Canine Appendicular Osteosarcoma: Staging and Palliative Radiation Therapy

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Canine Appendicular Osteosarcoma: Staging and Palliative Radiation Therapy

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dc.contributor.advisor Boston, Sarah
dc.contributor.author Oblak, Michelle
dc.date 2012-06-22
dc.date.accessioned 2012-07-18T14:33:05Z
dc.date.available 2012-07-18T14:33:05Z
dc.date.issued 2012-07-18
dc.identifier.uri http://hdl.handle.net/10214/3802
dc.description.abstract This thesis is an investigation of diagnostic staging and palliative radiation therapy (RT) for appendicular osteosarcoma (OSA) in dogs. Osteosarcoma is a common, highly metastatic primary bone tumour of dogs. The purpose of the first study was to assess the utility of whole body computed tomography (CT) in evaluation of metastasis in dogs with primary appendicular OSA. The objectives were to determine the utility of whole body CT as a staging tool for dogs with appendicular OSA, compare the lesion detection rate of bone scintigraphy, long bone survey radiography and whole body CT in dogs with appendicular OSA and determine the prevalence of CT-detected lung metastasis in dogs with appendicular OSA that have normal thoracic radiographs. This was a prospective cross-sectional observational study involving fifteen dogs. Test modalities were assessed against a construct reference standard for detection of bone metastasis and thoracic radiographs negative for metastatic lesions were compared against thoracic CT. Bone scintigraphy identified 5 bone lesions in 4 dogs with 2 false positive and 2 false negative results. No lesions were identified on survey radiographs or CT during blinded assessment. CT was useful for further characterizing lesions identified by bone scintigraphy. Thoracic CT identified both definitive and equivocal lesions not visible radiographically. Four dogs had equivocal ground glass pulmonary lesions on CT; 3 of these lesions progressed to radiographically discrete nodules. Overall, bone scintigraphy was the only modality that identified metastatic bone lesions. Whole body CT did not appear to be useful as alternative to bone scintigraphy; however, it may have some utility as an adjunctive diagnostic modality. Thoracic CT identified pulmonary lesions that were not visible radiographically. Ground glass pulmonary lesions in dogs should be considered suspicious for metastasis and serially monitored. The purpose of the second study was to retrospectively assess factors affecting survival time in dogs undergoing palliative RT for appendicular OSA. Fifty dogs undergoing a palliative RT protocol for spontaneous primary appendicular bone tumours were included and divided into treatment groups based on treatments administered in addition to RT. Median survival times (MST) were longest for dogs receiving RT and chemotherapy (307 days; 95%CI= 279-831) and shortest in dogs receiving RT and pamidronate (69 days; 95%CI=47-112 days). The difference in MST between dogs who received pamidronate and those who did not in this population was statistically significant on univariate (p=0.039) and multivariate analysis (p=0.0015). The addition of chemotherapy into any protocol improved survival (p<0.001). Based on the findings in this study, chemotherapy should be recommended in addition to a palliative RT protocol to improve survival of dogs with primary appendicular bone tumours. When combined with RT +/- chemotherapy, pamidronate decreased MST. en_US
dc.description.sponsorship Ontario Veterinary College Pet Trust Fund en_US
dc.language.iso en en_US
dc.rights.uri http://creativecommons.org/licenses/by-nc-nd/2.5/ca/ *
dc.subject Canine en_US
dc.subject Cancer en_US
dc.subject Bone tumour en_US
dc.subject Osteosarcoma en_US
dc.subject Chemotherapy en_US
dc.subject Radiation therapy en_US
dc.subject Staging en_US
dc.subject Computed tomography en_US
dc.subject Bone scintigraphy en_US
dc.title Canine Appendicular Osteosarcoma: Staging and Palliative Radiation Therapy en_US
dc.type Thesis en_US
dc.degree.programme Clinical Studies en_US
dc.degree.name Doctor of Veterinary Science en_US
dc.degree.department Department of Clinical Studies en_US


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