Long‐term survival in dogs with localized histiocytic sarcoma treated with CCNU as an adjuvant to local therapy^*

Abstract

Histiocytic sarcoma (HS) is associated with a poor prognosis owing to the presence of metastasis at the time of diagnosis in most dogs. Improved outcome has been reported in several dogs with localized HS following local therapy, however, distant metastasis occurs in 70-91% of dogs suggesting that adjuvant systemic therapy is necessary. The purpose of this retrospective study was to describe clinical characteristics and outcome in dogs with localized HS treated with aggressive local therapy plus adjuvant CCNU chemotherapy. Data from 16 dogs were evaluated. The median disease-free interval was 243 days. Two dogs had local recurrence and eight dogs developed metastatic disease with a median time to relapse of 201 days in these 10 dogs. The median survival time for all 16 dogs was 568 days. These results support the recommendation for aggressive local therapy combined with adjuvant CCNU chemotherapy in dogs with localized HS.

Evaluation and comparison of outcomes in dogs with periarticular and nonperiarticular histiocytic sarcoma

“…In dogs, HS is typically associated with high metastatic potential and grave prognosis, [2][3][4]7 and previous reports 3,4,6 have encouraged the use of aggressive multimodal treatment to improve outcome. Recently, the MST for dogs with LHS in which tumors were reduced to microscopic disease with definitive local treatment followed by adjuvant lomustine was reported 6 to be approximately 19 months. In the present study, dogs in both the PAHS and non-PAHS groups that did not have evidence of measurable disease following definitive local treatment had MSTs that exceeded 1 year (510 [range, 83 to 980] and 400 [range, 27 to 918] days, respectively).…”

“…Localized HS arising near an appendicular joint has been reported in Rottweilers, 2,3,5,6 Labrador Retrievers, 2,3,5,6 Golden Retrievers, 2,3,5,6 and Flat-Coated Retrievers 2-6 and may represent a subtype of LHS. In a report by Craig et al, 3 18 tumors previously diagnosed as synovial cell sarcomas were reclassified as HS, and the overall MST for all 18 dogs was 5.3 months, but the treatments administered varied within this group.…”

“…6 In that study, aggressive multimodal treatment consisting of definitive local treatment and lomustine chemotherapy administered in an adjuvant setting resulted in an MST of 568 days. 6 On the basis of prior reports, we hypothesized that dogs with PAHS would have a longer survival time than would dogs with HS of other anatomic locations (non-PAHS), independent of metastatic disease presence, when both groups received treatment that consisted of chemotherapy, surgery, radiation, or a combination of these. The primary objective of the present study was to evaluate and compare the outcomes of dogs with PAHS and non-PAHS.…”

“…Chemotherapy agents varied, although the majority of dogs received lomustine, which is the only drug that has reported activity against HS. 6,7 Dogs with the periarticular form of HS may have a more favorable outcome than dogs with HS of other anatomic locations. This finding is independent of metastatic disease status, although the presence of metastatic disease in dogs with PAHS appears to be a negative prognostic indicator.…”

“…2 Localized HS appears to arise from a single site, typically Evaluation and comparison of outcomes in dogs with periarticular and nonperiarticular histiocytic sarcoma involving the lung, skin, subcutaneous tissues, bones, or joints. [2][3][4][5][6] Disseminated HS involves multiple organ systems, which could indicate metastasis and progression of the localized form. Alternatively, disseminated HS may be a primary multicentric disease, in which tumors arise simultaneously in multiple locations.…”