New Study Calls for Change In Deciding Frequency of Mammograms

Mammograms should not be done on a one-size fits all basis, but instead should be personalized based on a woman’s age, the density of her breasts, her family history of breast cancer and a number of other factors including her own values. That’s the conclusion of a new study in the July 5 issue of the Annals of Internal Medicine.

The study is likely to be controversial as it challenges the current guidelines from groups such as the American Cancer Society and the US Preventive Task Force which recommend one frequency – screening every 1 or 2 years – for all women.

No one doubts that mammograms save lives but there is disagreement over when women should begin getting mammograms and how often they should get them: should they be done every two years starting at 50 or every year starting at age 40?

“Most guidelines use age as the determining factor in when, and how often, a woman should get a mammogram,” says Steve Cummings, MD, of the San Francisco Coordinating Center at the California Pacific Medical Center Research Institute – part of the Sutter Health network - and the lead author of the study. “What our study shows is that other factors, particularly breast density, are just as important, if not more so, in helping a woman decide what is most appropriate for her. We show that mammography should be personalized. The best interval for you depends on your age, breast density, and other risk factors for breast cancer.”

Many studies have shown that the denser a woman’s breast on a mammogram, the greater her risk of breast cancer. Low density or fatty breasts means a low risk of breast cancer while high density or less fatty breasts means a higher risk.

Using data from the Breast Cancer Surveillance Consortium and Surveillance Epidemiology and End Results of the National Cancer Institute. The researchers developed a model to compare the lifetime costs and health benefits for women who got mammograms every year, every two years, every three to four years, or who never got a mammogram. The women all had different risk factors for breast cancer and the model assumed that they all began as healthy but could subsequently fall into one of six different categories: remain healthy, develop ductal carcinoma in situ (DCIS), develop localized invasive breast cancer, regional invasive breast cancer, distant invasive breast cancer, die from invasive breast cancer, or die from causes other than breast cancer.

The authors used the data to estimate how many extra mammograms over 10 years would be needed to prevent one death from breast cancer in those having mammograms once every three to four years compared to no mammograms, and in those having mammography every two years compared to once every three to four years. They also estimated the costs for each frequency of mammography for each year of quality life gained.

“Our analysis suggests that women with a first-degree relative with breast cancer or with a history of a breast biopsy should have an initial screening mammography at age 40,’’ said study co-author Karla Kerlikowske, MD, MS, an expert in mammography at the University of California, San Francisco.