Tumour Margins: A Veterinary Perspective

A clean tumor margin excision is one of the main goals of oncological surgeons. This is particularly true in veterinary oncology in which, contrary to what often occurs in human medicine, the use of neoadjuvant chemo- and/or radio-therapy in an attempt to decrease tumor size, thus potentially reducing surgical dose, are not routinely utilized. A few reports on neoadjuvant treatments are available in the veterinary literature. One of these reports refers to neoadjuvant prednisone for mast cell tumors (MCT),1 especially if localized in “difficult sites”, i.e. in which a complete excision is difficult. In this study tumor resection was performed according to a 3-cm lateral margin/one deep intact fascial plane rule, if feasible, with resection margins based on post-treatment mass size; if MCT was no longer identifiable (complete response), resection margin was just outside the grossly evident border of the mass prior to treatment.1 Other reports are about doxorubicin or epirubicin prior and after feline injection-site sarcomas (ISS) excision; however, no clear advantage of neoadjuvant chemotherapy has been demonstrated.2,3 Also neoadjuvant radiotherapy is not very popular in veterinary oncology because it is feared that further surgery may be associated with complications (necrosis, local infection, dehiscence, and ulceration); the same may occur if skin or mucosal flaps are used to cover areas previously irradiated in which complications have developed.4 Complications seem dose- (3 vs. 4 Gy for fraction) and site-related (head and neck would be characterized by a decreased severity of complications)4. Adjuvant radiation may also be sometimes a concern as a potential cause of complications if the surgical site derived from an aggressive resection has been covered with skin or mucosal flap; however, flaps that are part of a pre-planned therapy would be characterized by a better clinical outcome.  [...]