Data concerning small bowel adenocarcinoma (SBA) in Crohn's disease (CD) come from case reports and small retrospective series. The aim of this study was to further describe SBA in patients with CD and compare it with SBA de novo.
Twenty patients with CD with SBA recruited in French university hospitals were studied and compared with 40 patients with SBA de novo recruited from a population-based registry. SBA occurred after a median time of 15 years of CD and was located within the inflamed areas of the ileum (n = 19) or jejunum (n = 1), whereas in patients with SBA de novo, it was distributed all along the small intestine. Median age at diagnosis of SBA was 47 years (range, 33-72 yr) in patients with CD and 68 years (range, 41-95 yr) in those with SBA de novo.
The cumulative risk of SBA, assessed in a subgroup of patients, was 0.2% and 2.2% after 10 and 25 years of ileal CD, respectively. SBA accounted for 25% and 45% of the risk of gastrointestinal carcinoma after 10 and 25 years of CD, respectively. Diagnosis was made preoperatively in 1/20 patients with CD and 22/40 patients with SBA de novo. Signet ring cells were found in 35% of patients with CD but not in patients with SBA de novo. Relative survival was not significantly different in these 2 categories of patients (54 versus 37% and 35 versus 30% in patients with and without CD at 2 and 5 yr, respectively).
SBA in CD is different from SBA de novo. It arises from longstanding ileal inflammation and is difficult to diagnose. SBA cumulative risk increases after 10 years of CD and is likely to cause premature mortality in patients with early-onset CD.