Novel methods of analyzing long-term trends in incidence and survival applied to gastroesophageal cancers.

Abstract

e14512 Background: The incidence of esophageal squamous cell (ESC) carcinoma has been decreasing, while incidence of esophageal adenocarcinoma (EA) keeps increasing. The specific time periods during which incidence trends changed have not been examined. Secular trends in survival and changes of those trends need to be investigated. Methods: Incidence and survival were analyzed using joinpoint regression models, which are designed to examine long-term longitudinal data for a change in trend. We identified 75,497 patients with esophageal cancer and adenocarcinoma of the gastric cardia (GCA) in the Surveillance, Epidemiology, and End Results database between 1973 and 2008. Incidence and one-year survival rates for ESC, EA, and GCA were compared by race, gender and stage. Results were expressed in terms of identifiable inflexion points (joinpoints) with before-and-after estimates of annual percent changes (APC) with 95% confidence intervals (CI). Results: Incidence of ESC has demonstrated a clear inflexion point in the mid 1980s with accelerated decrease across race and gender categories. While incidence of EA has been increasing, the increase slowed down in mid 90s in all groups except blacks. For GCA, there was a clear increase in incidence up until early 80s followed by a plateau although in men there was a significant post-87 decrease. One-year survival of ESC patients has been improving; for local/regional disease the trend became less pronounced in late 80s whereas for distant disease the improvement appears to continue without identifiable inflexion points. The patterns of one-year survival for EA and GCA were similar. Local/regional diseases demonstrated a significant improvement in survival without changes in trend while survival of distant diseases showed an inflexion point in the mid 90s followed by a marked improvement. Conclusions: Joinpoint regression analysis is a valuable tool in assessing long-term trends of incidence and survival. The survival of ESC, EA, and GCA demonstrated significant improvement over the last 35 years. The inflexion points reflected introduction of combined modality therapy for regional disease and availability of newer chemotherapy agents for distant disease.