Survival in cancer patients hospitalized for inflammatory bowel disease in Sweden

The increased cancer risk among patients diagnosed with inflammatory bowel disease (IBD) is well reported, whereas studies regarding the cancer prognosis with IBD have shown conflicting results. We aimed at assessing and quantifying the cause-specific and overall mortality among cancer patients with IBD compared to those without IBD.

The population-based Swedish registers were used to identify cancer patients diagnosed with or without IBD. We used a Cox regression model to estimate hazard ratios (HRs) for cause-specific and overall mortality, showing the probability of death in the study group compared to the reference.

A total of 2462 cancer patients with IBD and 1,011,894 cancer patients without IBD were ascertained from 1964 to 2006, showing a significant survival disparity (overall HR, 1.26; 95% confidence interval [CI]: 1.20-1.33 versus cause-specific HR, 1.22; 95% CI: 1.15-1.29). Although worse overall cancer mortality with IBD was widely observed, the worse cause-specific mortality was only confined to colorectal cancer (CRC). There was no difference in TNM staging among cancer patients with or without IBD. Stratified analyses showed that a worse prognosis was more pronounced in younger patients (<60 years) and in men. Discordant malignant neoplasms and cardiovascular diseases were noted to be associated with increased mortality in the study group.

Previously diagnosed IBD worsens the prognosis of cancers, especially for CRC. The more pronounced effect was noted among younger patients and in men. The underlying mechanisms warrant further investigation.