A feasibility study of low-dose total body irradiation for relapsed canine lymphoma.

Seven client owned dogs with confirmed relapsed lymphoma were enrolled in a prospective feasibility study investigating the effects of low-dose total body irradiation (LDTBI) delivered in a single 1 Gy fraction. LDTBI for relapsed lymphoma was safe and well tolerated. The only major side-effect of LDTBI was asymptomatic thrombocytopenia in all dogs. The median platelet nadir was 17,000/microL (range 4000-89,000), which occurred a median of 10 days (range 8-30) post irradiation. Three dogs had short-term partial responses, two stable disease and two progressive disease (PD). Six dogs were euthanatized for PD, and one dog died while in partial remission. No dogs had clinical complications. Survival analysis was not performed, because the study design did not allow for evaluation of survival time. Larger studies incorporating LDTBI in the induction/consolidation phase of treatment need to be performed to determine the therapeutic efficacy of LDTBI.

Radiation therapy for long-term control of odontogenic tumours and epulis in three cats.

Orthovoltage radiation was used to treat odontogenic tumours in three cats following incomplete surgical resection. Cats received a total radiation dose of 48-52 Gy over a period of 26-29 days. Acute toxicities were mild, consisting of hair loss within the radiation field in all cats, and mild mucositis in one cat. All cats had long-term (>35 months) control of their tumour, and two cats are still alive without recurrence of tumour 60 and 39 months, respectively, after completing treatment. Radiation therapy should be considered to be an adjuvant to incomplete surgery in cats with odontogenic neoplasms or epulides.

Radiotherapy of incompletely resected, moderately differentiated mast cell tumors in the dog: 37 cases (1989-1993).

Thirty-seven dogs with moderately differentiated, cutaneous mast cell tumors had incomplete surgical excisions as determined by histopathology, but no gross evidence of tumor. All dogs were irradiated to a total dose of between 46.2 and 48.0 Gy using either an orthovoltage source (n = 20) or a linear accelerator (megavoltage) (n = 17). Radiation was delivered to an area bordered by margins of 3 cm or greater around the surgical scar. The mast cell tumors had not recurred in 97% of dogs by one year after radiation therapy and had not recurred in 93% of dogs by three years after radiation. Both orthovoltage and megavoltage radiation provide excellent local control of moderately differentiated mast cell tumors in dogs.

Preoperative measurement of canine primary bone tumors, using radiography and bone scintigraphy.

Specimens of 20 canine primary bone tumors (18 osteosarcoma, 2 fibrosarcoma) were examined to compare the maximal axial length of gross tumor with the length of the lesion seen on preoperative radiographs and 99mTc methylene diphosphonate bone scintigraphic images. Radiographs defined the length of the tumor to within +/- 10% of the gross measurement for 6 (30%), underestimated it for 12 (60%), and overestimated it for 2 (10%) specimens. Bone scintigraphy defined tumor length within +/- 10% for 8 (40%), underestimated it for 1 (5%), and overestimated it for the remaining 11 (55%) specimens. Use of radiographic evaluation alone could result in underestimation of the diaphyseal extent of a primary bone tumor, with risk of incomplete resection. Bone scan images tend to overestimate tumor length and, therefore, may provide safer resection guidelines.