Postoperative treatment outcome in canine mammary tumors. Multivariate analysis of the prognostic value of pre- and postoperatively available information.

OBJECTIVE

Mammary tumors belong to the most common canine neoplasias. Few data are available on postoperative outcome and independent prognostic value of variables including pre-operatively available parameters such as cytology. The aim of this study was to characterize outcome following surgery and identify independent prognostic factors in canine mammary tumors.

MATERIAL AND

METHODS

Prospective study in which dogs with mammary tumors underwent surgical tumor removal followed by histopathologic examination of the neoplasias. Kaplan-Meier log rank analysis and multivariate regression analyses were used to evaluate survival, recurrence-free interval (RFI) and metastasis free interval (MFI) as well as independent influence of variables on outcome.

RESULTS

134 dogs with mammary tumors were included. In 126 dogs without distant metastasis, overall survival duration was 1113 d; median RFI and MFI were not reached. Histologic grade showed independent influence on duration of RFI (p=0.040), MFI (p=0.007), and survival (p=0.029). Median survival in benign (n=98), grade 1 (n=10) and grade 2 (n=16) malignant tumors was 1319 d, 670 d, 406 d, respectively. Cytology exerted independent influence on the likelihood for recurrence (p=0.013), duration of RFI (p=0.026) and survival (p=0.030).

CONCLUSION AND CLINICAL RELEVANCE: Histologic grade was of independent prognostic significance for postoperative outcome in this population of dogs with mammary tumors. As a pre-operatively available parameter, cytology may also possess prognostic value in canine mammary neoplasias.