THE RISK OF ESOPHAGEAL CANCER IN PATIENTS WITH ACHALASIA - A POPULATION-BASED STUDY

Objective.-To determine more precise and accurate cancer risk estimate s for achalasia that could be used to plan surveillance. Design.-Cohor t. Setting.-Swedish population. Participants.--All patients with achal asia listed in the population-based Swedish Inpatient Register from 19 64 through 1989. Main Outcome Measures.-The observed number of cancers in the cohort was compared with expected numbers of cancers (standard ized incidence ratio [SIR]) for each 5-year age group and calendar yea r of observation, calculated using data from the Swedish Cancer Regist ry. 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 ac halasia diagnosis was extremely high (SIR, 126.3; 95% confidence inter val [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 40 6 endoscopic examinations in men and 2220 in women to detect one cance r. 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 w omen. It is not known whether surveillance will result in improved sur vival.