Changing Patterns Of Distant Metastasis In Patients With Lower Rectal Cancer Undergoing Intraoperative Radiotherapy

Background/Aim: Local radiotherapy for primary tumors may increase the incidence of distant metastasis. However, the patterns of target organs have not been clarified yet. Patients and Methods: In our randomized controlled trial examining the oncological efficacy of intraoperative radiotherapy (IORT) for advanced lower rectal cancer, the details of the metastatic organs were evaluated. Results: In the IORT group (38 patients), 2 patients had metastasis in the liver and lung simultaneously, 9 in the liver, and 4 in the lung. In the control group (38 patients), 3 had metastasis in the lung, and 2 in the liver. The IORT group tended to have liver metastases more frequently (p=0.058). Among patients with liver metastases, distant metastasis-free intervals were significantly shorter in the IORT group, however, no significant difference was observed among patients with lung metastases. Conclusion: After curative rectal cancer surgery with IORT, liver metastasis may be increased and accelerated.