Nagtegaal ID, Allgood PC, Duffy SW et al.
Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands.
Cancer 2011;117:1360–8.
[2] Explaining the difference in prognosis between screen-detected and symptomatic breast cancers.
Allgood PC, Duffy SW, Kearins O et al.
Wolfson Institute for Preventive Medicine, London, UK.
Br J Cancer 2011;104:1680–5.
Editor’s note: Since the introduction of breast cancer screening programs, a decrease in breast cancer-related mortality has been accompanied by an increase in the incidence of breast cancer, particularly early stage disease. While it is clear that breast cancers detected by screening have a more favorable prognosis compared with symptomatic or interval cancers, debate continues as to whether this is due simply to stage migration or to underlying biological differences in the disease detected by different methods. The two studies we are concerned with here are by the same group, and are both based on the UK West Midlands Cancer Intelligence Unit’s registration data. In the first study, the authors examined the pathological features of screen-detected and symptomatic tumors and their associations with prognosis, thereby ascertaining whether the better survival rate of screen-detected breast cancers is attributable to shifts in standard prognostic features [1]. In the second study, they performed a similar analysis on a largely similar dataset, but also explored and adjusted survival estimates for the confounding factor of “lead-time bias” [2].