Retrospective, population-based cohort study of the incidence of cancer in patients with morphea and systemic sclerosis

Systemic sclerosis (SSc) is associated with increased risk of cancer, but population-level data on cancer risk in morphea are limited and conflicting. A retrospective, population-based cohort study in Quebec (Canada) investigated the incidence and standardized incidence ratios (SIRs) of overall and site-specific cancers in patients with morphea and SSc compared with the general population. In administrative health databases (1996-2019) the authors identified 6181 patients with morphea and 8133 patients with SSc. During follow-up through 2020, 782 patients with morphea (12.65%) and 1104 with SSc (13.47) developed cancer. Overall cancer incidence was increased in both the morphea cohort (SIR 1.24; 95% CI 1.14-1.35) and the SSc cohort (1.37; 1.27-1.48). Solid tumor risk was elevated in both cohorts (morphea SIR 1.17; 95% CI 1.06-1.29 and SSc 1.21; 1.11-1,32). Hematologic cancer risk was markedly elevated among patients with SSc (SIR 2.40; 95% CI 1.92-2.96) but not statistically significant among patients with morphea (1.34; 0.97-1.81). Female reprductive and breast cancers predominated in the morphea group; lung cancer was most frequent among patients with SSc. Immunosuppresant use was associated with lower cancer risk among patients with morphea (HR 0.56; 95% CI 0.46-0.68) and those with SCc (0.63; 0.55-0.70) The authors conclude that these findings suggest that morphea and SSc are associated with increased cancer risk compared to the general population, with distinct cancer profiles between the two conditions.