Primary tumor burden score: A novel staging parameter for esophageal squamous cell carcinoma after neoadjuvant chemoradiotherapy

OBJECTIVES This study aims to develop a prognostic predictor that substitutes the current ypT-category based on the hypothesis that posttreatment tumour status can be represented by pretreatment tumour status and its changes during neoadjuvant chemoradiotherapy (nCRT). METHODS This retrospective cohort study included ESCC patients undergoing nCRT followed by surgery from January 1, 2010, to February 2, 2019. Eligible patients from the Department of Thoracic Surgery, Zhongshan Hospital of Fudan University were enrolled in the training cohort(n = 187), and from the Department of Cardiothoracic Surgery, Lu’an Affiliated Hospital of Anhui Medical University the validation cohort(n = 78). The Primary Tumour Burden Score (PTBS), calculated by multiplying the percentage of residual primary cancer cells and the pretreatment pathological T stage (prepT stage) after neoadjuvant therapy, was categorized into three groups using cutoff values of 0.20 and 2.80 (PTBS stage 1: ≤0.20; stage 2: 0.20–2.80; stage 3: >2.80). RESULTS Of the 187 patients included in the training cohort (158 man [84.5%]; median age at surgery, 62 [IQR, 56–67] years). The PTBS staging model outperformed the traditional parameters in terms of discriminatory power and goodness of fit (5-year AUC: PTBS vs ypT, prepT, cT, TRG, 0.720 vs 0.665, 0.623, 0.500, 0.664; AIC: PTBS vs ypT, prepT, cT, TRG, 736.03 vs 756.70, 762.72, 770.15, 756.34). Multivariable analysis indicated that PTBS independently predicted OS. Similar findings were observed in the validation cohort. CONCLUSIONS The PTBS stage showed superior prognostic discriminatory ability compared with traditional primary lesion stage parameters, suggesting its potential to serve as a valuable supplement to the current ypT-category.