Study: Mammograms Do Not Impact Breast Cancer Death Rate of Women in 40s

Mammograms do not appear to significantly decrease the death rate from breast cancer in women ages 40 to 49 based on 11 to 16 years of follow-up, according to the Canadian National Breast Screening Study.

Prior study results had shown that seven to ten years after the first screening visit, screening had not reduced breast cancer deaths. However, some experts believe that it takes longer than ten years to show screening benefits.

Researchers looked at mammograms and breast examinations of 50,430 women who had no prior history of breast cancer and had not had a mammogram for at least one year before entering the study.

The women were enrolled between 1980 and 1985 and were assigned to have both yearly mammograms and breast examinations for the next five years or to receive usual care. Usual care consisted of mammograms and breast exams performed only if the patient's doctor suggested them. Women in both groups were given instruction on examining their own breasts. Researchers compared the frequency of death due to breast cancer in the women in the mammogram group compared to the frequency of death in the usual care group over an average follow-up period of 13 years.

A total of 105 of the 25,214 women in the mammogram group and 108 of the 25,216 women in the usual care group died of breast cancer. The incidences of cancer that had spread and cancer that had not spread were about the same in both groups, according to the study published in the Annals of Internal Medicine.

"After 11 to 16 years of follow-up, four or five annual screenings with mammography, breast physical examination, and breast self-examination had not reduced breast cancer mortality compared with usual community care after a single breast physical examination and instruction on breast self-examination," concluded the researchers.

Other sources: Annals of Internal Medicine