Incidence of cancer among patients with systemic sclerosis.

Background: To determine cancer risk among patients with systemic sclerosis and localized scleroderma, a population-based retrospective cohort study was performed. Patients in Sweden with a discharge diagnosis of systemic sclerosis or localized scleroderma were obtained from the computerized database of hospital discharge diagnoses for the years 1965-1983. Nine hundred seventeen patients with systemic sclerosis and 102 with localized scleroderma were identified.

Methods: Using record linkage analysis with data from the Swedish National Cancer Registry, standardized incidence ratios (SIR)s (the ratio of observed to expected incidence) were calculated for specific cancer sites.

Results: The SIR for developing cancer in the cohort with systemic sclerosis was 1.5 (95% CI, 1.2-1.9). For specific cancer sites, risks were elevated for lung cancer (SIR, 4.9; 95% CI, 2.8-8.1), nonmelanoma skin cancers (SIR, 4.2; 95% CI, 1.4-9.8), and primary liver cancer (SIR, 3.3; 95% CI, 1.1-7.6). There was a suggestive increase in hematopoietic cancers (SIR, 2.3; 95% CI, 0.9-4.8). In contrast, cancer risks in the similarly ascertained cohort with localized scleroderma were no different from those of the general population.

Conclusions: This study confirms earlier reports of an association between systemic sclerosis and an increased risk of cancer. Specific tumor sites correspond to the sites commonly affected by fibrosis such as the lung and skin.