To assess colorectal cancer (CRC) risk during colonoscopy surveillance in a cohort of patients with the serrated polyposis syndrome (SPS).
Colonoscopy and histology records from January 2000 to time of interview for 67 New Zealand patients, meeting WHO criteria for a diagnosis of SPS and enrolled in the Genetics of Serrated Neoplasia study, were reviewed. Polyp demographics, smoking status and family history of cancer were recorded.
Of 67 patients 18 presented with CRC (mean age 57yrs, 12 Female). Only one of 18 reported a first degree relative (FDR) with CRC. Over a median follow-up of 8 years from time of surgery with an average interval of 16 months between colonoscopies, two patients developed metachronous CRC: one identified at prophylactic completion colectomy and one in association with first diagnosis of SPS 19 yrs following initial CRC and 30 months after a previous colonoscopy. Of 45 patients with polyps alone (mean age 48 yrs, 27 female) followed for a median of 9 years with an average interval of 15 months between colonoscopies, none developed CRC despite 33 having multiple pan colonic polyps. Of these 33, 70% had an adenoma, 18 % a sessile serrated polyp and 53 % polyps >10 mm. A FDR with CRC was reported in 14/45 (31%). Four patients with multiple pan colonic polyps and no FDR with CRC underwent prophylactic subtotal colectomy (mean age 58 yrs, 3 females) after being followed for a median of 5 years with an average interval between colonoscopies of 8 months. All had adenomas and one a sessile serrated polyp. No significant smoking effect was seen in any group.
If endoscopic control is feasible, SPS patients can be judiciously managed by frequent surveillance colonoscopy.