A 16-year old castrated male domestic shorthair cat was evaluated at a veterinary teaching hospital because of polyuria, polydipsia, and weight loss of 2 months’ duration.
Hematologic and biochemical examination results were within respective reference ranges except for moderately high pancreas-specific lipase concentration. Ultrasonographic and cytologic evaluation revealed a hepatic mass with findings consistent with mild cholestasis and inflammation and a pancreatic mass that was initially identified as a neuroendocrine tumor.
TREATMENT AND OUTCOME
The cat underwent additional CT assessment and stereotactic body radiation therapy (SBRT; 3 fractions of 8 Gy, administered every other day) for treatment of the pancreatic tumor. Follow-up ultrasonographic and CT examinations indicated a partial response to SBRT, with a maximum CT-measured size reduction from 3.6 × 4.8 × 4.0 cm at the time of treatment planning to 2.0 × 2.0 × 1.9 cm 8 months later. Increased pancreatic tumor size and signs of carcinomatosis were detected 15 months after SBRT treatment; the initial cytologic diagnosis was changed to exocrine pancreatic carcinoma on reevaluation of the slides by another veterinary pathologist. Carboplatin treatment was elected, and signs of carcinomatosis resolved. The cat was euthanized without further testing because of weakness 589 days after SBRT was started.
To the authors’ knowledge, this is the first report of SBRT for suspected exocrine pancreatic carcinoma in a cat. Further investigation is needed to determine optimal fractionation schedules for SBRT of pancreatic tumors and utility of SBRT of exocrine pancreatic carcinoma in cats. (J Am Vet Med Assoc 2021;259:184–189)
Objective—To evaluate outcomes of stereotactic body radiation therapy (SBRT) in cats with injection-site sarcomas (ISS) via assessment of local responses and recurrences, survival times, and complications.
Design—Retrospective case series.
Animals—11 cats with ISS.
Procedures—Medical records of cats that were treated with SBRT for ISS between June 2008 and July 2012 were reviewed; information on patient demographics (age, sex, and breed), oncological histories (including prior treatment and histologic grade), details of SBRT plans (tumor volume, treatment field sizes, and prescription), response to treatment (including toxicoses), progression-free intervals, and survival times were extracted.
Results—Acute radiation-associated toxicoses were infrequent and limited to mild, self-limiting dermatitis and colitis in 2 and 1 of the 11 cats, respectively. No late radiation-associated toxicoses were observed. The objective response rate was 8 of 11 cats; these patients either had a partial or complete response as determined on the basis of CT or physical examination findings. The median progression-free interval was 242 days, and the median overall survival time was 301 days; median follow-up time of censored subjects was 173 days.
Conclusions and Clinical Relevance—SBRT was completed in 3 to 5 days and was well tolerated when used to treat cats with ISS. Measurable tumor responses were achieved in most cats in this study. Stereotactic body radiation therapy provided a means for palliation of ISS; further investigation is required to determine whether SBRT is a valid treatment option for downstaging disease prior to definitive surgery.