Background: Population-based predictive factors for the effectiveness of second line palliative systemic therapy in gastro-oesophageal cancer are not available. This study investigates the... Show moreBackground: Population-based predictive factors for the effectiveness of second line palliative systemic therapy in gastro-oesophageal cancer are not available. This study investigates the predictive value of effectiveness of first-line treatment for second-line treatment outcomes in gastro-oesophageal cancer in a real-world setting. Methods: Patients with metastatic gastro-oesophageal cancer diagnosed in 2010-2017 who were treated with second-line therapy after disease progression on first-line therapy were identified from the Netherlands Cancer Registry. Patients were divided into four groups as per duration of time to treatment failure (TTF) of the first line (0-3, 3-6, 6-9 and >9 months), and the association with overall survival (OS) and second-line TTF was assessed using Kaplan-Meier curves and two-sided multivariable regression models. Results: Median OS since the start of the second line of patients (n Z 611) with first-line TTF of 0-3, 3-6, 6-9 and >9 months was 4.0, 4.1, 5.5 and 7.1 months, respectively (P < 0.001). Median second-line TTF of patients with first-line TTF of 0-3, 3-6, 6-9 and >9 months was 2.8, 2.4, 3.0 and 4.5 months, respectively (P < 0.001). Patients with first-line TTF of >9 months showed a longer OS than patients with first-line TTF of 0-3 months (adjusted hazard ratio (HR) 1.90; 95% confidence interval (CI) 1.46-2.47), 3-6 months (adjusted HR 1.88; 95% CI 1.47-2.39) and 6-9 months (adjusted HR 1.31; 95% CI 1.04-1.65). Results for second-line TTF were similar. Conclusions: This study shows a positive correlation between effectiveness of first-line therapy and outcomes of second-line therapy in gastro-oesophageal cancer. Physicians should take duration of the first line into account when considering second-line palliative systemic therapy. (c) 2021 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Show less