Lymph node status of felines affected by mammary gland neoplasms: a look beyond the presence or absence of metastasis.

The purpose of the present study was to assess the influence of gross and microscopic lymph nodes characteristics on overall survival time (OS) and to identify risk factors for lymph nodes metastasis in feline mammary gland tumors. A retrospective study was performed on a total of 198 lymph nodes from 158 female cats. Parameters such as the presence of metastasis, lymph node size in gross evaluation (gross maximum diameter), number of lymph nodes involved, number of metastatic foci, and metastatic focus size (microscopic maximum diameter) were evaluated. Additionally, the grade of extracapsular extension, tumor implant, tumor size, histological type, and histological grade were analyzed. Binary logistic regression was used to determine associations between lymph node diameter and tumor characteristics and lymph node metastasis. Follow-up time was measured so that prognostic factors could be associated with OS. Tumors classified as T2 (2-3 cm) and T3 (> 3 cm) had 2.56 and 2.15 times higher odds of presenting lymph node metastasis, respectively, while cribriform carcinoma had 2.47 times higher odds compared to tubulopapillary tumors. In addition, lymph nodes ≥1.5 cm had a risk of developing metastasis 2.5 times greater than lymph nodes <1.5 cm. Lymph node metastasis, gross maximum diameter (≥ 1.5 cm), macrometastasis, ≥ 2 involved lymph nodes, and grade III tumors were associated with shorter OS time (P < 0.05). Data suggest that in cats with mammary gland neoplasms, a complete pathological examination of lymph nodes and primary tumors is necessary for accurate prognostication and for guiding treatment strategies.