Samarium Sm 153 lexidronam is a radiopharmaceutical with demonstrated antitumor properties and efficacy for pain palliation in the treatment of skeletal neoplasia. Palliative and even curative effects have previously been demonstrated in dogs receiving 153Sm-EDTMP for the treatment of skeletal neoplasia, including primary tumors and secondary metastatic disease.1,2 Although limited, these previous clinical studies1,2 provide support for 153Sm-EDTMP as a therapeutic option for patients with primary bone tumors that are not candidates for other established treatments. In veterinary medicine, 153Sm-EDTMP has primarily been used in the treatment of appendicular tumors; however, the bone-targeting radiopharmaceutical presents an attractive alternative treatment for patients with inoperable bony tumors of the skull. A previous study1 of dogs examining the clinical response of bone tumors treated with 153Sm-EDTMP indicated a good response rate (response determined by functional improvement and radiographic involution of the lesion) in patients with tumors of the axial skeleton, heavily calcified or ossified lesions, tumors that had not broken through the cortex of the bone, and small metastatic lesions (diameter, < 2.0 cm). In the authors' clinical experience, many primary bony tumors of the skull, such as purely osteoproductive OAs of the calvarium, possess ≥ 1 of these tumor characteristics.
Various tumor types have been reported to affect the skull in dogs; the 2 most common primary bony tumors of the skull are MLO and OSA. Osteosarcoma is a primary malignant bone tumor commonly found in dogs, which affects the appendicular and axial skeleton. Osteosarcomas of the axial skeleton not only affect flat bones of the skull but also commonly affect the mandible and maxilla, nasal bone, pelvis, rib, and spine.3–8 Osteosarcoma originating from the axial skeleton accounts for approximately 25% of all OSAs diagnosed in dogs.3,6,9 It has been our clinical experience that OSA of the calvarium has a tendency to be purely osteoproductive, a feature of this tumor which was reported some years ago.10 Multilobular osteochondrosarcoma is a tumor composed of bone or partially to completely calcified tissue and is surrounded by mesenchymal tissue or stroma.11 Multilobular osteochondrosarcomas are slow growing, locally invasive, compressive tumors with a low overall metastatic rate.11–16
The purpose of study reported here was to evaluate 153Sm-EDTMP as a treatment for dogs with primary bony tumors of the skull, when surgical excision was not an option because of tumor location and in which the use of nuclear scintigraphy with 99mtechnetiummethylene diphosphonate tumor uptake17 suggested potential efficacy of this treatment.
Samarium Sm 153 lexidronam
Median survival time
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