Hypofractionated radiation therapy of brain masses in dogs: a retrospective analysis of survival of 83 cases (1991-1996).

There are few reports of radiation treatment for brain tumors in dogs, and the optimal treatment protocol has yet to be established. We completed a retrospective analysis of the survival times of a series of 83 dogs with intracranial masses that were treated by hypofractionated megavoltage radiation therapy. A total tumor dose of 38 Gray was given over 5 weeks as once weekly fractions via 3 perpendicular portals. The median survival time from the start of radiotherapy for the whole cohort was 43.7 weeks (range, 0.1-172 weeks). Extra-axial masses had a better survival time (49.7 weeks) than did other intracranial masses (intra-axial, 40.4 weeks; pituitary, 21.0 weeks). Delayed radiation toxicity was suspected as the cause of death or reason for euthanasia in 12 dogs. The hypofractionated radiation protocol resulted in survival times similar to those obtained using more conventional multifractionated regimens, and this protocol may be a useful, less intensive alternative treatment for brain tumors in dogs.