Stereotactic body radiation therapy in the treatment of multiple primary lung cancers.

BACKGROUND AND
PURPOSE: Patients with multiple primary lung cancers (MPLC) present a therapeutic dilemma, particularly when they are at high risk for surgical resection. We evaluated the role of stereotactic body radiation therapy (SBRT) in the treatment of MPLC.
MATERIALS AND METHODS: A prospective thoracic SBRT registry was explored for patients with either synchronous or metachronous MPLC treated with SBRT for one or both of their tumors. Sixty-three patients were identified and clinical data were analyzed.
RESULTS: Fifteen patients had synchronous lesions and 48 patients had metachronous lesions. Seventy-six lesions were treated with SBRT. Median follow-up was 24 months for living patients. Median progression-free survival (PFS) and overall survival (OS) for the entire cohort was 15.5 and 20 months, respectively. Patients with metachronous MPLC had a significantly higher 2 year PFS (53.3% vs. 0%, p=0.0466) compared to patients with synchronous MPLC. Likewise, 2 year OS was also superior for patients with metachronous versus synchronous MPLC (68.1% vs. 27.5%, p=0.0014). Six tumors (7.9%) recurred within the radiation field. There were no grade ≥3 toxicities.
CONCLUSIONS: SBRT for patients with MPLC appears to be a safe and effective local treatment alternative to surgery, particularly for medically inoperable patients. Patients with metachronous MPLC have encouraging survival rates, and thus local therapy appears justified. However, patients with synchronous MPLC have poor OS and PFS despite having excellent local control, and thus the utility of local therapy in this population requires further study.