Evaluation of prognostic markers for canine mast cell tumors treated with vinblastine and prednisone.
BACKGROUND
Canine cutaneous mast cell tumor (MCT) is a common neoplastic disease associated with a variable biologic behavior. Surgery remains the primary treatment for canine MCT; however, radiation therapy (RT) and chemotherapy are commonly used to treat aggressive MCT. The goals of this study were to evaluate the prognostic utility of histologic grade, c-KIT mutations, KIT staining patterns, and the proliferation markers Ki67 and AgNORs in dogs postoperatively treated with vinblastine and prednisone +/- RT, and to compare the outcome of dogs treated with post-operative chemotherapy +/- RT to that of a prognostically matched group treated with surgery alone. Associations between prognostic markers and survival were evaluated. Disease-free intervals (DFI) and overall survival times (OS) of dogs with similar pretreatment prognostic indices postoperatively treated with chemotherapy were compared to dogs treated with surgery alone.


RESULTS
Histologic grade 3 MCTs, MCTs with c-KIT mutations, MCTs with increased cytoplasmic KIT, and MCTs with increased Ki67 and AgNOR values were associated with decreased DFI and OS. Dogs with histologic grade 3 MCT had significantly increased DFI and OS when treated with chemotherapy vs. surgery alone. Although not statistically significant due to small sample sizes, MCTs with c-KIT mutations had increased DFI and OS when treated with chemotherapy vs. surgery alone.


CONCLUSIONS
This study confirms the prognostic value of histologic grade, c-KIT mutations, KIT staining patterns, and proliferation analyses for canine MCT. Additionally, the results of this study further define the benefit of postoperative vinblastine and prednisone for histologic grade 3 MCTs.
Webster
Joshua D
JD
Comparative Medicine and Integrative Biology Program, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA. jdwebste@purdue.edu
Yuzbasiyan-Gurkan
Vilma
V
Thamm
Douglas H
DH
Hamilton
Elizabeth
E
Kiupel
Matti
M
D000818:Animals; D004283:Dog Diseases / Q000175:diagnosis* / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D004285:Dogs; D020440:Gene Duplication; D053208:Kaplan-Meier Estimate; D008297:Male; D034701:Mastocytosis, Cutaneous / Q000188:drug therapy / Q000235:genetics / Q000473:pathology / Q000662:veterinary*; D011241:Prednisone / Q000627:therapeutic use*; D011379:Prognosis; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics; D012189:Retrospective Studies; D015996:Survival Rate; D016896:Treatment Outcome; D014747:Vinblastine / Q000627:therapeutic use*
D014747:Vinblastine; D019009:Proto-Oncogene Proteins c-kit; D011241:Prednisone