TABLE 4.

Frequency of surveillance colonoscopy following proctectomy for rectal cancer in mismatch repair gene mutation carriers

Colonoscopy	All No. (%)	Metachronous cancer
		Absent No. (%)	Present No. (%)
At least one	62 (78)	43 (90)	19 (95)
Average frequency*
Every year	46 (74)	33 (76)	13 (68)
Every 2 years	8 (13)	6 (14)	2 (11)
Every 3 years	2 (3)	2 (5)	0 (0)
Unknown frequency	6 (10)	2 (5)	4 (21)
Mean interval (year) for 1 examination (95 % CI)	1.16 (1.01–1.31)	1.17 (0.97–1.36)	1.13 (0.94–1.33)
None	6 (8)	5 (10)	1 (5)
Missing	11 (14)	10	1
Total	79	58	21

^*Extracted from the self-reported questionnaire data. The frequency of colonoscopy was assumed to be distributed uniformly in the period between first and last age of colonoscopy