Evaluation of neoadjuvant prednisone administration and surgical excision in treatment of cutaneous mast cell tumors in dogs.
OBJECTIVE
To determine response rate and reduction in tumor burden and effect of dose on tumor response in dogs treated with neoadjuvant prednisone for cutaneous mast cell tumors (MCTs).


METHODS
Combined prospective clinical study and retrospective case series.


METHODS
49 dogs with MCT.


METHODS
Medical records were retrospectively reviewed for dogs with primary untreated cutaneous MCT managed with neoadjuvant prednisone administration and surgery. Tumor characteristics and response to treatment were recorded. A subset of dogs assigned to low-dose (LD) treatment with neoadjuvant prednisone (1.0 mg/kg [0.45 mg/lb], PO, q 24 h) or high-dose (HD) treatment (2.2 mg/kg [1.0 mg/lb], PO, q 24 h) was used to determine the effects of dose.


RESULTS
The overall objective response rate was 70% for dogs treated with neoadjuvant prednisone; prednisone dose was not significantly associated with response. Prospectively, the median sum maximal diameter (MaxD) reduction was 45.2%, and reduction in tumor volume was 80.6%. In both treatment groups, the mean percentage MaxD reduction and tumor volume reduction were significant. The difference in response between the LD and HD groups was not significant. The LD group had mean MaxD and tumor volume reductions of 35.4% and 52.5%, respectively, compared with mean reductions of 48.8% in MaxD and 78% in tumor volume in the HD group.


CONCLUSIONS
Treatment with neoadjuvant prednisone appears to be useful for inducing reduction of MCTs and may facilitate resection when adequate surgical margins cannot be confidently attained because of mass location or size or both.
Stanclift
Rebecca M
RM
Sonora Veterinary Specialists, Phoenix, AZ 85032, USA.
Gilson
Stephen D
SD
D000818:Animals; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use*; D003131:Combined Modality Therapy / Q000662:veterinary; D018572:Disease-Free Survival; D004283:Dog Diseases / Q000188:drug therapy* / Q000473:pathology / Q000601:surgery; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005260:Female; D008297:Male; D012515:Mast-Cell Sarcoma / Q000188:drug therapy / Q000473:pathology / Q000601:surgery / Q000662:veterinary*; D009364:Neoplasm Recurrence, Local; D009367:Neoplasm Staging; D011241:Prednisone / Q000627:therapeutic use*; D011446:Prospective Studies; D011897:Random Allocation; D012189:Retrospective Studies; D012878:Skin Neoplasms / Q000188:drug therapy / Q000473:pathology / Q000601:surgery / Q000662:veterinary*; D016896:Treatment Outcome
D018931:Antineoplastic Agents, Hormonal; D011241:Prednisone