Successful Treatment of Vertebral Osteosarcoma in a Cat Using Marginal Surgical Excision and Chemotherapy

Abstract

A three-year-old male neutered Norwegian Forest cat was referred for bilateral ambulatory paraparesis and spinal pain. On magnetic resonance imaging (MRI), a mass involving the right epaxial muscles with vertebral canal invasion and causing marked extradural spinal cord compression was identified. At surgery, the mass was debulked and a right hemilaminectomy was performed. Histopathology was diagnostic of fibroblastic osteosarcoma. Residual osteolytic lesions of the osteosarcoma were present at the level of the spinous process of the second lumbar vertebra. Four cycles of adjuvant doxorubicin chemotherapy were administered followed by oral toceranib phosphate. Neurological signs improved gradually over weeks to months and the lesion in the spinous process was no longer visible on radiographs. At one year from diagnosis, an MRI of the T3-L3 (3rd thoracic vertebra to the 3rd lumbar vertebra) spinal region and a whole-body computer tomography (CT) scan found no evidence of the osteosarcoma in the spine or of any metastasis. All medications were stopped and, at the time of writing 16 months later, the patient is neurologically normal with no signs of cancer recurrence. This is the first case report documenting the complete resolution of vertebral osteosarcoma lesions after treatment with doxorubicin followed by toceranib phosphate. The treatment also prevented tumor recurrence and was associated with an exceptionally long-term survival time.

Vertebral Osteosarcoma in Two Cats—Diagnosis, Treatment, and Outcome

“…This case report highlights the possibility of good outcomes after surgical treatment of FVO supplemented with post-surgical chemotherapy. Such positive outcomes have been documented in a few cases of FVO before [7][8][9][10]. Along with those reports, our case report provides further support for the consideration of such treatments for FVO.…”

“…Surgical treatment options of FVO include but are not limited to cytoreduction, extirpation, debulking, and vertebral replacement [1,2,[6][7][8][9][10]. Depending on the exact parts of the vertebra involved, an approach commonly used is a dorsal approach for a dorsal laminectomy, with decompression of the spinal cord being achieved by the removal of the mass.…”

“…Compared with its canine counterpart, feline osteosarcoma (FO) is infrequently diagnosed in veterinary medicine [1][2][3][4][5][6]. FO affecting the axial skeleton, or feline vertebral osteosarcoma (FVO), is only described in detail in a few veterinary publications [7][8][9][10][11]. These publications have provided important information regarding possible outcomes of surgical and medical treatment.…”

“…Based on the literature, aggressive surgical treatment seems to be the most effective treatment for all types of FO, irrespective of additional treatment such as chemotherapy [1][2][3][4][5][6][7][8][9][10][11]. Mean survival times are reported to be shorter for FVO compared to appendicular FO [1,2].…”

“…Local recurrence is reported after cytoreductive surgical treatment [11]. Still, there are recent case reports that document favorable long-term outcomes for the surgical treatment (with additional chemotherapy) of FVO [7][8][9][10].…”