The most effective therapy for feline injection site-associated sarcomas is aggressive surgery with wide margins. The most important prognostic factor for local recurrence and survival time is complete/clean surgical margins. Tumour size has been reported to influence survival after surgery. This is due to increased difficulty achieving complete/clean surgical margins as opposed to different biological behaviour.

 

The current guidelines for surgical removal at injection sites include removal if the mass

 - exists for more than 3 months after injection,

 - increases significantly in size within 4 weeks, or

 - is larger than 2 cm in diameter.

 

Histologically complete resection is reported for 95% of tumours with 5-cm lateral margins. Compared to one fascial layer for deep margins, surgical excision of two fascial layers for deep margins reduces the local tumour recurrence rate to 14% (from 39%). The risk of distant metastasis is low and develops in 20-21% of cats.

 

The overall median survival time is 901 days (2 years and 5 months). The median survival time for cats that developed distant metastasis was 388 days (1 year and 1 month) and 1528 days (5 years) for cats without metastasis.