Metastasis-directed local therapy and strategic de-escalation of systemic therapy for oligometastatic esophageal squamous cell carcinoma.

The introduction of immune checkpoint inhibitors (ICIs) has transformed the treatment of advanced esophageal squamous cell carcinoma (ESCC), yet the optimal duration of systemic therapy remains unsolved. Pivotal phase III trials capped ICI administration at 24 months, a design choice supported only indirectly by evidence from other tumor types suggesting a biological plateau in the antitumor immune response, since direct ESCC-specific evidence is lacking. In practice, however, 'oncological inertia,' the indefinite continuation of ICI therapy without a predefined stopping rule or objective marker of safety, contributes to cumulative toxicity and financial burden. This review proposes a 'strategic de-escalation' framework as an exit strategy. This framework uses metastasis-directed local consolidation therapy (LCT), surgical metastasectomy or ablative/precision radiotherapy to oligometastatic foci. This approach achieves definitive control of residual disease and thereby recasts subsequent ICI as a finite-duration adjuvant course. This course is analogous to postoperative nivolumab after chemoradiotherapy. It is an alternative to open-ended maintenance. Immediate, circulating tumor DNA (ctDNA)-driven discontinuation without an adjuvant course is a plausible but currently unproven alternative. Direct ESCC evidence for this exit strategy remains limited, and randomized trials in esophagogastric adenocarcinoma (REGATTA, RENAISSANCE) caution that aggressive local intervention can worsen outcomes without rigorous patient selection. The oligometastatic esophageal squamous cell carcinoma project uses a modified Delphi method to standardize the definition of oligometastatic ESCC and identify appropriate candidates. CtDNA may eventually guide the timing of treatment interruption and rechallenge. We discuss the rationale, current limitations, and prospective validation needs for this strategy in the multidisciplinary management of ESCC.