Table 1.

Incidence of spontaneous gastric and intestinal neoplasms in control F344/N rats and B6C3F1 mice from recent NTP chronic (two-year) bioassay studies (in percentages).^a

Site and diagnosis	Male rat (1,398)b	Female rat (1,350)	Male mouse (1,449)	Female mouse (1,498)
Forestomach
Squamous cell papilloma	0.2	0.3	1.4	1.7
Squamous cell carcinoma	0	0.1	0.5	0.1
Combined	0.2	0.4	1.8	1.9
Glandular stomach
Adenoma	0	0	0	0.1
Adenocarcinoma	0	0	0	0.1
Neuroendocrine tumor	0	0	0	0
Combined	0	0	0	0.2
Small intestine
Adenoma	0	0	0.9	0.5
Adenocarcinoma	0.1	0	1.6	0.3
Combined	0.1	0	2.4	0.8
Large intestine
Adenoma	0.1	0.2	0	0
Adenocarcinoma	0.1	0.1	0.3	0
Combined	0.2c	0.3c	0.3d	0

^aNTP Historical Controls Report (May 2009). There were 49 to 50 animals per group for 27 to 30 studies regardless of the route of administration reported in the past 5 years. The rat strain is F344/N and mouse strain B6C3F1.

^bNumber of animals (n).

^cAll were in colon or rectum.

^dAll 4 were in the cecum.