Adapted from the NCI Cancer Bulletin.
Results from a study to be published in the July 20, 2007, Journal of Clinical Oncology showed that each successive annual mammogram lowered a woman's breast cancer mortality risk by about 31 percent. Compounding this benefit over a period of four years would cut a woman’s cumulative risk of breast cancer death by 88 percent. (See the journal abstract.)
Dr. Timothy L. Lash of Boston University was the lead author of the cohort study, which identified 1,846 breast cancer patients from six Cancer Research Network (CRN) sites chosen to maximize ethnic and geographic diversity.
All women were diagnosed with stage I or II breast cancer between 1990 and 1994, and were designated as "survivors" for the purposes of the study 90 days after finishing their initial breast cancer treatment. The 178 women who died of breast cancer within five years were closely matched to 634 control subjects who were followed at least as long as the women who died. Protective effects of annual mammography were found to be the strongest among women with stage I disease, those who had received mastectomy, and those older than 79.
In an editorial, Dr. Jeanne Mandelblatt from the Lombardi Comprehensive Cancer Center in Washington, DC, commended "this high-quality observational research" that emerged from CRN, a National Cancer Institute-funded collaboration between 12 large managed care systems. The large cohort study provides the best data likely to be developed on this question, because a clinical trial that randomized women to "no mammography" would disregard current guidelines, which recommend that survivors receive annual surveillance mammograms.