This population-based study examines prognostic factors and survival trends among adults (15-99 years) diagnosed with small intestinal cancer in England and Wales during 1971-1990 and followed up to 1995. During this period, the 1- and 5-year age-standardised relative survival rates for small intestinal cancers combined were 42% and 23%, respectively. Duodenal tumours, adenocarcinomas, men, patients with advanced age and the most deprived patients had the poorest prognosis. For all small bowel tumours combined, the excess risk of death fell significantly by 6-9% every 4 years over the 20-year period (adjusted excess hazard ratio (EHR) 0.91 at 1 year after diagnosis, 0.94 at 5 years). For duodenal tumours, the EHR fell by about 14% (95% CI 5-22%) every 4 years between 1979 and 1990, and a similar trend for jejunal tumours was of borderline significance. Further population-based investigations linking survival data to individual data on diagnostic methods and types of treatment are needed. [ABSTRACT FROM AUTHOR]