Effects of omeprazole in improving concurrent chemoradiotherapy efficacy in rectal cancer

AIM: To explore the effects of omeprazole on chemoradiotherapy efficacy and tumor recurrence in rectal cancer. METHODS: The medical data of 125 rectal cancer patients who received the same neoadjuvant chemoradiotherapy (CRT) followed by surgery were retrospectively collected. Patients who received omeprazole (OME) orally at a dose of 20 mg at least once daily for six days and/or intravenously at 40 mg a day were recognized as eligible OME users (EOU). Otherwise, patients were regarded as non-eligible OME users (non-EOU). Moreover, a preferred OME dose cut-off of 200 mg on tumor recurrence was obtained by receiver operating characteristic (ROC) curves. Patients were divided into two groups: the effective OME group (EOG, OME ≥ 200 mg) and the non-effective OME group (non-EOG, OME < 200 mg). RESULTS: The good response rate of CRT efficacy (50.8%) in EOU was significantly increased compared with non-EOU (30.6%) (P = 0.02). The recurrence rate in the EOG was 10.3%, which was significantly lower compared with 31.3% in non-EOG (P = 0.025). The good response rate of CRT efficacy in EOG was 55.2%, which was obviously higher compared with 36.5% in non-EOG, with a significant difference (P = 0.072). Multivariate Cox analysis demonstrated that OME (non-EOG and EOG) was an independent and significant impact factor for DFS (P = 0.048, HR = 0.30, 95%CI: 0.09-0.99). CONCLUSION: When applied as an adjuvant drug in cancer treatment for relieving common side effects of chemotherapy, omeprazole has a synergetic effect in improving CRT efficacy and decreasing rectal cancer recurrence.