Survival in cancer patients with previous hospitalization for sarcoidosis: a Swedish population-based cohort study during 1964-2006

Sarcoidosis has been reported to be associated with an increased risk of cancer; however, little information is available about the prognosis for sarcoidosis patients diagnosed with cancer.

A population-based cohort of sarcoidosis patients was identified from Swedish registers. Cause-specific and overall hazard ratios (HRs) were estimated by using Cox regression model to show the probability of death in the study group compared with the control population.

A total of 1167 sarcoidosis patients were identified with subsequent cancer compared with 1,023,725 cancer patients without sarcoidosis from 1964 to 2006, showing a significant survival disparity [overall HR 1.21, 95% confidence interval (CI) 1.13-1.30 and cause-specific HR 1.16, 95% CI 1.08-1.27]. Site-specific analyses revealed that an overall mortality excess in sarcoidosis patients was observed for six cancers in comparison with a cancer-specific mortality excess for four cancers. Notably, stratified analyses showed that the prognosis was worse for cancer patients diagnosed below age 65 years. Cancer sites with significant mortality excess after sarcoidosis were mutually exclusive for men and women.

A previously diagnosed sarcoidosis worsens the prognosis of cancer, preferentially for those diagnosed at a relatively younger age. The underlying mechanisms and more prognostic factors warrant further investigation.