Oligometastatic disease in esophagogastric cancer

Patients with limited metastatic esophageal or gastric cancer (oligometastatic esophagogastric cancer) may benefit from local treatment of oligometastases combined with systemic therapy. This PhD thesis investigates the development of a multidisciplinary European consensus on the definition, diagnosis, and treatment of oligometastatic esophagogastric cancer (Part I) and evaluates the incidence and treatment strategies of this disease in clinical practice (Part II). Part I: The “OligoMetastatic Esophagogastric Cancer” (OMEC) project lays a detailed foundation for the approach to oligometastatic esophagogastric cancer. The OMEC project consists of 49 esophagogastric cancer expert centers across 16 different countries in Europe. The project, as described in the study protocol, includes first, a systematic review of the definitions of oligometastatic esophagogastric cancer in the literature and a meta-analysis of outcomes after local treatment of oligometastases; and second, multidisciplinary team considerations from cancer expert centers of real-life clinical cases of patients with oligometastatic esophagogastric cancer. To reach a broadly supported consensus on the best ways to define, diagnose, and treat oligometastatic esophagogastric cancer, the experts contributed to a Delphi consensus process as the third study. This has led, as a fourth step, to a series of recommendations that serve as guidelines for clinical practice. Part II: In studies on oligometastatic esophagogastric cancer in clinical practice, the prevalence and survival of patients with oligometastatic esophagogastric cancer were studied in multicenter cohort studies. These studies show that approximately one-quarter of patients with metastatic esophagogastric cancer have oligometastatic disease. The studies also suggest that the combination of local and systemic therapy can significantly improve overall survival compared to treatments that use only one of these approaches.