Conditional survival in gastric cancer: a SEER database analysis

Background. Gastric cancer survival is typically reported in terms of survival from the time of diagnosis. Conditional survival is a more relevant measure of prognosis for patients who have already survived 1 or more years since diagnosis. Methods. Using the Surveillance, Epidemiology, and End Results (SEER 17) database from the National Cancer Institute, we analyzed data from 20018 gastric cancer patients diagnosed between 1988 and 1998. Using the life-table method, we computed 5-year relative conditional survival, grouped by summary stage, age, sex, and ethnicity, for patients who had already survived up to 5 years from diagnosis. Results. Relative conditional survival improves over time for all groups of gastric cancer patients who survive a period of time after diagnosis. The largest gains in conditional survival were seen in patients with advanced stage disease. In general, females showed better survival than males. When grouped by ethnicity, Asians continued to have improved survival compared to other ethnic categories, even at 5 years out from diagnosis. Conclusion. For gastric cancer patients who survive a period of time after diagnosis, the largest increases in conditional survival are seen for patients with advanced stage disease and for those less than 65 years old. Conditional survival can provide more relevant prognostic information than survival from the time of diagnosis for gastric cancer patients who survive a period of time after diagnosis.