Tumour regression grade is an important prognostic indicator for patients undergoing neoadjuvant chemoradiotherapy. However, there is significant controversy regarding the prognostic implications when there is discordance between tumour regression grade in the primary tumour and lymph nodes. This study aims to clarify the impact of tumour regression grade discordance on prognosis for oesophageal cancer and identify potential causes for such discrepancies.

A total of 112 patients with oesophageal squamous cell carcinoma who received neoadjuvant chemoradiotherapy followed by surgical treatment were included. Cox univariate analysis was performed to evaluate the relationship between primary tumour regression grade, lymph node regression grade, and both recurrence-free survival and overall survival. Logistic univariate analysis was employed to identify factors contributing to primary tumour and lymph node regression grade discordance.

Primary tumour and lymph node regression grades, and nodal pathologic classification after preoperative therapy were significant factors influencing both recurrence-free and overall survival of patients with oesophageal cancer. Discordance between primary tumour and lymph node regression grades was observed in 38.4 % of cases. Factors such as radiotherapy modality (involved field or elective nodal irradiation), and the number of lymph nodes dissected were found to significantly affect the consistency between primary tumour and lymph node regression grades. When tumour regression grade discordance occurred, lymph node status had a more significant prognostic impact than the primary tumour.

Both primary tumour and lymph node regression grades are critical factors influencing recurrence-free survival. The number of lymph nodes dissected and the radiotherapy modality may contribute to discordance between the two indices. When discordance occurs, lymph node regression grade may hold more prognostic value than that of the primary tumour.