Dear OncoLink "Ask the Experts,"
My female lab (9 yrs. old) was diagnosed with a hemangiopericytoma this past February. Two days prior to the surgery, the vet took a chest x-ray, which identified two small (golf ball size) masses/tumors in separate lobes of the dog's lungs. The vet indicated that given the way the tumors presented they might in fact be primary versus metastasized from the hemangiopericytoma, which we understand would be a rare occurrence.
My questions are as follows:
Lili Duda, VMD, Editor of the OncoLink Veterinary Oncology Section, responds:
It is impossible to tell on chest X-rays alone whether a mass in the lungs are either primary lung cancer, or metastasis from another cancer elsewhere on the body. Hemangiopericytomas have been reported to metastasize in about 10-20% of cases, so it is quite possible that these masses are spread from the primary hemangiopericytoma. Primary lung tumors are very uncommon in dogs as compared to people. The mass is usually solitary, but can spread to other lung lobes and lymph nodes as well. Treatment options are limited and depend in part on whether the lung masses are primary (in which case surgical removal is a treatment option if there is no lymph node involvement), or metastatic (in which case palliative systemic chemotherapy is a potential treatment). In addition, it is possible that the tumor on the leg will cause symptoms before the lung masses will cause any symptoms.
While intralesional chemotherapy is not considered a standard treatment option for low grade soft tissue sarcomas, it has been used by some oncologists for cases in which conventional treatment such as radiation therapy or limb amputation has either failed or is not an option. Systemic palliative chemotherapy, as mentioned earlier, is an option, as is palliative radiation therapy. In general, multiple surgeries to remove a localized soft tissue sarcoma are not recommended, as the risks and potential complications of the surgery tend to outweigh the benefits.
Palliative treatment options should be considered whenever more definitive treatment options are either unlikely to be effective or are declined for other reasons. Palliation involves treating whatever is causing symptoms that decrease quality of life. Large primary tumors often have associated infection and inflammation, which are treated with antibiotics and anti-inflammatory (such as prednisone or piroxicam).