Is stereotactic body radiation therapy effective for isolated lung metastasis following lung surgery?

The authors evaluated the outcomes of stereotactic body radiation therapy (SBRT; very precise radiation therapy) for isolated lung metastasis (cancer that has only spread to the lungs) arising after surgery for lung tumors.

Lung metastasis is one of the most common problems in cancer irrespective of the origin of the primary tumor. In most cases the cancer also spreads to other parts of the body. In certain cases the cancer only spreads to the lung (isolated lung metastasis (ILM)). Patients who undergo pulmonary lobectomy (removal of one of the lobes of lungs) for the treatment of lung cancer can later be affected with ILM. Although, there are some techniques available for surgical removal of ILM, these are mainly used for ILM from colorectal cancer, breast cancer and other type of cancer. Further surgery is rarely used for ILM after a previous pulmonary lobectomy.

SBRT has been recommended as one the few safe and effective techniques for patients with ILM after a previous lobectomy. In SBRT, the tumor receives a high-dose radiation while the surrounding normal cells receive a low dose. This allows curative treatment of the cancer, while sparing the surrounding tissues from injury. However, not much is known on the outcome of SBRT for ILM after pulmonary lobectomy. 

The authors aimed to analyze medical records of patients who were treated with SBRT for ILM following lobectomy.

This study examined 23 patients who were treated with SBRT for ILM. The cancer returned close to the original site (local recurrence) in 8.7% of patients after SBRT. The average overall survival was 21 months. The average progression-free survival (time following the treatment before the disease progressed; local recurrence or distant recurrence) was 10 months.  

A common side effect of SBRT was radiation-induced pneumonitis (inflammation of lungs), which led to coughing in 60.9% of patients and shortness of breath in 8.7% of patients. 5 patients (21.7%) had moderate pneumonitis and 3 patients (13.0 %) had severe pneumonitis. The severity of pneumonitis was related to the radiation dose of SBRT. Other treatment-related adverse events included chest-wall pain in 1 patient (4.3%) and acute esophagitis (inflammation in the food pipe) in 2 patients (8.7%).

The authors concluded that with careful monitoring of the radiation dose, SBRT could be a safe and an effective technique for the treatment of ILM following pulmonary lobectomy.

This study was limited by having a low number of patients (23). Therefore, further research is needed to ensure the accuracy of the results.