Lung Cancers

Although tumors arising from the lung are uncommon in dogs, chronic coughing and an irregular breathing pattern may indicate the presence of lung cancer. These tumors are almost always malignant, with the most common type being adenocarcinoma. The dog's living environment is an important factor to the occurrence of lung tumors. Just as with humans, secondhand smoke in the pet's home due to a smoking owner correlates with an increased incidence of lung cancer in dogs.

Canine lung cancer is aggressive and metastasizes to the regional lymph nodes and tissues of the thorax. Chest radiographs are the most common pre-operative diagnostic tool. Most commonly, a large solitary mass is visible in the lung fields. These may partially obstruct airflow, leading to breathing symptoms. The diagnosis is confirmed at the time of surgery with an excisional biopsy. The mean survival time of dogs with lung cancer is 11 months after diagnosis.

Treatment of Lung Cancers

Surgical excision of the tumor is first step used to treat canine lung cancer. The prognosis depends on the size of the tumor, and whether it has metastasized to lymph nodes and other tissues. With small tumors that have not metastasized, surgical excision is potentially curative. Radiation therapy may still be recommended after surgery in order to limit recurrence. Chemotherapy may be used to treat the animal if metastases are detected.

Because lung cancers are highly dependent upon angiogenesis for their growth and spread, antiangiogenic therapy may be useful for this condition. Studies of lung cancer in animals have clearly shown that the greater the number of microvessels within the lung cancer, the worse the prognosis. Angiogenesis inhibition has slowed lung cancer growth significantly in animals. Researchers have shown that a drug mimicking the natural angiogenesis inhibitor thrombospondin-1 can inhibit lung cancer in animals. A similar drug, called ABT-510, is now in veterinary trials for canine cancer. In human patients, other antiangiogenic drugs have been used to treat lung cancer, including Avastin, Neovastat, TNP-470, squalamine, and endostatin.