Dr. H. Gilbert Welch, and his team from St. Charles Health System in Bend, Oregon, stated that close to one third of all women who are newly diagnosed with breast cancer are over-diagnosed and that screening is not having a great impact on the death rates seen in breast cancer cases.
Although fewer women are dying from the disease, the experts say this is not from screenings; it is due to the development of better medications and treatment therapies.
The new study looks at national data from 30 years and how rates have changed, or stayed the same, since mammograms were introduced. The researchers said, "It does not involve a select group of patients, a specific protocol, or a single point in time."
They wanted to determine whether mammography was working in regards to simple screening standards. In order to lower the incidence of deaths from breast cancer, two things are needed:
- Screenings need to be done before the cancer has become terminal.
- Screenings need to work to prevent fewer late stage cancers from developing, because every patient diagnosed using the first requisite is not found to have worse cancer later on.
The start of mammography screening in the U.S. has been linked to a two-fold increase in early detection of breast cancer each year; a total increase of 122 breast cancer cases per 100,000 patients. However, the rate of patients with late-stage breast cancer has decreased by 8%; a total reduction of 8 cases for every 100,000 patients.
The scientists believe that over 1.3 million women have been over-diagnosed with breast cancer in the last 30 years.
The researchers said:
"And although no one can say with certainty which women are overdiagnosed, there is certainty about what happens to them: they undergo surgery, radiation therapy, hormonal therapy for five years or more, chemotherapy, or (usually) a combination of these treatments for abnormalities that otherwise would not have caused illness."
The report notes that women aged at least forty years have a choice in the method of screening they use. Mammography benefit is lower than was previously believed in terms of reducing death rates.
"Women should recognize that our study does not answer the question 'Should I be screened for breast cancer. However, they can rest assured that the question has more than one right answer," concluded the researchers.