(HealthDay News) — Mammographic breast cancer screening may initially cause more harm than good when including the effects of harms in the analysis, according to a study published online December 8 in BMJ.
James Raftery, PhD, and Maria Chorozoglou, from the University of Southampton in the United Kingdom, and colleagues investigated whether mammographic breast cancer screening could be doing more harm than good, as was claimed in a Cochrane review. The Forrest report, which led to the introduction of screening in the United Kingdom, was updated by the researchers by developing a life table model, and extending it using data from relevant current literature. Participants included women aged 50 years and older, who were invited for breast cancer screening. The main outcome measure was quality-adjusted life years (QALYs), which combine the reductions in quality of life due to false positive diagnoses and surgery with the life years gained from screening.
The investigators found that by including the effects of harms, the updated estimate of net cumulative QALYs gained after 20 years was reduced by more than half, from 3,301 to 1,536. For the first seven years of screening, the Cochrane review’s best estimates generated negative QALYs, whereas the values were 70 and 834 QALYs after 10 and 20 years, respectively. These results were shown to be robust to a range of assumptions in sensitivity analyses, especially up to 10 years. The importance of the level and duration of harms from surgery was also indicated.
“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,” the authors write.