Use of alternating administration of carboplatin and doxorubicin in dogs with microscopic metastases after amputation for appendicular osteosarcoma: 50 cases (1999-2006).
OBJECTIVE
To evaluate the efficacy and toxicity of an alternating carboplatin and doxorubicin chemotherapy protocol in dogs with putative microscopic metastases after amputation for appendicular osteosarcoma and assess patient-, tumor-, and treatment-related factors for associations with prognosis.


METHODS
Retrospective case series.


METHODS
50 client-owned dogs.


METHODS
Records of dogs that underwent amputation for appendicular osteosarcoma and received an alternating carboplatin and doxorubicin chemotherapy protocol were reviewed. Dogs had full staging and were free of detectable metastases prior to chemotherapy. Data on disease-free interval (DFI), survival time, and toxicoses were retrieved from medical records and owner or referring veterinarian communications.


RESULTS
Median DFI was 202 days. Median survival time was 258 days. Twenty-nine (58%) dogs completed the protocol as planned, and the rest were withdrawn typically because of metastases or toxicoses. Grade 3 or 4 myelosuppression was reported in 9 of 50 (18%) dogs and grade 3 or 4 gastrointestinal toxicosis in 6 of 50 (12%) dogs. There were no chemotherapy-related fatalities. Univariate factors associated with significant improvement in DFI included tumor location (radius), receiving doxorubicin as the first drug, starting chemotherapy more than 14 days after amputation, and no rib lesions on preamputation bone scans. Multivariate factors associated with a significant improvement in survival time were tumor location (radius) and completing chemotherapy.


CONCLUSIONS
Alternating administration of carboplatin and doxorubicin resulted in DFI and survival time similar to those reported for single-agent protocols. Clients should be counseled regarding the likelihood of toxicoses. Relevance of sequence and timing of starting chemotherapy should be further evaluated.
Bacon
Nicholas J
NJ
Animal Cancer Center, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
Ehrhart
Nicole P
NP
Dernell
William S
WS
Lafferty
Mary
M
Withrow
Stephen J
SJ
D000671:Amputation, Surgical / Q000662:veterinary; D000818:Animals; D000970:Antineoplastic Agents / Q000009:adverse effects / Q000627:therapeutic use*; D001859:Bone Neoplasms / Q000188:drug therapy / Q000401:mortality / Q000601:surgery / Q000662:veterinary*; D016190:Carboplatin / Q000009:adverse effects / Q000627:therapeutic use*; D018572:Disease-Free Survival; D004283:Dog Diseases / Q000188:drug therapy* / Q000401:mortality / Q000601:surgery; D004285:Dogs; D004317:Doxorubicin / Q000009:adverse effects / Q000627:therapeutic use*; D005260:Female; D008297:Male; D009362:Neoplasm Metastasis; D012516:Osteosarcoma / Q000188:drug therapy / Q000401:mortality / Q000601:surgery / Q000662:veterinary*; D012189:Retrospective Studies; D012449:Safety; D016019:Survival Analysis; D013997:Time Factors; D016896:Treatment Outcome
D000970:Antineoplastic Agents; D004317:Doxorubicin; D016190:Carboplatin