A new study published on Thanksgiving in The New England Journal of Medicine has been widely headlined as questioning whether widespread use of mammograms really saves as many lives as advocates claim, more than 230,000 women a year.
The short take from researchers at Dartmouth College and Oregon Health Sciences University is that 30 years of screenings has resulted in some 1.3 million women being diagnosed with cancer for small breast lesions that actually would have been harmless. At the same time, while the number of early-stage cancers doubled in three decades – from 112 to 234 cases per 100,000 women – the detection rate of late-stage breast cancer fell just 8 percent – from 102 to 94 cases per 100,000 women.
Of course, the findings were quickly assailed by legions of health professionals who have fought to make mammography a standard preventive health service and who continue trying to get more women, minorities in particular, to utilize the services. Each year, about 230,000 American women are diagnosed with invasive breast cancer out of some 39 million who get mammograms, at a cost of $5 billion.
The report’s strongest criticism is less about too much screening and more about too little understanding of the risk posed by small malignancies found earlier and earlier – and about clinicians who approach all tumors the same way.
“Our ability to detect things is far ahead of our wisdom of knowing what they really mean,” co-author Dr. H. Gilbert Welch, a Dartmouth professor of epidemiology and biostatistics, told one interviewer. The study’s main point is not to discourage women from being screened, but to make them more aware of the test’s shortcomings.
Right now, the American Cancer Society urges mammograms for all women every year starting in their 40s; the U.S. Preventive Services Task Force recommends women get screened every other year starting in their 50s.
Casting a wide net is clearly finding more tumors, but not many more late-stage tumors. Welch said rather than screening based on age, mammography should be done based on risk from factors such as family history or genetics.
And, just as men facing highly sensitive but less-than-certain prostate-cancer tests have learned in the past few years, women with an early positive breast exam need to be empowered to consider alternatives to aggressive treatment based on their own risk factors. Prevention is only as good as the advice and care that follows the screening.