Changing Patterns of Distant Metastasis in Patients With Lower Rectal Cancer Undergoing Intraoperative Radiotherapy.

Abstract

Local radiotherapy for primary tumors may increase the incidence of distant metastasis. However, the patterns of target organs have not been clarified yet. 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. 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. After curative rectal cancer surgery with IORT, liver metastasis may be increased and accelerated.