Fig. 4

ERBB2 mRNA investigated with subpopulation treatment effect pattern plot (STEPP) and survival analysis. STEPP investigated the relationship between mean ERBB2 mRNA (A) and the probability of being recurrence-free at the median recurrence-free survival (RFS) (8.7 years). The lower left corner shows the cutoff levels suggested by STEPP analysis and identified by positional scanning (PS). These cutoffs divided the cohort into three subgroups, namely low, intermediate and high. The locally estimated scatterplot smoothing curve fit is shown with the blue line. Kaplan–Meier estimates and multivariable Cox regression model of ERBB2 mRNA related to RFS (B). The study cohort was divided into three subgroups according to the suggested optimal first and second cutoffs for ERBB2 mRNA as shown in A. *The multivariable Cox regression model was adjusted for lymph node status, tumor size and stratified by estrogen receptor status. Adjusted hazard ratios (HR) with 95% confidence interval (CI) are presented