title: Ki-67 as a Prognostic Factor in Feline Mammary Carcinoma: What Is the Optimal Cutoff Value?
abstract: Ki-67 is a nuclear protein and a proliferation marker frequently used in establishing the prognosis for breast cancer patients. To investigate the prognostic value of the Ki-67 proliferation index in female cats with mammary carcinoma, a prospective study was conducted with 96 animals. The Ki-67 index of primary tumors (n = 96) was initially determined, and whenever possible, the Ki-67 index of regional lymph node metastasis (n = 38) and distant metastasis (n = 16) was also estimated. The optimal cutoff value for the Ki-67 index was determined by univariate and multivariate analysis. Ki-67 indices ≥ 14% were detected in 72.9% (70 of 96) of the tumors. Tumors with a Ki-67 index ≥ 14% were significantly associated with large size (P = .022), poor differentiation (P = .009), presence of necrotic areas (P = .008), estrogen receptor-negative status (P < .0001), fHER2-negative status (P = .003), and shorter overall survival (P = .012). Moreover, Ki-67 expression in the primary tumor was strongly and positively correlated with both regional metastasis (P < .0001; r = 0.83) and distant metastasis (P < .0001; r = 0.83), and was significantly higher in distant metastases when compared with the primary tumor (P = .0009). A similar correlation was also observed between regional and distant metastasis (P < .0001; r = 0.75). On the basis of the above results, the authors propose the adoption of the 14% value as the optimal cutoff for Ki-67 to identify tumors with high risk of disease progression.
authors.affiliation: CIISA, Faculdade de Medicina Veterinária, Universidade de Lisboa, Lisboa, Portuga.
authors.forename: M
authors.initials: M
authors.lastname: Soares
authors.affiliation: CIISA, Faculdade de Medicina Veterinária, Universidade de Lisboa, Lisboa, Portuga.
authors.forename: R
authors.initials: R
authors.lastname: Ribeiro
authors.affiliation: CIISA, Faculdade de Medicina Veterinária, Universidade de Lisboa, Lisboa, Portuga.
authors.forename: S
authors.initials: S
authors.lastname: Carvalho
authors.affiliation: CIISA, Faculdade de Medicina Veterinária, Universidade de Lisboa, Lisboa, Portuga.
authors.forename: M
authors.initials: M
authors.lastname: Peleteiro
authors.affiliation: CIISA, Faculdade de Medicina Veterinária, Universidade de Lisboa, Lisboa, Portuga.
authors.forename: J
authors.initials: J
authors.lastname: Correia
authors.affiliation: CIISA, Faculdade de Medicina Veterinária, Universidade de Lisboa, Lisboa, Portuga fernandof@fmv.ulisboa.pt.
authors.forename: F
authors.initials: F
authors.lastname: Ferreira
mesh_terms: D000818:Animals; D014408:Biomarkers, Tumor / Q000378:metabolism*; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology*; D002277:Carcinoma / Q000378:metabolism / Q000473:pathology*; D002371:Cat Diseases / Q000378:metabolism / Q000473:pathology*; D002415:Cats; D005260:Female; D019394:Ki-67 Antigen / Q000378:metabolism*; D008207:Lymphatic Metastasis; D015999:Multivariate Analysis; D011379:Prognosis; D011446:Prospective Studies
chemical_list: D014408:Biomarkers, Tumor; D019394:Ki-67 Antigen
keywords: Ki-67 proliferation index; cutoff value; feline mammary carcinoma; prognostic factor