Palliative efficacy and local control of conventional radiotherapy for lung metastases

The lung is a common site of metastasis, and conventionally fractionated radiotherapy (CFRT) is commonly used to treat such metastases, usually to palliate symptoms. However, no data exists to quantify palliation or local control (LC) of CFRT for secondary lung tumors. We aimed to describe the palliative effect of CFRT for lung metastases at our institution, and compare its LC with that of stereotactic body radiation therapy (SBRT).

182 patients received 190 courses of RT for lung metastases (99 CFRT, 91 SBRT). We characterized the proportion of CFRT patients who experienced palliation, the durability of palliative effect, and cumulative incidence of local failure (LF) using competing-risks regression. We also performed an exploratory comparison of LF between CFRT and SBRT.

In CFRT patients, cumulative incidence of LF at 6 months and 1 year was 32% and 43%, respectively. Rate of initial palliation was 74%. Palliation rates for the most common indications were as follows: hemoptysis 86% (25/29), cough 71% (12/17), airway obstruction 66% (25/38), pain 64% (7/11). Of patients who reported palliation, 6-month and 1-year cumulative incidence of symptom recurrence was 52% and 65%, respectively. In SBRT patients, LF at 6 months and 1 year was 5.8% and 19.5%, respectively.

CFRT effectively alleviates a variety of symptoms in lung metastases, supporting its continued use in palliation of metastatic disease. However, subsequent local progression and symptom relapse are common with CFRT. As SBRT is associated with higher rates of LC, this may be preferred in eligible patients with more favorable prognosis.