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Background Mammographic screening has led to a proportional shift toward earlier-stage breast cancers at presentation. We assessed whether the method of detection provides prognostic information above and beyond standard prognostic factors and investigated the accuracy of predicted overall and breast cancer–specific survival by the computer tool Adjuvant! among patients with screen-detected, interval, and nonscreening-related carcinomas. Methods We studied 2592 patients with invasive breast cancer who were treated at the Netherlands Cancer Institute from January 1, 1990, through December 31, 2000. Overall and breast cancer–specific survival probabilities among patients with mammographically screen-detected (n = 958), interval (n = 417), and nonscreening-related (n = 1217) breast carcinomas were compared. Analyses were adjusted for clinicopathologic characteristics and adjuvant systemic therapy. Because of gradual implementation of population-based screening in the Netherlands, analyses were stratified a priori according to two periods of diagnosis. All statistical tests were two-sided. Results Screen detection was associated with reduced mortality (adjusted hazard ratio for all-cause mortality = 0.74, 95% confidence interval = 0.63 to 0.87, P < .001, and adjusted hazard ratio for breast cancer–specific mortality = 0.62, 95% confidence interval = 0.50 to 0.78, P < .001, respectively) compared with nonscreening-related detection. The absolute adjusted reduction in breast cancer–specific mortality was 7% at 10 years. The prognostic value of the method of detection was independent of the period of diagnosis and was similar across tumor size and lymph node status categories, indicating its prognostic value beyond stage migration. Adjuvant! underestimated breast cancer–specific survival in patients with screen-detected (−3.2%) and interval carcinomas (−5.4%). Conclusions Screen detection was found to be independently associated with better prognosis for overall and breast cancer–specific survival and to provide prognostic information beyond stage migration among patients with invasive breast cancer. We propose that the method of detection should be taken into account when estimating individual prognosis. [ABSTRACT FROM PUBLISHER]

The article comments on a paper which reports the changes in screening mammography, menopausal hormone therapy, and breast cancer incidence in the Kaiser Permanente Northwest health plan. The authors stress that the researchers have failed to consider on what causes the decline in incidence between 2000 and 2004. A randomized trial is considered not helpful in population studies. The authors also emphasize that the paper is not done at the level of individual patient data.