Had the 1986 Forrest Report – which led to widespread mammography screening in Great Britain – included the harms of screening for breast cancer, it might never have become standard practice, according to a new British Medical Journal report. The American College of Radiology (ACR) promptly criticized the report as flawed, being based on “discredited and obsolete data.”
James Raftery, PhD, and Maria Chorozoglou of Wessex University considered the studies used as the basis for the Forrest Report, adding harms associated with mammography-driven biopsies and other effects into a life-table model based on data from systematic reviews, trials, and other models. The work was sparked by their desire to flesh out the contentions of a 2009 Gotzsche and Nielsen Cochrane Review article concluding that it was “not clear whether screening does more good than harm.”
The American College of Obstetricians and Gynecologists, the National Comprehensive Cancer network, the American College of Radiology, and the American Cancer Society all back annual screening for women ages 40 and older; the National Cancer Institute recommends screening biannually starting at age 40; and the U.S. Preventive Services Task Force, recommends biannual screens starting at age 50. Several studie have found mammography to cut breast cancer mortality around 25 percent.
The researchers considered women aged 50 and over who were invited for breast cancer screening. Including harms reduced the estimate of net cumulative quality-adjusted life years (QALYs) gained after 20 years from 3,301 to 1,536 – or by more than half.
The ACR asserts that Raferty and Chorozoglou’s data underestimate the lives saves by mammography screening by half.
“The bottom line is that we know that discontinuing regular mammograms will result in thousands more breast cancer deaths each year. That human cost would be too high,” said Barbara Monsees, MD, chair of the American College of Radiology Breast Imaging Commission.
The best estimates from the Cochrane review generated negative QALYs for the first seven years of screening, 70 QALYs after 10 years, and 834 QALYs after 20 years, Raferty and Chorozoglou wrote.
“This analysis supports the claim that the introduction of breast cancer screening might have caused net harm for up to 10 years after the start of screening,” they concluded.
