Palliative Radiotherapy of Appendicular Osteosarcoma in 95 Dogs

Abstract

Ninety-five dogs with either a presumptive (n = 24) or biopsy confirmed diagnosis (n = 71) of osteosarcoma received palliative radiotherapy using 60Co photons. Parallel opposed beams were used with each dog receiving either 10 Gy on days 0, 7 and 21 (n = 58) or 8 Gy on days 0 and 7 (n = 37). The 8 Gy fractionation scheme was given with the intent of retreating upon relapse from pain relief. Only 9 of 37 (24%) dogs in the 8 Gy group returned for retreatment. Forty-seven of the 95 dogs (49%) received concurrent or sequential chemotherapy. Seventy of the 95 dogs (74%) experienced pain relief following treatment. In dogs experiencing pain relief the median duration of response was 73 days. Numerous clinical variables were evaluated as predictors of response. The only variable significantly related to achieving a response was the use of chemotherapy. The following variables were significantly related to the duration of response: extent of bone lysis, chemotherapy use, length of bone involved and tumor site (humerus). In a multivariate analysis (n = 73 dogs), after adjusting for chemotherapy use, extent of bone involvement (p = 0.01) and tumor site (p = 0.02) retained statistical significance, while degree of bone lysis did not (p = 0.11). No difference in response incidence or duration was found between 3 fractions of 10 Gy vs. 2 fractions of 8 Gy. Administration of a low initial dose with the intent of retreatment was not a successful strategy.

Evaluation of outcome and prognostic factors for dogs living greater than one year after diagnosis of osteosarcoma: 90 cases (1997–2008)

“…Radiotherapy is commonly used as a treatment for metastatic bone disease, especially in patients that have a previous amputation, and approximately 75% to 92% of dogs with appendicular osteosarcoma will have apparent pain relief from palliative radiotherapy to bone lesions. 21,26 In the present study, palliative radiotherapy of metastatic bone lesions did not prolong survival times after > 1 year. Information concerning pain relief provided by the radiotherapy was not able to be obtained from the medical records.…”

Treatment of appendicular osteosarcoma in a horse

“…Radiation therapy may be used to relieve pain and retard growth rate (McEntee et al . 1993; Ramirez et al . 1999) but was impractical for the horse in this report.…”

Relative biological effectiveness in canine osteosarcoma cells irradiated with accelerated charged particles

“…Alternative treatments to suppress tumor growth and alleviate the pain of the primary tumor would have significant clinical relevance in these cases. Coarsely fractionated, or 'palliative' radiation therapy using several fractioned doses (for example, 8-10 Gy per fraction) may be used for palliation of pain, but is not able to achieve local tumor control (3)(4)(5). High dose per fraction radiation therapy has been described as a method for local tumor control using stereotactic radiosurgery, particularly when combined with chemotherapy (5,6).…”