Interval Metastases After Neoadjuvant Chemoradiotherapy for Patients with Locally Advanced Esophageal Cancer: A Multicenter Observational Cohort Study

Background: 

Despite trimodality treatment, 10% to 20% of patients with esophageal cancer experience interval metastases after surgery. Restaging may identify patients who should not proceed to surgery, as well as a subgroup with limited metastases for whom long-term disease-control can be obtained. This study aimed to determine the proportion of patients with interval metastases after neoadjuvant chemoradiotherapy (nCRT) and to evaluate treatment and survival. 

Methods: 

Patients who had cT2-4aN0-3M0 esophageal cancer treated with nCRT were identified from a trial database. Metastases detected up to 14 weeks after nCRT on ¹⁸F-FDG-PET/CT or during surgery were categorized as oligometastases (≤3 lesions located in one single organ or one extra-regional lymph node station) or as non-oligometastases. The primary outcome was the proportion of patients with metastases after nCRT. The secondary outcomes were overall survival (OS) and the site and treatment of metastases. 

Results: 

Between 2013 and 2021, 973 patients received nCRT, and 10.3% had interval metastases. Of 100 patients, 30 (30%) had oligometastases, located mostly in non-regional lymph nodes (33.3%) or bones (26.7%). The median OS of this group was 13.8 months (95% confidence interval [CI] 9.2–27.1 months). Of 30 patients, 12 (40%) with oligometastases underwent potentially curative treatment, with a median OS of 22.8 months (95% CI 10.4–NA). The patients with non-oligometastases underwent mostly systemic therapy or BSC and had a median OS of 9 months (95% CI 7.4–10.9 months). 

Conclusions: 

Interval metastases were detected in about 10% of patients after nCRT, underscoring the importance of re-staging with ¹⁸F-FDG-PET/CT for those who proceed to surgery. A favorable survival might be accomplished for a subgroup of patients with oligometastases.