Women who develop breast cancer before the age of 55 and carry the inherited gene which causes the disease are four times more likely to develop it in the other breast as well, a new study said Monday.
Only about five percent of breast cancer patients across all age groups have the inherited mutation of the breast cancer susceptibility genes known as BRCA1 or BRCA2.
But the study confirmed that the younger a woman is when she develops breast cancer, the more likely she has such a genetic mutation, said lead author Kathleen Malone, from the Fred Hutchinson Cancer Research Center in Seattle.
"In the youngest patients in our study -- those with a first cancer diagnosed before age 35 -- we found that 16 percent of those with one breast tumor and 54 percent of those who had developed two primary breast cancers carried a mutation," she said.
Carriers of either mutation who were diagnosed with breast cancer before age 55 faced an 18-percent likelihood of developing cancer in the opposite breast within 10 years as compared to a five-percent probability among women who were mutation-free, according to the study published in Monday's edition of the Journal of Clinical Oncology.
"These elevated mutation frequencies and risks for contralateral breast cancer associated with these mutations underscore the need for women diagnosed with a first breast cancer at a young age -- regardless of family history -- to consider genetic testing and to discuss it with their health care providers," Malone said.
"If they are found to carry a mutation in either of the BRCA genes, they should consider strategies for treatment, prevention and heightened surveillance in relation to their increased risk of a subsequent breast cancer diagnosis."
The study, coordinated by Memorial Sloan Kettering Cancer Center, analyzed findings from 705 women with contralateral breast cancer and a comparison group of 1,398 women with unilateral breast cancer. All of the women had been first diagnosed before age 55.
And none of the participants had evidence of cancer spread beyond the lymph nodes upon diagnosis, the study said.
More than 180,000 American women are diagnosed with breast cancer annually.