Low-dose abdominal radiation for cats with intestinal lymphoma

Abstract

The goal of this prospective, single-arm pilot study was to assess tolerability and clinical benefit for cats with histologically confirmed lymphocytic lymphoma/chronic inflammatory enteropathy complex (FLL/CIE) treated with low-dose abdominal cavity radiation therapy (RT; 8 Gy total dose administered in four 2 Gy fractions). No cats received steroids or chemotherapy prior to RT. Fourteen cats were enrolled and 13 completed the study. Eight cats had enteropathy-associated T cell lymphoma type II (FLL), and 6 cats had CIE (lymphoplasmacytic enteritis, 3 with concurrent eosinophilic enteritis). Nine of 13 cats (69%) had transient worsening of GI signs in the 1-3 weeks after RT, presumed secondary to RT and/or stress of travel/anaesthesia. Eight were managed as outpatients and one cat died after being syringe fed by the owner. Nine of the 12 remaining cats (75%; N = 6 with FLL and N = 3 with CIE) had a clinical benefit to treatment (resolution or improvement of GI signs as defined by owner surveys and body weight) that was sustained for > 340 days. Three cats experienced presumed or confirmed disease progression at 341, 465 and 449 days after RT and were treated with steroids. Six cats remained asymptomatic (N = 5) or stable (N = 1) at a median of 635 days after RT (range, 447-1014 days). Low-dose abdominal cavity RT could be considered for cats that cannot tolerate steroids and/or for owners that cannot pill cats routinely. Further optimisation of the protocol and use of RT as a rescue treatment for cats that fail traditional therapies are considerations for further study.