My greyhound Nina (9.5 now) is diagnosed with osteosarcoma today. Here is the timeline:
Feb 22nd: we noticed a very small lump near her right front ribs.
Feb 25th: our local vet did FNA and sent to the lab. Right side X-ray showed nothing on ribs chest or spine. By this time, the lump has grown much bigger than 22nd.
Mar 1st: the path report came back suggesting "malignant tumour" with no definitive type. It mentioned the possibilities of rhabdomyo-sarcoma, pleomorphic sarcoma, histiocytic sarcoma, adnexal clear cell carcinoma, and amelanotic melanoma.
Mar 7th: we went to TVEH for an oncologist appointment and a biopsy was done on the same day. CT was not done together due to scheduling problems.
Mar 10th: the oncologist called and told us the biopsy result showed as osteosarcoma.
Here is some of the report:
MICROSCOPIC INTERPRETATION: Osteosarcoma , osteoblastic, productive | Mitotic count: Greater than 30 per 2.4 mm2 (equivalent to ten 400x HPF). | Margins: Punch - n/a | Lymphatic/vascular invasion: Not observed
COMMENTS: Histopathologic evaluation revealed an osteosarcoma. Based on the history and radiographs this is suspected to be arising from the sternum (bone) as opposed to the extraskeletal; however, please correlate with the clinical picture. Osteosarcoma (OSA) arising within bones (central or medullary origin) accounts for up to 85% of malignant primary bone tumors in dogs. In general, canine OSA is a rapidly progressive neoplasm, with early mortality. The mean age of development is 7.5 to 8 years, but the age range is broad, and animals less than 2 years of age are sometimes affected. Dogs of giant breeds generally develop OSA at a younger age than dogs of smaller breeds. Between 20 and 25% of canine OSA develop from bones of the axial skeleton. Of these, approximately 50% develop on the head and 50% on the ribs, vertebrae, and pelvis. Osteosarcoma is often locally destructive and can be accompanied by pathologic fracture of the affected bone. For most axial OSA sites, difficulty of complete surgical excision complicates control of local disease. Metastasis is common, typically hematogenous, and arises early in the course of disease. The lung is the most common site of metastasis, but spread to lymph nodes, brain, other skeletal sites, and the skin/subcutis also occurs. Survival times for axial OSA are only marginally better than those for appendicular OSA, at 20 to 22 weeks. OSA of the maxilla/mandible may have a better prognosis, and relatively lower rates of metastasis. Improved survival times are reported with adjuvant chemotherapy in conjunction with adequate local excision.
And here is the discussion with our oncologist:
· Histopathology confirmed the diagnosis osteosarcoma, which is an aggressive cancer with high metastatic rate (75-100%). Because of the high risk of metastasis, complete staging tests such as thoracic radiograhs/CT scan and abdominal ultrasound/CT scan are recommended to confirm her tumour stage, especially if surgery or radiation therapy is elected.
· If lack of visible cancer metastasis is confirmed on the staging tests, surgical resection would extend her prognosis. Due to the location, size and fixed texture of her tumour, a thoracic CT scan is required for surgical planning. Though CT scan is necessary to confirm, it is most likely that extensive resection of parts of the sternal bone and associated ribs will be required. To treat the metastatic potential, adjuvant chemotherapy with carboplatin (intravenous every 3 weeks for 4 treatments) will be also recommended after surgery.
· In case metastasis is seen or surgery is not elected, palliative therapy such as palliative radiation therapy, chemotherapy, and oral supportive medications are another option. For radiation therapy, Nina needs to be referred to University of Guelph. Their typical protocol includes weekly therapy for 2-4 treatments under general anesthesia. Radiation therapy will be most effective palliative option to target the primary tumour on her chest. Alternative approach is to try a systemic palliative chemotherapy with carboplatin. · Unfortunately the prognosis of dogs with osteosarcoma on axial bones (i.e. ribs, spines) is poor. With local therapy alone such as radiation or surgery, reported median survival time is 3-4 months. When chemotherapy is added, the survival time can reportedly extend to 6-9 months, but majority of patients still develop systemic metastatic disease eventually.
Sorry for such a long post. If anyone has any experience or advice, we would really appreciate. Thanks!
