Table 4 Risk reduction according to stage and location of cancers.

Stage/location of cancer	History of screening colonoscopy		Cancers*	Adjusted odds ratios (95% CI)†
UICC stages 1 or 2	No colonoscopy		160 (94.1%)	1.00 Reference
	Colonoscopy	Any	10 (5.9%)	0.20 (0.10 to 0.40)
		1–4 years ago	4 (2.4%)	0.14 (0.05 to 0.38)
		5+ years ago	6 (3.5%)	0.30 (0.12 to 0.72)
UICC stages 3 or 4	No colonoscopy		155 (90.6%)	1.00 Reference
	Colonoscopy	Any	16 (9.4%)	0.28 (0.16 to 0.50)
		1–4 years ago	9 (5.3%)	0.25 (0.12 to 0.52)
		5+ years ago	7 (4.1%)	0.33 (0.14 to 0.75)
Proximal colon cancer	No colonoscopy		125 (89.3%)	1.00 Reference
	Colonoscopy	Any	15 (10.7%)	0.40 (0.21 to 0.72)
		1–4 years ago	9 (6.4%)	0.41 (0.20 to 0.87)
		5+ years ago	6 (4.3%)	0.38 (0.16 to 0.92)
Caecum and ascending colon	No colonoscopy		66 (85.7%)	1.00 Reference
	Any colonoscopy		11 (14.3%)	0.50 (0.25 to 1.00)
Other proximal colon cancer	No colonoscopy		60 (93.8%)	1.00 Reference
	Any colonoscopy		4 (6.3%)	0.24 (0.08 to 0.68)
Distal cancer (sigmoid or rectum)	No colonoscopy		208 (94.1%)	1.00 Reference
	Colonoscopy	Any	13 (5.9%)	0.17 (0.09 to 0.32)
		1–4 years ago	6 (2.7%)	0.12 (0.05 to 0.30)
		5+ years ago	7 (3.2%)	0.25 (0.11 to 0.57)
Sigmoid	No colonoscopy		64 (94.1%)	1.00 Reference
	Any colonoscopy		4 (5.9%)	0.13 (0.04 to 0.43)
Rectum	No colonoscopy		144 (94.1%)	1.00 Reference
	Any colonoscopy		9 (5.9%)	0.19 (0.09 to 0.39)

*For numbers and proportion of controls in respective categories, see table 3.

†Adjusted for age, sex, education, participation in general health screening examination, family history of colorectal cancer, smoking, body mass index, ever regular use of NSAIDs, ever regular use of HRT.

CI, confidence interval; HRT, hormone replacement therapy; NSAID, non‐steroidal anti‐inflammatory drug; UICC, Union Internationale Contre Cancer.