Systemic sclerosis and the risk of cancer: a nationwide population-based cohort study

Abstract

Background: Earlier studies reported an increased cancer risk among patients with systemic sclerosis. Study size limitations and paucity of population-based study designs may have resulted in imprecise risk estimates.

Objectives: To assess cancer risk among patients with systemic sclerosis in a nationwide follow-up study.

Methods: Patients with a first diagnosis of systemic sclerosis from 1977 to 2006 were identified from the nationwide Danish National Registry of Patients (DNRP), whose records encompass all hospitalizations and outpatient visits. Patients' DNRP records were linked to the Danish Cancer Registry. We compared their cancer incidence with that expected from cancer incidence in the general population, calculating standardized incidence ratios (SIRs) and 95% confidence intervals (CIs).

Results: Two thousand and forty patients with systemic sclerosis were identified and followed for 16,003 person-years, with a median follow-up time of 6·4 years (interquartile range 2·2-11·5). Among these patients, 222 cases of cancer were identified. The overall SIR for cancer was 1·5 (95% CI 1·3-1·7), with a gender-specific SIR of 2·2 (95% CI 1·7-2·8) for men and 1·3 (95% CI 1·1-1·6) for women. The most frequent cancers were smoking- and alcohol-related cancers including lung cancer (SIR = 1·6, 95% CI 1·2-2·0), haematological cancers (SIR = 2·5, 95% CI 1·5-4·0) and immune-related cancers (SIR = 1·4, 95% CI 1·0-1·9).

Conclusions: Systemic sclerosis is a risk factor for cancer, particularly smoking- and alcohol-related cancers. Men with systemic sclerosis generally are at higher cancer risk than women. Both primary and secondary cancer preventive measures are needed in the care of patients with systemic sclerosis.