Background: Limited data are available on the prognostic performance of Adjuvant! Online (AOL) and Nottingham Prognostic
Index (NPI) in young breast cancer patients.
Methods: This multicentre hospital-based retrospective cohort study included young (p40 years) and older (55–60 years) breast
cancer patients treated from January 2000 to December 2004 at four large Belgian and Italian institutions. Predicted 10-year
overall survival (OS) and disease-free survival (DFS) using AOL and 10-year OS using NPI were calculated for every patient. Tools
ability to predict outcomes (i.e., calibration) and their discriminatory accuracy was assessed.
Results: The study included 1283 patients, 376 young and 907 older women. Adjuvant! Online accurately predicted 10-year OS
(absolute difference: 0.7%; P1⁄40.37) in young cohort, but overestimated 10-year DFS by 7.7% (P1⁄40.003). In older cohort, AOL
significantly underestimated both 10-year OS and DFS by 7.2% (Po0.001) and 3.2% (P1⁄40.04), respectively. Nottingham Prognostic
Index significantly underestimated 10-year OS in both young (8.5%; Po0.001) and older (4.0%; Po0.001) cohorts. Adjuvant! Online
and NPI had comparable discriminatory accuracy.
Conclusions: In young breast cancer patients,
