Oligometastatic recurrence as a prognostic factor after curative resection of esophageal squamous cell carcinoma

In recent years, the concept of oligometastasis, which represents limited metastatic disease, has gained much interest. This study focuses on the oligometastatic recurrence (OLR) of esophageal squamous cell carcinoma (ESCC) after esophagectomy. From among 514 patients who underwent curative resection for ESCC at our hospital between April 2005 and December 2019, 97 patients with recurrence were enrolled in this study. OLR was defined as fewer than five recurrences in a single organ. We analyzed the prognostic factors for patients with OLR after curative resection of ESCC, especially the relationship between the recurrence pattern and prognosis according to treatment, defined as metastasis-directed therapy (MDT) and chemotherapy with local therapy as combined local therapy (CLT). OLR was identified in 43 (44%) of the 97 patients with recurrence. The OLR group had a significantly better prognosis than the non-OLR group (P = 0.003). Multivariate analysis revealed that OLR was a prognostic factor after recurrence (P = 0.007) and that CLT after recurrence was the only prognostic factor in the OLR group (P = 0.024). The findings of this study suggest that OLR is a prognostic factor after resection of ESCC and that CLT is a promising treatment modality for patients with OLR after curative resection of ESCC.