Chemotherapy for dogs with lymph node metastasis from histiocytic sarcomas.

Background: Histiocytic sarcomas (HS) frequently metastasise, most commonly to visceral sites, but also to regional lymph nodes. Nodal metastases are associated with a poorer prognosis. This retrospective study aimed to evaluate prognostic factors, including the effect of adjuvant chemotherapy, on survival in dogs with nodal, but not systemic, metastases from HS.

Methods: Retrospective case series of 12 dogs with histologically diagnosed HS metastatic to lymph nodes treated with surgery with and without adjuvant chemotherapy.

Results: All dogs had histological evidence of metastasis to lymph nodes, with no clinical evidence for metastasis to viscera. Eight dogs that received chemotherapy had a median estimated survival of 219 days (range 77-1638 days); 1- and 2-year estimated survival rates were 37.7%. Median survival time for 4 dogs with nodal metastases that did not receive chemotherapy was 57 days (range 39-136 days) with none alive 1 year after surgery

Conclusion: Survival for dogs with only regional nodal metastases from HS appeared to be improved by adjuvant chemotherapy.