Canine Mammary Tumors as a Potential Model for Human Breast Cancer in Comparative Oncology

Table 3

Analyses of predictor variables in relation to subtypes of canine mammary tumors.

Variable	Tumor subtypes (mean ± SD)				value (among groups)
	Luminal A	Luminal B	Triple negative	HER2-enriched
Tumor size (cm)	2.28 ± 1.33	3.06 ± 1.24	5.01 ± 1.43	3.43 ± 1.05	<0.001
Ki67 expression	6.55 ± 3.94	21 ± 7.68	34.11 ± 5.75	24.7 ± 8.67	<0.001
Vet-NPI	2.2 ± 1.1	3.25 ± 1.39	5.34 ± 0.92	3.89 ± 1.2	<0.001

One-way ANOVA was applied to compute the values among different subtypes of 64 canine mammary tumors. All variables displayed significant differences (), so that triple-negative tumors showed the highest mean compared with other subtypes. Veterinary Nottingham Prognostic Index (Vet-NPI) was computed as: Vet-NPI = [tumor size (cm) × 0.2] + histological grade (1, 2, or 3) + evidence of vascular invasion and/or regional lymph node metastases (1 or 2 if absent or present, respectively). SD, standard deviation.