Table 5.

Summary of neoplasms with statistically significant differences in incidence rates between the two strains of control female rats (Fischer 344/N versus Hsd:Sprague Dawley SD) by at least one criterion in our analysis of 18 NTP studies.

			Statistically Significant Strain Difference in Incidence Rates?
	Incidence Rate (%)a		Matched on Vehicleb		Not Matched on Vehicleb
Neoplasm	Fischer 344/N	Sprague Dawley	with Bonferronic	without Bonferronic	with Bonferronic	without Bonferronic
Clitoral Gland Adenoma	5.82	0.22	+	+	+	+
Mammary Gland Carcinoma	2.44	10.15	+	+	+	+
Mammary Gland Fibroadenoma	48.44	67.44	+	+	+	+
Mononuclear Cell Leukemia	16.67	0.85	+	+	+	+
Thyroid Gland C cell Adenoma	13.56	25.43	+	+	+	+
Lung Alveolar/Bronchiolar Adenoma	2.00	0.42	+	+		+
Thyroid Gland C cell Carcinoma	1.33	3.85		+	+	+
Clitoral Gland Carcinoma	1.34	0.00		+		+
Malignant Mesothelioma	0.89	0.00		+		+
Pituitary Gland Pars Distalis Adenoma	44.67	38.85		+
Adrenal Medulla Benign Pheochromocytoma	2.89	7.23			+	+
Pituitary Gland Pars Intermedia Adenoma	0.00	1.06				+
Skin Basal Cell Adenoma	1.11	0.21				+
Thyroid Gland Follicular Cell Carcinoma	1.11	0.21				+
Uterus Carcinoma	0.22	1.27				+

^aRates obtained from Table 2 and based on nine studies per strain, matched on laboratory (Battelle Columbus), diet (NTP-2000), and route (gavage).

^bSome analyses further matched on vehicle (corn oil) and some did not (corn oil or water).

^cThe Bonferroni correction adjusts for multiple testing because a separate test was performed for each of the 82 tumor types.