Conditional relative survival in non-metastatic esophagogastric cancer between 2006 and 2020: a population-based study.

Conditional relative survival (CRS) is useful for communicating prognosis to patients as it provides an estimate of the life expectancy after having survived a certain time after treatment. This study estimates the three year relative survival conditional on having survived a certain period for patients with esophageal or gastric cancer. Patients with non-metastatic esophageal or gastric cancer diagnosed between 2006-2020 treated with curative intent (resection with or without (neo)adjuvant therapy, or chemoradiotherapy) were selected from the Netherlands Cancer Registry. CRS was calculated since resection or last day of chemoradiotherapy. The probability of surviving an additional three years (i.e. three year CRS), if the patients survived 1,3 and 5 years after diagnosis was 62%, 79%, 87% and 69%, 84%, 90% for esophageal and gastric cancer, respectively. The three year CRS after having survived 3 years for patients with esophageal cancer who underwent a resection (n=12,204) was 91%, 88%, 77% and 60% for pathological stage 0, I, II and III, and for patients with esophageal cancer who received chemoradiotherapy (n=4,158) was 51% and 66% for clinical stage II and III, respectively. The three year CRS after having survived 3 years for patients with gastric cancer who underwent a resection (n=6,531) was 99%, 90%, 73% and 59% for pathological stage 0, I, II and III, respectively. Despite poor prognosis of patients with esophageal or gastric cancer, life expectancy increases substantially after patients have survived several years after treatment. This study provides valuable information for communication of prognosis to patients during follow-up after treatment.