The American Cancer Society is recommending annual MRIs as well as mammograms for women whose close relatives have had breast cancer - part of new guidelines that could affect as many as 1.4 million women.
The recommendation, prompted by advice from an expert panel, even includes some women whose aunts and grandmothers have had the disease - in addition to those with mothers and sisters who had breast cancer.
It is the first time the Cancer Society has urged the use of magnetic resonance imaging (MRI) - which detects the tiniest tumors - for breast-cancer screening, in addition to mammograms.
"One truth about breast cancer is that when it's detected early, we can cure it," said Dr. Connie Lehman, director of breast imaging at the Seattle Cancer Care Alliance and a member of the expert panel.
In 2003, the Cancer Society issued guidelines that stopped short of recommending MRIs for women at high risk for the disease. More research evidence on MRI effectiveness now warrants it, the society said.
The new recommendations could have large implications for medical insurers because they use such guidelines, along with scientific studies, in deciding whether to cover certain diagnostic procedures and treatments.
MRIs use magnetic fields to detect tumors, while mammography uses X-rays. The costs vary, but MRIs generally are much more expensive: $1,000 or more, compared with about $100 to $150 for mammograms.