June 30th, 2011
A new study of more than 133,000 women confirms that regular mammography screenings reduce a woman’s risk of dying from breast cancer.
The Swedish Two-County Trial study began in the late 1970s. In its first phase, researchers divided the study participants in to two groups: Women who were given regular mammograms, and women who were treated with “usual care,” or treatment that did not include mammograms. That screening period lasted for seven years, after which the study’s second phase began and the women were followed for an additional 29 years.
“We estimated about 1,300 mammograms need to be done to save one life,” explains Robert A. Smith, Ph.D., director of Cancer Screening at the American Cancer Society and one of the study’s authors.
To put that number another way, Smith and his fellow authors estimate that screening 300 women every two to three years for 10 years total prevents one death from breast cancer. Among the study participants, Smith calculates that 42 years of life were saved for every 1,000 women who were invited to have a regular mammogram during the study’s screening period.
Yet despite studies like Smith’s, who should get a mammogram and how often can be confusing questions. The American Cancer Society advises women to begin annual mammogram screenings at age 40.
“Women should think of mammography as a kind of insurance against getting a diagnosis with a breast cancer that will be harder to treat and may actually become uncurable,” says Smith.
“It’s not a perfect examination by any means but we have quite an accumulation of data that shows mammography is associated with a reduced risk of dying from breast cancer and the opportunity to be treated less aggressively.”
But the United States Preventive Services Task Force says the decision to get a mammogram at the age of 40 is an individual choice that women should make with their doctors. Otherwise, the Task Force recommends women wait to begin regular mammography screening at the age of 50 and even then advises that mammograms are only needed once every two years.
In a statement to CNN, Dr. Virginia A. Moyer, chair of the task force, said these latest findings would probably not change the panel’s guidance.
“Overall, this study adds depth to our knowledge of the potential adverse effects of radiation exposure for mammography, but is not different from the estimates used in the 2009 recommendation, so would not be expected to significantly impact the debate.”