at age 45 or older, her relatives had a 36 percent likelihood of breast cancer by age 70 and 44 percent by age 80 years.

Additionally, if a woman was diagnosed with cancer in both breasts, her relatives faced a markedly higher risk for the disease, in spite of the age of diagnoses, the study showed.

The results of the study that was sponsored by the National Cancer Institute feature in today’s edition of the Journal of the American Medical Association.