Salvage Esophagectomy Definition Influences Comparative Outcomes in Esophageal Squamous Cell Cancers

In retrospective studies the definition of salvage esophagectomy has been inconsistent and is a source of bias. We sought to describe how variability in the definition of salvage affects comparative outcomes of trimodality therapy (TMT) and bimodality therapy (BMT).

Patients with locally advanced esophageal squamous cell carcinoma who completed chemoradiation therapy (CRT) from 2002 to 2017 were identified. TMT included patients who had a planned esophagectomy after CRT. BMT included patients treated with CRT only plus salvage esophagectomy, variably defined as an esophagectomy occurring (A) 3 months after CRT; (B) 3 months after CRT, excluding delayed recovery; (C) 3 months after CRT, excluding delayed workup; or (D) 6 months after CRT. Long-term survival outcomes between the TMT and BMT groups were compared for each definition of salvage esophagectomy. Time to surgery was included a priori in a multivariable model for overall survival.

Of 143 patients, 90 (63%) underwent esophagectomy and 53 (37%) received CRT only. Although the total patients remained the same, the composition of the TMT and BMT groups varied by salvage definitions A through D. Various definitions resulted in different 5-year survival rates for TMT vs BMT groups: (A) 56% vs 39%, (B) 61% vs 34%, (C) 50% vs 42%, and (D) 51% vs 39%. In a Cox multivariable analysis age and proximal/middle esophageal tumors were associated with worse postoperative survival, but time to surgery was not.

Slight variations in the definition of salvage esophagectomy can influence the interpretation of TMT and BMT outcomes. Future studies should consistently define treatment groups.