Swedish researchers said that mammograms were able to detect non progressive breast cancer that would never have needed treatment. Some previous studies show that 54% of the mammograms detect such breast cancers but others say that the rate is about 1% only. But the present study is based on the direct observations.
Dr. Sophia Zackrisson, a radiologist from the Epidemiological Research Group, at Malmo University Hospital said that about 1 in 10 breast cancers detected by screening mammography are over-diagnosed meaning that in the absence of screening, the tumor would never have given any symptoms in its host.
Zackrisson said when compared to the number of lives saved by screening and other costs and benefits this level of over-diagnosis is lower. The study report was published in the British Medical Journal.
In the study, Zackrisson and her colleagues studied about 42,283 women between 45 and 69 years of age. During the trial, the researchers analyzed the rate of over-diagnosis of breast cancer. The women's health outcomes were tracked until December 2001, 15 years after the trial ended. They found that the rate of over-diagnosis of breast cancer was 10 percent in women screened when they were 55 to 69 years old, compared with women who were not screened.
Zackrisson said that one has to know more about the biologic characteristics of these tumors and doctors have to go on with the same treatment for all tumors.
Robert Smith, the director of cancer screening at the American Cancer Society said that the method used to determine the rate of over-diagnosis was faulty as it mixes women who were screened with those who did not undergo any screening.
Smith believes that women should definitely get regular mammograms as most breast cancers are life-threatening. He said that early detection of breast cancers especially if found before they spread to the lymph nodes are curable. Smith said that a small risk of being diagnosed with a non-progressive cancer is trivial to being diagnosed with a progressive cancer.
Smith said that the problem does not lie with the diagnosis part but with the over treatment.