Immunostaining for VEGF and Decorin Predicts Poor Survival and Recurrence in Canine Soft Tissue Sarcoma

SIMPLE SUMMARY: Soft tissue sarcomas are one of the most common malignant tumours affecting the dog. Surgical removal is curative for the majority of patients, but local recurrence can develop in almost 20% of patients. Local recurrence is the most common reason for euthanasia, and a significantly shorter survival time. A recurrent tumour most likely arises from isolated tumour cells that remain in the wound bed following removal of all of the visible tumour. This study seeks to identify whether the presence of two proteins—vascular endothelial growth factor (VEGF) and decorin—within the tumour may assist with prediction of tumour recurrence. Both proteins are known to play important roles in enabling development of new blood supply to a developing tumour. It was hypothesised that if the original tumour contained proportions of these proteins known to be important for vascular development, this may provide residual cancer cells with a more enhanced ability to recrudesce into a visible recurrence. This study showed that recurrence following surgery was more likely if the tumour had a high level of staining for VEGF and/or did not stain for decorin. This study supports the hypothesis, but further investigation is required to validate this finding. ABSTRACT: The aim of this study was to investigate whether using immunohistochemistry to detect the angiogenic proteins vascular endothelial growth factor (VEGF) and decorin can help predict the risk of local recurrence of, or death from, canine soft tissue sarcoma (STS). VEGF and decorin were detected using validated immunohistochemical methods on 100 formalin-fixed paraffin-embedded samples of canine STS. The tumours had been resected previously, with clinical outcome determined by questionnaire. Each slide was assessed by light microscopy and the pattern of immunostaining with VEGF and decorin determined. Patterns of immunostaining were then analysed to detect associations with outcome measures of local recurrence and tumour-related death. High VEGF immunostaining was significantly (p < 0.001) associated with both increased local recurrence and reduced survival time. The distribution of decorin immunostaining within the tumour was significantly associated with survival time (p = 0.04) and local tumour recurrence (p = 0.02). When VEGF and decorin scores were combined, STS with both high VEGF and low decorin immunostaining were more likely to recur or cause patient death (p < 0.001). The results of this study suggest that immunostaining of VEGF and decorin may help predict the risk of local recurrence of canine STS.