WASHINGTON, March 28 (Xinhua) -- Certain women with an especially high risk of developing breast cancer should get magnetic resonance imaging (MRI) scans along with their yearly mammogram, according to a new American Cancer Society guideline pulished on Wednesday.

    The new guideline recommends MRI screening in addition to mammograms for women who meet at least one of the following conditions: they have a BRCA1 or BRCA2 mutation; they have a first-degree relative (parent, sibling, child) with a BRCA1 or BRCA2 mutation, even if they have yet to be tested themselves; their lifetime risk of breast cancer has been scored at 20 percent-25 percent or greater, based on one of several accepted risk assessment tools that look at family history and other factors; they had radiation to the chest between the ages of 10 and 30; they have Li-Fraumeni syndrome, Cowden syndrome, or Bannayan-Riley-Ruvalcaba syndrome, or may have one of these syndromes based on a history in a first-degree relative.

    The two tests together give doctors a better chance of finding breast cancer early in these women, when it is easier to treat and the chance of survival is greatest, ACS said in the guideline.

    MRI scans are more sensitive than mammograms, but they are also more likely to show spots in the breast that may or may not be cancer. Often there is no way of knowing whether or not these spots are cancerous short of a follow-up biopsy or some other invasive procedure. That is why the test is not recommended for women with an average risk of breast cancer, the guideline says.

    "As with other cancer screening tests, MRI is not perfect and in fact leads to many more false-positive results than mammography," explains Christy Russell, chair of the ACS Breast Cancer Advisory Group and co-author of the new guideline. "Those false-positives, which can lead to a high number of avoidable biopsies, can create fear, anxiety, and adverse health effects, making it imperative to carefully select those women who should be screened using this technology."

    For women at average risk, ACS recommends getting annual mammograms and breast exams by a physician, beginning at age 40. Most high-risk women should begin getting MRIs and mammograms at age 30, the new guideline says.