Objective: To determine more precise and accurate cancer risk estimates for achalasia that could be used to plan surveillance.
Design: Cohort.
Setting: Swedish population.
Participants: All patients with achalasia listed in the population-based Swedish Inpatient Register from 1964 through 1989.
Main outcome measures: The observed number of cancers in the cohort was compared with expected numbers of cancers (standardized incidence ratio [SIR]) for each 5-year age group and calendar year of observation, calculated using data from the Swedish Cancer Registry.
Results: A total of 1062 patients with achalasia accumulated 9864 years of follow-up. The mean age at entry was 57.2 years, and the mean age at cancer diagnosis was 71.0 years. Esophageal cancer occurred in 24 patients. The risk of esophageal cancer in the first year after achalasia diagnosis was extremely high (SIR, 126.3; 95% confidence interval [CI], 63.0 to 226.1) as a consequence of prevalent cancers leading to distal esophageal obstruction simulating achalasia. During years 1 to 24, the risk was increased more than 16-fold (SIR, 16.6; 95% CI, 8.8 to 28.3). Annual surveillance after the first year would require 406 endoscopic examinations in men and 2220 in women to detect one cancer.
Conclusions: Patients with achalasia are at markedly increased risk of developing esophageal cancer. A substantial number of surveillance examinations might be required to screen for cancers, especially in women. It is not known whether surveillance will result in improved survival.