Re: Twenty five year follow-up for breast cancer incidence and mortality of the Canadian National Breast Screening Study: randomised screening trial
I have serious concerns about the quality of mammography in this study. As seen in Table 2, there was no relevant difference in mean tumor size (1.9 cm vs. 2.1 cm) and lymph node status (59.2% vs. 57.8% lymph node negative) between the mammography and control arms of this study. This indicates insufficient mammography technique and/or interpretation.
For comparison, recently published nationwide figures for the German mammography screening program show quite different figures: median tumor size decreased from 2.1 cm prior to screening to 1.4 cm with screening, while the fraction of lymph node negative cases increased from 57% to 78%.
Interestingly, Miller et al. did in fact find a significant breast-cancer specific mortality reduction in patients with non-palpable tumors, which are more similar to cases found in current quality-controlled screening programs. It is surprising that they did not comment on this.
For me, the most important question regarding this article is: how did it pass the peer review process at the BMJ?
Competing interests:
Affiliation with both a university hospital and a breast screening unit.
15 April 2014
Florian Engelken
Radiologist
Department of Radiology, Charité Universitätsmedizin Berlin, Germany
Rapid Response:
Re: Twenty five year follow-up for breast cancer incidence and mortality of the Canadian National Breast Screening Study: randomised screening trial
I have serious concerns about the quality of mammography in this study. As seen in Table 2, there was no relevant difference in mean tumor size (1.9 cm vs. 2.1 cm) and lymph node status (59.2% vs. 57.8% lymph node negative) between the mammography and control arms of this study. This indicates insufficient mammography technique and/or interpretation.
For comparison, recently published nationwide figures for the German mammography screening program show quite different figures: median tumor size decreased from 2.1 cm prior to screening to 1.4 cm with screening, while the fraction of lymph node negative cases increased from 57% to 78%.
Interestingly, Miller et al. did in fact find a significant breast-cancer specific mortality reduction in patients with non-palpable tumors, which are more similar to cases found in current quality-controlled screening programs. It is surprising that they did not comment on this.
For me, the most important question regarding this article is: how did it pass the peer review process at the BMJ?
Competing interests: Affiliation with both a university hospital and a breast screening unit.