Impact of prior cancer history on survival of patients with gastric cancer.

Background: Patients with prior cancer history are commonly excluded from clinical trial. However, the impact of prior cancer on survival of patients with gastric cancer remains largely unknown. The aim of this study was to evaluate the prevalence of prior cancer and assess its impact on survival of patients diagnosed with gastric cancer.
Methods: Patients with gastric cancer as the primary or second primary malignancies diagnosed from 2004 to 2010 were extracted from the Surveillance, Epidemiology, and End Results (SEER) database. Propensity score matching (PSM) was conducted to balance baseline characteristics. Kaplan-Meier method, multivariate Cox proportional hazard model, and multivariate competing risk model were performed for survival analysis.
Results: A total of 28,795 eligible patients with gastric cancer were included, of whom 2695 (9.35%) had a history of prior cancer. Prostate (35%), breast (12%), colon (8%), and urinary bladder (7%) malignancies were the most common prior cancer types. Patients with prior cancer history had slightly inferior overall survival (AHR = 1.06; 95% CI [1.00-1.12]; P = 0.043) but superior gastric cancer-specific survival (AHR = 0.82; 95% CI [0.76-0.88]; P < 0.001) compared with those without prior cancer. The subgroup analysis determined that a prior cancer history did not adversely affect gastric patients' clinical outcomes, except in those with prior cancer diagnosed within one year, at distant stage, or originating from lung and bronchus.
Conclusion: A substantial proportion of gastric cancer patients with a history of prior cancer had non-inferior clinical outcome to those without prior cancer. These patients should be considered in clinical trials.
Competing Interests: Declaration of competing interest The authors declare that there are no conflicts of interest associated with the publication of this manuscript.
(Copyright © 2021. Published by Elsevier Ltd.)