Recurrence Patterns of Oesophageal Squamous Cell Carcinoma Differ by Tumour Location and Pathologic Stage

OBJECTIVES: To investigate how recurrence patterns in oesophageal squamous cell carcinoma (ESCC) are influenced by primary tumour location, treatment modality, and pathologic stage, and distinguish true recurrence from frequent secondary primary malignancies. METHODS: A total of 953 ESCC patients (mean age, 62.6 ± 7.7 years, 883 [92.7%] male) who underwent curative-intent oesophagectomy between 2010 and 2020 were retrospectively analysed. Patients were categorized by tumour location (upper/mid vs lower), pathologic stage (0-I vs II-IV), and treatment modality (upfront surgery vs neoadjuvant chemoradiation). Recurrence patterns were classified as loco-regional, distant, or mixed. Secondary primary malignancies were also documented. Associations between recurrence patterns and post-recurrence survival (PRS) were assessed using multivariable Cox regression. RESULTS: Recurrence occurred in 23.4% (223/953) of patients, mostly within 2 years post-surgery (83.4%). Among early pathologic stage (0-I) patients treated with upfront surgery, upper/mid oesophageal cancers had a higher rate of loco-regional recurrence compared with lower oesophageal cancers (16.3% vs 6.7%; P = .003), particularly in the mediastinal (10.9% vs 4.8%) and supraclavicular lymph nodes (6.3% vs 1.4%). No location-related differences were observed in advanced pathologic stage (II-IV) or neoadjuvant chemoradiation groups. Distant recurrence predominated in the neoadjuvant chemotherapy group (19.6% vs 9.7%). The lung was the most frequent site of distant metastasis (7.6%-8.6%), presenting as solitary nodules (24/45). Secondary lung cancers occurred later than pulmonary recurrences (median 58.3 vs 6.9 months; P < .001). Mixed recurrence was associated with worse PRS (adjusted hazard ratio, 1.77; 95% confidence interval, 1.18-2.66; P = .006). CONCLUSIONS: ESCC recurrence patterns vary by tumour location, treatment modality, and pathologic stage. The lung is the most common site of distant recurrence and presents earlier than secondary lung cancer.