Fig. 3

Univariable analysis of non-linear effects for age, tumor size, and number of positive lymph nodes using MFP (3a–c) and RCS (3d–f). For each factor X, an estimate of the relative hazard is shown as a function of X. The estimate is based on a Cox model with fractional polynomial transformation of X. A reference value was chosen for each factor (35 for age, 20 for tumor size, and zero for number of positive lymph nodes). The relative hazard for this value will be 1.00 per definition. For other values of each factor the relative hazard will be an estimate with a corresponding 95% CI shown as a band around the point estimate. The shaded area in the background is a kernel density estimate of the distribution of each factor and the dots represent the values observed