Small-bowel cancer in Lynch syndrome

Small-bowel cancer is part of the tumour spectrum of Lynch syndrome. Lynch syndrome, or hereditary non-polyposis colorectal cancer, is caused by germline mutations in one of the mismatch repair genes. Mutation carriers have an estimated lifetime risk for the development of small-bowel cancer of around 4%, corresponding to a relative risk of more than 100 compared with the general population. Patients with Lynch syndrome generally present with small-bowel cancer 10-20 years earlier than the general population, and small-bowel cancer might be the first clinical manifestation of Lynch syndrome. Tumours in patients with Lynch syndrome are evenly distributed within the small bowel. No specific risk factors, such as type of gene mutation, have been identified thus far. Screening for small-bowel cancer in Lynch syndrome has, until now, not been included in guidelines for surveillance, which might partly be due to the fact that, until recently, the possibilities for visualisation of the small bowel were limited. In view of the improved accessibility of the small bowel with the introduction of capsule endoscopy and double balloon enteroscopy, the question of whether patients should be screened for small-bowel neoplasia has regained attention. In this paper, we discuss the rationale for surveillance of small-bowel cancer in Lynch syndrome and highlight issues that need to be addressed in future studies before recommendations can be made.