Purpose: Reactive oxygen species modulator 1 (ROMO1) is a novel protein regulating intracellular reactive oxygen species production. Although increased ROMO1 expression has been associated with poor clinical outcomes in several human malignancies, the clinical implication of this protein in a radiotherapy setting has never been explored. The aim of this study was to investigate whether ROMO1 expression is associated with survival in lung cancer patients who received radiotherapy.

Methods: ROMO1 protein expression was evaluated immunohistochemically using histologic score (H-score) in 49 tumor tissues from stage III non-small cell lung cancer (NSCLC) patients treated with definitive radiotherapy. We performed survival analyses according to various clinicopathological parameters including ROMO1 expression.

Results: ROMO1 expression was not associated with any clinicopathological parameter of age, sex, smoking status, stage, or histological subtype. Multivariate analyses showed that high ROMO1 expression was independently associated with worse progression-free survival (hazard ratio [HR] = 1.87, 95% confidence interval [CI]: 1.02-4.23) and with worse overall survival (HR = 2.79, 95% CI:1.13-6.87). In addition, high ROMO1 expression was independently associated with shorter time to loco-regional recurrence (HR=2.71, 95% CI:1.04-6.28) but was not associated with time to distant metastasis.

Conclusion: ROMO1 overexpression was associated with early loco-regional recurrence and poor survival outcomes in stage III NSCLC treated with definitive radiotherapy. Our exploratory results provide a basis for further large-scale studies to validate whether ROMO1 could be a prognostic marker in this setting.