A second lung cancer is occasionally observed in patients who underwent surgical resection of the index lung cancer. The purpose of this study is to evaluate stereotactic body radiation therapy for second lung cancer.

METHODS: Fifty-one medically inoperable patients who underwent stereotactic body radiation therapy for second lung cancer were the subjects: 31 cases of multiple primary lung cancer and 20 of pulmonary metastasis from the index cancer. Clinical stage was T1a in 27 patients, T1b in 13 patients and T2a in 11 patients, and 70% of subjects had impaired respiratory function. Histology of second lung cancer was adenocarcinoma in 16 patients, squamous cell carcinoma in 9 patients and not assessed in 25 patients. The interval between index cancer operation and stereotactic body radiation therapy was 31 months (range: 4-171). The total stereotactic body radiation therapy doses were 48 Gy in 4 fractions or 60 Gy in 10 fractions.

RESULTS: With the median follow-up of 36 months, 3-year overall survival rates were 62% with the median survival time of 46 months. Cause-specific survival was 73% at 3 years. Overall survival for multiple primary lung cancer and pulmonary metastasis was quite similar: 62 and 61% at 3 years, respectively. Three-year overall survival was 77% for T1a and 43% for T1b or T2a. Grade 2 pulmonary toxicities occurred in five patients and one patient died of Grade 5 pneumonitis.

CONCLUSIONS: Even though the subjects were medically inoperable, the survival outcomes of stereotactic body radiation therapy were favorable. Furthermore, having acceptable toxicity, stereotactic body radiation therapy is feasible and could be an option for multiple primary lung cancer and pulmonary metastasis after surgical resection for the index cancer.