Journal of General Practice

How do Breast Cancer Mortality Rates Differ between Women who are Screened Annually and Biennially by Mammography?

Abstract

Amir Hossein Mortazavi Entesab

Context: Breast cancer is the most common non-skin cancer and second deadliest cancer in women. Mammography, an X-ray of the breast, serves as the primary diagnostic tool for breast cancer detection as it reduces the risk of death through early detection and treatment of the disease. The medical community, however, has not agreed on how frequently such screenings should be performed [1]. Various organizations have produced different guidelines regarding the suggested frequency of routine mammograms. For example, the United States Preventive Services Task Force (USPST) endorses biennial mammography screenings for females ages 50-74, whereas the American Cancer Society (ACS) advocates annual mammography screenings for women beginning at age 40. It is this review’s hypothesis that annual mammography is proving to be statistically more beneficial than biennial screening in the reduction of breast cancer mortality rate. Methods: Full text articles from the U.S. National Institute of Health’s Public Medicine’s archives (PubMed) were reviewed in order to compare annual versus biennial mammographic screenings and the diagnostic advantages, detriments and mortality rates of each interval. Results: The majority of articles agree that women between the ages of 40-49 years undergoing biennial screenings are more likely to be diagnosed with late stage disease than women diagnosed during annual screenings. The results for women 50 years and older are less conclusive. While some studies of the over-50 group delineate no difference in the incidence of late-stage disease using either the biennial or annual intervals, the majority of findings suggest the annual interval is more effective than the biennial screening in detecting early stage cancer. Conclusion: Overall, women partaking in annual mammography screening experience decreased false positive “recall” rates. In addition, earlier diagnoses through annual screenings help detect smaller tumors providing a more hopeful prognosis. While these findings support the importance of annual mammography screenings for women 40 years and older, studies indicate that annual screenings only minimally improve estimated breast cancer survival rates for women aged 50-74 years compared to biennial screening.