What are Lung Tumors?
Lung tumors are relatively rare in dogs, accounting for only 1% of all cancers diagnosed. The average age at diagnosis is 10 years with no sex or breed predilection. Metastatic cancer to the lungs is much more common than primary lung cancer. Lung tumors have moderate to high potential for metastasis (spreading). Metastasis usually affects the lung lobes, lymph nodes, pleura (lining of the chest cavity), bones and brain.
How are lung tumors diagnosed?
Most dogs with lung tumors present with coughing, exercise intolerance or other respiratory signs. Occassionally, patients will present for more vague, non-specific signs such as loss of appetite, weight loss or lethargy. The following diagnostics are recommended:
- Chest radiographs
- Ultrasound guided aspirate or biopsy
- Abdominal ultrasound
A CT scan is often proposed to better evaluate for secondary lung metastases or feasibility of surgical removal.
Routine blood work is helpful in evaluation of your pet’s overall health prior to surgery.
What is the treatment?
Surgery is the mainstay of treatment for dogs with lung carcinoma, provided no metastatic lesions are observed in other lung lobes. Dogs generally tolerate this surgery well and are discharged soon after the procedure. Chemotherapy may be recommended depending on the grade, size and presence of the tumor in lymphatics and/or blood vessels.
Chemotherapy is often recommended for high grade tumors, large tumors or tumors that show evidence of lymphatic or vascular invasion. Little information has been published on the efficacy of chemotherapy for dogs with primary lung carcinomas. Chemotherapy alone, without surgical removal of the mass, does not often yield significant decrease in the size of the mass or significant improvement in survival time.
What is the prognosis?
For dogs with small, low grade (well differentiated) tumors without lymph node involvement, the average survival time is 16 months or longer with surgery alone.
Dogs with high grade (poorly differentiated) tumors with lymph node involvement have an average survival of three months, even with surgery. Because many patients with high grade tumors will ultimately develop metastatic disease following surgery, chemotherapy is commonly recommended.