Long‐term outcomes of dogs undergoing surgical resection of mast cell tumors and soft tissue sarcomas: A prospective 2‐year‐long study

Abstract

ObjectiveReport clinical outcomes of dogs with surgically excised mast cell tumors (MCT) and soft tissue sarcomas (STS).Study designProspective clinical study.Sample populationFifty‐three dogs with 52 MCT (50 low grade, 2 high grade) and 19 STS (12 grade I, 6 grade II, 1 grade III).MethodsAll dogs were examined at 3, 6, 12, 18, and 24 months postoperatively, with cytologic or histopathologic evaluation of suspected local recurrences. Dogs euthanized because of study tumor‐related causes underwent necropsy.ResultsMedian intraoperative margins were 20 mm and 30 mm wide for MCT and STS, respectively, with 1 fascial plane resected en bloc. The narrowest histologic tumor‐free margins measured <1 mm in 21 of 52 (40%) MCT and 7 of 19 (37%) STS. All dogs were followed for 24 months. Two of 50 (4%) low‐grade MCT were diagnosed, with local recurrence 181 and 265 days postoperatively. Two of 36 (6%) dogs with low‐grade MCT developed visceral metastasis 181 and 730 days postoperatively. One of 2 dogs with high‐grade MCT developed local recurrence 115 days postoperatively. No local recurrence or metastasis was diagnosed after excision of 19 STS.ConclusionLocal recurrence rates among predominantly low‐ to intermediate‐grade MCT and STS were low, despite a high prevalence of histologic tumor‐free margins <1 mm. Surgical recommendations for high‐grade tumors cannot be extrapolated from this population.Clinical significanceSurgeons should seek to achieve microscopically complete excision for MCT and STS while minimizing patient morbidity and considering limitations of histopathology in predicting outcomes.

Ultrasound is a poor predictor of early or overt liver or spleen metastasis in dogs with high‐risk mast cell tumours

“…27,28,[44][45][46][47][48][49][50][51][52]55,60,61 Seven dogs lacked diagnostic liver cytology, therefore additional analysis was performed to exclude these dogs, which did not alter our 56 However we were consistent with current literature in the standards set forth at the start of the study. 53,56,72 Labradors were overrepresented at 45% of the canine population in this study. This is markedly higher than multiple previous reports that included 11%-27% Labradors.…”

“…The overall value of routine US and cytology of the liver and spleen in dogs with MCTs is unclear, because dogs with low-tointermediate grade tumours without negative prognostic factors have a favourable prognosis after surgery, even following incomplete or narrow margins. 20,50,53,54 However, routine hepatic and splenic cytologic assessment is probably useful for dogs at high-risk for visceral metastasis. 27,44 Cytologic evidence of early metastasis may be prognostic and alter treatment decisions.…”

Histologically low‐grade, yet biologically high‐grade, canine cutaneous mast cell tumours: A systematic review and meta‐analysis of individual participant data

“…Seventythree of these dogs were from a single study, 36 whereas the remaining 27 represent data from 4 additional studies. 9,22,24,37…”

“…The assessment of the risk of individual study bias is detailed in T A B L E 3 Assessment of the risk of bias a of individual studies included in the present meta-analysis Fox et al 38 Horta et al 9 Marconato et al 36 Milovancev et al 37 Moirano et al 39 Olsen et al 22 Pizzoni et al 40 Weishaar et al 24…”

“…cally examined in the previous study was the effect of lymphadenectomy in dogs with WHO stage II cMCT, which was determined to reduce risk of tumour progression and tumour-related death by 5.47 and 3.61 times, respectively. The present IPD metaanalysis used data from 73 dogs in that report and added data from 26 more dogs from four other reports9,22,24,37 with RLN metastasis and re-analysed the effect of lymphadenectomy using a Kaplan-Meir survival curve. The finding that survival was significantly longer in dogs undergoing lymphadenectomy in the present pooled analysis (637 with vs 247 days without lymphadenectomy) adds further support to the concept that lymphadenectomy confers a survival advantage for dogs with cMCT and RLN metastasis.A classification system for the evaluation of RLN metastasis in canine cMCT has been established and clinically validated.…”