Identification on surrogating overall survival with progression-free survival of first-line immunochemotherapy in advanced esophageal squamous cell carcinoma-an exploration of surrogate endpoint

Recurrence-free survival as a surrogate endpoint for overall survival after neoadjuvant chemotherapy and surgery for oesophageal squamous cell carcinoma

BACKGROUND

Overall survival is considered as one of the most important endpoints of treatment efficacy but often requires long follow-up. This study aimed to determine the validity of recurrence-free survival as a surrogate endpoint for overall survival in patients with surgically resectable advanced oesophageal squamous cell carcinoma (OSCC).

METHODS

Patients with OSCC who received neoadjuvant cisplatin and 5-fluorouracil, or docetaxel, cisplatin and 5-fluorouracil, at 58 Japanese oesophageal centres certified by the Japan Esophageal Society were reviewed retrospectively. The correlation between recurrence-free and overall survival was assessed using Kendall's τ.

RESULTS

The study included 3154 patients. The 5-year overall and recurrence-free survival rates were 56.6 and 47.7% respectively. The primary analysis revealed a strong correlation between recurrence-free and overall survival (Kendall's τ 0.797, 95% c.i. 0.782 to 0.812) at the individual level. Subgroup analysis showed a positive relationship between a more favourable pathological response to neoadjuvant chemotherapy and a higher τ value. In the meta-regression model, the adjusted R2 value at the institutional level was 100 (95% c.i. 40.2 to 100)%. The surrogate threshold effect was 0.703.

CONCLUSION

There was a strong correlation between recurrence-free and overall survival in patients with surgically resectable OSCC who underwent neoadjuvant chemotherapy, and this was more pronounced in patients with a better response to neoadjuvant chemotherapy.