Reactive Oxygen Species Modulator 1 is Associated with Poor Survival in Patients with Non-Small Cell Lung Cancer After Stereotactic Fractionated Radiosurgery: A Retrospective Pilot Study

PURPOSE: It has been reported that the overexpression of reactive oxygen species modulator 1 (Romo1) is significantly associated with poor survival outcomes in patients with lung cancer who received surgical resection, conventional fractionated radiotherapy, and chemotherapy. In this study, we investigated whether Romo1 expression is associated with survival outcomes in patients with early-stage lung cancer who were treated with radiosurgery. METHODS: Romo1 protein expression was evaluated and scored in the tumor tissue specimens of 40 patients with non-small cell lung cancer by immunohistochemistry. An optimal cut-off for Romo1 expression was determined and used to allocate patients to low or high Romo1 expression groups. Survival outcomes were compared between the two groups. RESULTS: Romo1 expression was significantly associated with distant metastasis-free survival. The 1- and 2-year distant metastasis-free survival rates were 96.4% and 92.6% in the low Romo1 expression group and 87.5% and 46.7% in the high Romo1 expression group (P=0.041), respectively. The overall, local recurrence-free, regional recurrence-free, and disease progression-free survival rates were higher in the low Romo1 expression group than the high Romo1 expression group. However, the differences were not statistically significant. CONCLUSION: Romo1 overexpression is associated with poor distant metastasis-free survival in patients with non-small cell lung cancer treated with radiosurgery. Further, large-scale prospective studies are required to identify the clinical efficacy of Romo1 as a potential adverse prognostic factor in lung cancer.