Characteristics of the patient cohorts classified according to their T stage.

T stage according to tumor thickness at diagnosis, classified according to AICC 7th edition (2009).% indicates % of group, except Number of Patients, where % indicates % of total. Thickness: thickness of primary tumor. Resection: pathological description of resection status. Survival: overall survival. OD: observed deaths. CO: censored outcomes, N/A: not applicable (median could not be calculated, as over half the cases in this group were censored).Characteristics of the patient cohorts classified according to their T stage.