Evaluation of radiotherapy alone or in combination with doxorubicin chemotherapy for the treatment of cats with incompletely excised soft tissue sarcomas: 71 cases (1989-1999).

OBJECTIVE: To determine whether the addition of doxorubicin chemotherapy affected the outcome of cats with incompletely excised, nonvisceral soft tissue sarcomas undergoing postoperative radiotherapy. DESIGN: Retrospective case series. ANIMALS: 71 cats. PROCEDURES: Medical records were reviewed for clinically relevant data on cats that underwent postoperative radiotherapy for treatment of incompletely excised soft tissue sarcomas with or without concurrent doxorubicin chemotherapy. Radiotherapy was performed on an alternate-day schedule, with a total dose of 58.8 to 63 Gy delivered in 21 fractions. Doxorubicin was administered every 21 days for 3 to 5 cycles. Follow-up information was obtained by means of physical examination or through telephone conversations with refer-ring veterinarians or owners. RESULTS: Median disease-free interval with concurrent radiotherapy and doxorubicin chemotherapy (15.4 months; range, 2.4 to 44.9 months) was significantly longer than median disease-free interval with radiotherapy alone (5.7 months; range, 1.0 to 50.8 months). However, survival time was not significantly different between groups. CONCLUSION AND CLINICAL RELEVANCE: Results suggested that doxorubicin chemotherapy may play a role in extending the disease-free interval in cats undergoing radiotherapy for treatment of incompletely excised soft tissue sarcomas.

Hematologic changes associated with half-body irradiation in dogs with lymphoma.

BACKGROUND: Reports describe the technique and efficacy of half-body irradiation (HBI) of dogs with lymphoma, but few describe the distinctive toxicoses associated with the combination of HBI and chemotherapy. HYPOTHESIS: HBI would transiently affect myelocytic and erythroid variables as assessed by serial analysis of complete blood counts. ANIMALS: Twenty-nine dogs with lymphoma treated with HBI during 2002 and 2003. METHODS: A retrospective study of medical records of 29 dogs was performed. Two HBI protocols were used, resulting in delivery of either 6 Gy or 8 Gy to each half of the body, 1 month apart. Dogs received chemotherapy before, during, or after irradiation, or at multiple times. Serial hematology was available for all dogs. Data were analyzed between collection periods by analysis of variance (ANOVA) RESULTS: The mean granulocyte count significantly (P < .01) decreased from 10,017 cells/microL (data range 3,001-20,170 cells/ microL) before the first radiation treatment to 3,250 cells/microL (820-4,400 cells/microL) at week 5 (P < .01). Three weeks after this nadir, the mean increased to 10,150 cells/microL (900-26,700 cells/microL). The hematocrit did not change (36-38%). Thrombocytopenia (<100,000/microL) occurred in 10 dogs. Two dogs died because of complications associated with thrombocytopenia. No significant difference in toxicity was found between the 6 Gy and 8 Gy group. CONCLUSIONS AND CLINICAL IMPORTANCE: HBI was myelosuppressive but effects were short term and resolved in 22 of 24 dogs. Further studies are needed to elucidate the safety and role of HBI in the treatment of dogs with lymphoma.

Efficacy of radiation therapy for incompletely resected grade-III mast cell tumors in dogs: 31 cases (1987-1998).

OBJECTIVE: To determine the efficacy (durations of remission and survival) of an alternating-day radiation protocol for incompletely excised histologic grade-III solitary mast cell tumors (MCTs) in dogs. DESIGN: Retrospective study. ANIMALS: 31 dogs. PROCEDURE: Radiation (52 Gy in an 18-fraction alternating-day protocol) was delivered to an area bordered by margins > or = 3 cm around the surgical scar and to the associated local-regional lymph nodes. Dogs were not given chemotherapeutic agents concurrently or after radiation. Information on signalment, duration of remission, and survival time was obtained from medical records. RESULTS: Median and mean durations of remission were 27.7 and 17.0 months, respectively (range, 1 to 47 months). Median and mean durations of survival were 28 and 20 months, respectively (range, 3 to 52 months). Dogs with tumors located on the skin of the pinna, perineum, and prepuce had a median duration of remission greater than dogs with tumors located at other sites (27.7 and 14.4 months, respectively). Dogs with tumors < or = 3 cm in maximum diameter before surgery survived longer than dogs with tumors > 3 cm (31 and 24 months, respectively). The remission rate was 65% and survival rate was 71% at 1 year after treatment. Sixteen dogs that were euthanatized had complications associated with local-regional tumor progression. Systemic metastases to liver, spleen, intestine, and bone marrow were detected in 1 dog. CONCLUSIONS AND CLINICAL RELEVANCE: Without further treatment, incompletely excised grade-III mast cell tumors have high local-regional recurrence; local-regional treatment with radiation may effectively be used to manage many such tumors.

Treatment of dogs with oral melanoma by hypofractionated radiation therapy and platinum-based chemotherapy (1987-1997).

This retrospective study in 39 dogs with incompletely resected oral melanoma examined the efficacy of hypofractionated radiation therapy and platinum-containing chemotherapy. All dogs were completely staged, with the majority of dogs classified as stage 1. Dogs received 6 weekly fractions of 6-gray (Gy) megavoltage irradiation with a cobalt-60 unit or a 4-MeV (megaelectron volts) linear accelerator. Dogs received cisplatin (10-30 mg/m2 IV) or carboplatin (90 mg/m2 IV) chemotherapy 60 minutes before radiation delivery. Durations of local control, metastasis-free survival time, and overall survival time were recorded. By the Kaplan-Meier method, 15% of the dogs had local recurrence within a median time of 139 days. Fifty-one percent of the dogs developed metastatic disease within a median time of 311 days (range, 24-2, 163 days). Median survival time for all 39 dogs was 363 days. The combined use of chemotherapy and radiation therapy in this protocol provided local control consistent with previous studies. Low-dose chemotherapy was used with the intent of enhancing radiation therapy for the local control of an incompletely excised tumor. Survival times were longer than previously reported for dogs with oral malignant melanoma. Additional studies are required to determine whether these results were due to the effects of chemotherapy on microscopic disease or the enhanced local control provided by chemoradiation therapy.

Effects of plasmid-mediated growth hormone-releasing hormone in severely debilitated dogs with cancer.

Cachexia is a common manifestation of late stage malignancy and is characterized by anemia, anorexia, muscle wasting, loss of adipose tissue, and fatigue. Although cachexia is disabling and can diminish the life expectancy of cancer patients, there are still no effective therapies for this condition. We have examined the feasibility of using a myogenic plasmid to express growth hormone-releasing hormone (GHRH) in severely debilitated companion dogs with naturally occurring tumors. At a median of 16 days after intramuscular delivery of the plasmid, serum concentrations of insulin-like growth factor I (IGF-I), a measure of GHRH activity, were increased in 12 of 16 dogs (P < 0.01). These increases ranged from 21 to 120% (median, 49%) of the pretreatment values and were generally sustained or higher on the final evaluation. Anemia resolved posttreatment, as indicated by significant increases in mean red blood cell count, hematocrit, and hemoglobin concentrations, and there was also a significant rise in the percentage of circulating lymphocytes. Treated dogs maintained their weights over the 56-day study and did not show any adverse effects from the GHRH gene transfer. We conclude that intramuscular injection of a GHRH-expressing plasmid is both safe and capable of stimulating the release of growth hormone and IGF-I in large animals. The observed anabolic responses to a single dose of this therapy might be beneficial in patients with cancer-associated anemia and cachexia.