Women, particularly those in their middle age, are recommended to have regular mammogram as this could help them detect early signs of breast cancer. The Centers for Disease Control and Prevention (CDC) has, in fact, recommended that women who are 50- to 74 years old have mammogram every other year. A new study, however, has cast doubts on the perceived value and benefits of mammography.
In the study published in the British Medical Journal (BMJ) Feb. 11, researchers in Canada evaluated the value of mammography screening by involving 90,000 women who were between the ages 40 and 59 over a 25-year period. Half of the women had yearly mammograms and physical breast examinations for five years while the other half received only physical examinations.
The researchers found that the rate of women dying of breast cancer is the same whether or not they underwent annual mammogram. They also found that 22 percent of the breast cancers detected by mammogram were over-diagnosed, which means that the tumors that the mammograms revealed were not actually a threat and did not require surgery, chemotherapy or radiation.
"Annual mammography in women aged 40-59 does not reduce mortality from breast cancer beyond that of physical examination or usual care when adjuvant therapy for breast cancer is freely available," the researchers wrote. "Overall, 22% (106/484) of screen detected invasive breast cancers were over-diagnosed, representing one over-diagnosed breast cancer for every 424 women who received mammography screening in the trial."
Study researcher Anthony Miller, professor emeritus at the University of Toronto, said that although majority of breast cancers can be detected by mammography, there are doubts on the value of breast screening in reducing deaths from breast cancer.
"The majority of breast cancers are detectable by mammography, but whether or not this is beneficial has now become very controversial," Miller said. "If you're able to cure cancers by treatment, no matter what stage they're at, there isn't any role for screening. So as the treatment improves, the contribution of screening gets less and less."
Mette Kalager, a breast cancer surgeon and researcher at the University of Oslo in Norway, wrote in an accompanying editorial that the result of the study does not support screening women below the age of 60. Nonetheless, she said that changing policies may be difficult because research funders, governments and doctors may have vested interests.
"As time goes by we do indeed need more efficient mechanisms to reconsider priorities and recommendations for mammography screening and other medical interventions," Kalager and her colleagues wrote in the editorial. "This is not an easy task, because governments, research funders, scientists, and medical practitioners may have vested interests in continuing activities that are well established."
