Safety and efficacy of conversion therapy for metastatic esophageal cancer: exploratory analysis of JCOG1314

Recent advances in multimodal treatments indicate that conversion therapy (CT) is a viable option for metastatic esophageal cancer (EC). JCOG1314 was a randomized phase III trial to confirm the survival benefit of docetaxel plus cisplatin plus 5-fluorouracil (DCF) versus cisplatin plus 5-fluorouracil (CF) for metastatic EC. The purpose of this analysis was to evaluate the safety and survival of CT in patients enrolled in JCOG1314.

CT was defined as surgery or chemoradiotherapy (CRT) aimed at cure following initial treatment for tumors that were initially unresectable because of distant metastasis. Clinicopathological factors, surgical outcomes, toxicities during CRT, and survival were compared between the CT and non-CT groups.

Of 240 patients enrolled in JCOG1314, excluding patients with recurrent disease, 154 with initially unresectable EC because of distant metastasis were selected. Of these patients, 21 received CT, which included conversion surgery (n = 5) and conversion CRT (n = 16). There was no significant difference in the number of metastatic organs or chemotherapy regimen between the CT and non-CT groups. The most common M1 factor in the CT group was the thoracic lymph node. The 3-year overall survival (OS) for the CT and non-CT groups was 52.4 and 14.3%, respectively. Multivariable analysis revealed that CT patients showed significantly better OS compared with the non-CT group (HR 0.36, 95% CI 0.19-0.67, p < 0.01).

CT may be safely performed with a favorable prognosis in EC. A prospective study is warranted to determine whether CT improves survival in metastatic EC.