EFFECT OF X-IRRADIATION ON MASTOCYTOMAS IN DOGS

Eighteen dogs with mastocytoma were given X-irradiation to live tumor cells. Microscopic examination was performed prior to X-irradiation of the tumor and at varying time intervals after treatment (to ascertain effectiveness of treatment). Inadequate field size resulted in marginal recurrences in 3 dogs, and coarse dose fractionation caused necrosis. Necropsy was performed on 9 dogs. Fractionation, with a total dose of 700 to 3,000 R administered during a period of 7 to 14 days was found to be a curative dose. Marginal recurrences required special consideration in selection of field size to decrease recurrence. Further studies are essential to establish a minimum time-dose schedule for canine mastocytoma.