E473: Comparison of pathological complete response and survival outcomes in squamous cell carcinoma of oesophagus patients post CROSS protocol and curative surgery – a propensity matched analysis of real world data.

Introduction: To assess the relationship between pathological complete response post CROSS protocol in squamous cell carcinoma of oesophagus and survival outcomes in patients undergoing curative surgery in a real world scenario.

Methods: This is a retrospective analysis of a prospectively maintained electronic patient medical record. All patients who were diagnosed with squamous cell carcinoma of the oesophagus including gastro-oesophageal junction and treated with neoadjuvant chemoradiotherapy i.e. CROSS protocol followed by curative surgery between January 2019 and November 2022 were included in the study. The patients were matched for age, gender, clinical primary tumor and nodal staging in a 1:1 ratio and propensity analysis was done for the groups A (complete pathological response (pCR)) and B (no complete pathological response (npCR)). The continuous variables were analyzed using for mean, median and standard deviation, and comparisons were made using the Student’s t-test for mean and Mann–Whitney U test for median. Categorical data were described using proportions, and comparisons were performed using the chi-square test. The survival curves were obtained by Kaplan Meier analysis and Cox regression analysis was then performed for the significant factors

Results: During the period between January 2019 and November 2022, 56 patients of squamous cell carcinoma of the esophagus were operated post CROSS protocol. Out of the 56 patients, 29 had pCR (51.8%). 23 of these patients who had pCR (Group A) were then matched with 23 other patients with npCR (Group B). The median follow-up was for 40 months (CI 18.25 – 61.74). On survival analysis, group A had a median overall survival (OS) of 40 months (CI 22.45 – 57.54) vs. group B median overall survival of 18 months (CI 1.71-34.28) (p value = 0.025). The mean disease-free survival (DFS) was 35.12 months (CI 30.31 – 39.93) vs. 24.6 months (CI 13.75 -35.47) for groups A and B respectively (p value = 0.010). The survival outcomes did not vary with age, gender, stage of the disease. The pattern of recurrence was similar for local and regional amongst the two groups. The distant recurrences were more common in group B compared to group A (13% vs 0%, p value = 0.073).

Conclusions: pCR is the single most important driver of survival outcomes amongst patients undergoing CROSS protocol followed by curative surgery in squamous cell carcinoma of the oesophagus.