Tumor-associated macrophages (TAMs) are known to influence neoplastic processes and regulate many traits of malignancy (eg, tumor cell invasion into neighboring tissues, matrix remodeling, angiogenesis, tumor seeding, inflammation). In human cases of breast cancer, TAMs are associated with increased metastasis and a worse prognosis. In dogs, however, the prognostic value of TAMs has not previously been evaluated.
This study evaluated TAMs in canine mammary tumors (CMTs) to determine whether TAMs were associated with prognosis. Immunohistochemical expression of the mouse monoclonal antibody MAC387 was used to quantify TAM values in 59 CMTs (20 benign and 39 malignant tumors). Higher TAM values were noted in malignant tumors and were associated with skin ulceration, solid carcinomas, nuclear grade, and tubular differentiation. Higher TAM levels were also significantly associated with decreased survival time. The authors concluded that TAMs can be a prognostic indicator in CMTs and recommended further research focused on inhibiting TAMs, which could provide a potential new CMT therapy.