Abstract
Background
Chronic inflammatory bowel disease (IBD) and Lynch syndrome (LS) are associated with an increased risk for developing colorectal cancer (CRC). After 8-10 years of pan-ulcerative colitis (DC), the risk of CRC is 2%, increasing by 0.5-1.0% annually. LS has been associated with a 60-80% lifetime risk of CRC. It is unclear whether individuals diagnosed with both IBD and LS would have a cumulative risk or earlier age of onset of CRC based on their diagnoses.
Method
Patients with IBD and a germline mismatch repair gene (MMR) mutation were identified through the Familial Gastrointestinal Cancer Registry at Mount Sinai Hospital in Toronto, Canada. Information on their IBD diagnosis, colorectal screening/surgery, medication use, family history and genetic test results were collected (Table 1).
Table 1.
| Case # | 1 | 2 | 3 | 4 | 5 | |
|---|---|---|---|---|---|---|
| Gender | M | F | F | M | F | |
| Ethnicity | Caucasian | Jewish | Caucasian | Caucasian | Caucasian | |
| MMR Mutation | MLH1 | MSH2 | MSH2 | MSH2 | MSH6 | |
| Age of IBD dx | 27 | 20 | 27 | 32 | 23 | |
| Site of IBD | Ileum | Pancolitis | Pancolitis | Proctitis | Pancolitis | |
| Colectomy, age | 21 | 57 | 43 | 44 | 63 | |
| Cancer/dysplasia | CRC dx 21 | LGC* | None | TVA/HGD** dx 44 | Endometrial dx 57 | |
| Smoking hx | N | Y | N | Y | N | |
| IBD medication | 5-ASA | N | Y | Y | Y | Y |
| Steroids | N | Y | Y | N | Y | |
| Antibiotics | N | Y | Y | Y | N | |
| Age of CRC in 10 or 20 kin | # of kin | 2 | 3 | 2 | 4 | 5 |
| Mean age | 40.5 | 30.7 | 35.5 | 49.7 | 78.4 |
*LGD – low-grade dysplasia on random screening biopsy
**TVA/HGD – tubulovillous adenoma with foci of high-grade dysplasia
Results
Five of 329 (1.5%) individuals with germline MMR mutations reported having a history of IBD.
Conclusions
Concurrent IBD and LS did not appear to predispose to early-onset CRC in our small case series.