In this limited space I cannot possibly address all the errors in the Bleyer analysis so I will concentrate on the fundamental issue.
In his paper with Dr. Welch, in the prestigious New England Journal of Medicine (NEJM) , Dr. Bleyer sought to use Surveillance, Epidemiology, and End Results (SEER) data to show that there is massive overdiagnosis of breast cancer because of mammography screening. Their fundamental claim was that, in 2008 alone, there were more than 70,000 cases of breast cancer that would have disappeared on their own had they not been detected by screening (78,000 as he now claims in 2011). In fact, there is not a single credible report of an invasive cancer disappearing on its own. One would think that if there were 70,000 cases of disappearing breast cancer in a single year, someone would have published a credible report.
As Dr. Bleyer has, subsequently, written in response to my review of their analysis and my concerns , they actually had no data to permit them to, scientifically, blame anything on screening because they had no data on who had mammograms and they had no data on which cancers were detected by mammography. Despite this fundamental fact, Bleyer and Welch’s analysis is being used by guidelines panels to reduce access to screening.
Their paper was based on (as Dr. Bleyer has written) their “best guess” as to what the incidence of breast cancer would have been in 2008 (now up to 2011) had there not been any screening (which began in the mid-1980s). The authors chose to ignore 40 years of data from the Connecticut Tumor Registry (CTR), which has been used by every other author that I have been able to find who has evaluated breast cancer incidence prior to SEER. The CTR showed that the incidence of invasive cancers had been increasing by at least 1% per year dating back to at least 1940 . As I wrote in rebuttal to their paper , had they used the data-backed rate of increase and not their guess, there was no evidence of any “overdiagnosis” of invasive breast cancer. In fact, there were fewer invasive cancers than would have been expected.
In this latest analysis by Dr. Bleyer, he confirms my analysis as well as that by Helvie et al. (which he incorrectly disparaged). It is all there in his figure 4. I will go through it step by step.
In their analysis, Bleyer and Welch did what no expert in breast cancer would do. They combined the Ductal Carcinoma in Situ (DCIS) data with small invasive cancers and called them “early-stage cancer.” Virtually everyone agrees that DCIS lesions are a major conundrum, but this is nothing new . There have been numerous efforts over the past decades to try to better tailor therapy for DCIS lesions knowing that some, but not all, will progress to invasive cancers. If Bleyer and Welch had written that we need better management of DCIS, the paper would not have been published because this is very old news.
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References
1. Bleyer A., Welch H.G.: Effect of three decades of screening mammography on breast-cancer incidence. N Engl J Med 2012; 367: pp. 1998-2005.
2. Bleyer A.: Were our estimates of overdiagnosis with mammography screening in the United States “based on faulty science?”. Oncologist 2014; 19: pp. 113-126.
3. Kopans D.B.: Arguments against mammography screening continue to be based on faulty science. Oncologist 2014; 19: pp. 107-112.
4. Garfinkel L., Boring C.C., Heath C.W.: Changing trends. An overview of breast cancer incidence and mortality. Cancer 1994; 74: pp. 222-227.
5. Ernster V.L., Barclay J., Kerliikowske K., et. al.: Incidence of and treatment for ductal carcinoma in situ of the breast. JAMA 1996; 275: pp. 913-918.
6. Helvie M.A., Chang J.T., Hendrick R.E., et. al.: Reduction in late-stage breast cancer incidence in the mammography era: implications for overdiagnosis of invasive cancer. Cancer 2014; 120: pp. 2649-2656.
7. Etzioni R., Xia J., Hubbard R., et. al.: A reality check for overdiagnosis estimates associated with breast cancer screening. J Natl Cancer Inst 2014; 106: pp. dju315.