Validation of the prognostic value of histopathological grading or c-kit mutation in canine cutaneous mast cell tumours: A retrospective cohort study

摘要

The objective of this retrospective cohort study was to validate the prognostic value of histological grading of canine cutaneous mast cell tumours (MCTs) according to the Patnaik (grades I—III3 and Kiupel (low, high) grading systems, and to confirmthe prognostic significance of internal tandem duplications (ITDs) within exon 11 of the c-fcit gene (ITD-Exonl 1). The baseline characteristics and outcome data from 47 dogs diagnosed with cutaneous MCTs were collected and reviewed. Tumours were gradedaccording to both grading systems and the nucleotide sequence of c-fcit was evaluated. Results were analyzed to evaluate predictive factors for overall survival (OS) and progression-free survival (PFS).Log-rank tests indicated that dogs with Patnaik grade III MCTs had significantly reduced OS and PFS compared to those with either grade I or II tumours. However, no significant difference in OS or PFS was observed between grade I and II tumours. The dogswith Kiupel high-grade MCTs had significantly shorter OS and PFS than dogs with low-grade MCTs. The presence of ITD-Exonl 1 was significantly associated with shorter PFS. The result of Cox regression analysis showed that the Kiupel grading system for OSand PFS, and lymph node metastasis for OS, independently predicted prognosis. Kappa statistics confirmed a significantly higher inter-observer consistency for the Kiupel compared to the Patnaik grading system. These findings demonstrate that the Kiupelgrading system is a useful prognostic tool for canine cutaneous MCTs in predicting OS and PFS, while the occurrence of ITD-Exonl 1 appeared to be a useful predictor for PFS.