The utility of Microwave ablation therapy in the treatment of pulmonary metastases

The aim of this study was to evaluate the safety and efficacy of microwave ablation therapy on pulmonary metastases (cancer spread to the lungs) that cannot be removed surgically. The study showed that it can be an effective treatment method with a success rate depending on the tumor size.

Pulmonary metastases represent secondary tumors resulting from the spread of cancer cells to the lungs. They originate more frequently in primary cancers with a rich venous drainage system, like colorectal cancer (CRC). The primary goal of any type of treatment is to destroy all the cancerous cells, including a margin of normal tissue, while minimizing damage to the remaining lung tissue. Microwave ablation therapy involves guiding a probe via the blood vessels to the metastases and delivering microwave energy to destroy the tumor.

The present study was conducted between 2007 and 2010 on 80 patients with lung metastases. Patients included in the study had metastases that could not be removed surgically either due to other associated illnesses or to previous lung surgery for the same condition. Also, they had 5 or fewer lesions of less than 5 cm. They received computer tomography- guided percutaneous (performed through the skin) microwave ablation (removal with the help of microwaves) of lung metastases. Half of the patients had lung lesions that originated from a primary CRC.

Complete successful ablation was achieved in 73% of the lesions, especially in tumors that had a diameter of less than 3 cm. New metastases developed in 7.5% of the patients with CRC. The survival rate one year after the procedure was 91.3% and 75 % after two years.
 

In conclusion, the results of microwave ablation were primarily determined by the lesion size and location.  Success is more likely for lesions located at the periphery of the lung, preferably smaller than 3 cm. The ultimate goal of local ablation therapy is to prolong survival and allow adequate tumor control.

This procedure is an option only when the potential benefits are higher than the risks of complications. The study's limitations consisted of a relatively short follow-up period (24 months) and the non-randomized design – it did not compare two study groups, one receiving and one not receiving the procedure.