Table 1. Colon tumor incidence, pathological characteristics, numbers in both DMH-treated and control groups.

Week	n	Incidence n (%)		Pathological characteristics (n)		Tumor numbers (n)
		Control	DMH	Ad	Ca	1	2	>2
12th	3	0 (0)	1 (33.3)	1	0	1	0	0
14th	3	0 (0)	2 (66.7)	2	0	1	0	1
16th	3	0 (0)	2 (66.7)	2	0	0	1	1
18th	3	0 (0)	3 (100.0)	3	0	1	0	2
20th	3	0 (0)	3 (100.0)	3*	2	0	0	3
22th	13	0 (0)	11 (84.6)	9*	11	1	2	8
Total	28	0 (0)	22 (78.6)	18	13	4	3	15

Pathological characteristics, tumor numbers referred to data from DMH-treated group because no tumor data was available in control group. (n): number of rats; Ad: adenoma; Ca: carcinoma; *the number of rats will be summarized here no matter there are colonic carcinomas exist in DMH-treated animals.