Feline Injection-Site Sarcoma Treated with Surgery,Orthovoltage Radiotherapy,and Electrochemotherapy. A Retrospective Series of 72 Cases

Abstract

Introduction:

Feline injection-site sarcoma (FISS) can arise from various agents that induce inflammation in the tissue, such as the injection of vaccines, antibiotics, anti-inflammatories, or even sutures.

Patients and Methods:

In this retrospective study, 72 cats with FISS grade 1 to 3 located in the spine or costo-abdominal area were included. They were separated into two categories: (A) patients treated with surgery with clean margins alone, surgery plus orthovoltage radiotherapy, and surgery plus electrochemotherapy. And category (B), patients treated with surgery without clean margins, surgery plus orthovoltage radiotherapy, surgery plus electrochemotherapy, and surgery plus orthovoltage radiotherapy and electrochemotherapy. In all cases, surgery with adequate margins was intended. In the cases that the histopathology of the resected tissue showed suboptimal margins, orthovoltage radiotherapy was added after wound healing. In the cases where surgery was performed with insufficient margins, electrochemotherapy was performed in the resection bed during surgery, following the veterinary guidelines for electrochemotherapy.

Results and conclusion:

Results showed that patients with clean margin resection who underwent surgery alone had no statistically significant improvement in overall survival (OS) or disease-free survival (DFS) when adding orthovoltage radiotherapy or electrochemotherapy.

 Among patients who underwent surgery without clear margins, those treated with surgery alone had a statistically significant shorter DFS and OS. In contrast, patients who received adjuvant orthovoltage radiotherapy, electrochemotherapy, or a combination of both demonstrated improved DFS and OS. However, no statistically significant differences were observed between the various adjuvant treatment modalities.

 In conclusion, when FISS cannot be resected without clean margins, the addition of orthovoltage radiotherapy or electrochemotherapy can provide equal benefits regarding the improvement of DFS and OS times.