For multivariate modelling, we included statistically significant variables, or those trending toward significance ( P < 0.10), as well as age and duration of immunosuppression, which are important clinical risk factors. 6 History of BCC and multiple first CSCC remained independent predictors for further CSCC ( Figure 3 b and c ).
The proportion of patients with a first “high-grade” CSCC varied across centers (AJCC8 range: 5%–50% and BWH 0%–20%, Figure 1 d), although this did not reach statistical significance ( P = 0.23 and 0.75 for AJCC8 and BWH, respectively, chi-square test).
Male sex, high-risk CSCC, by either BWH (HR: 2.0) or the Actinic Damage and Skin Cancer Index (HR: 1.7), and multiple first CSCC (HR: 2.2) showed a trend toward increased risk, without reaching significance ( P : 0.06–0.08).