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In their correspondence, Chien et al. shared data on the incidence of adenocarcinoma of the esophagus from Taiwan and presented comparisons with other data from the Far East. It appears that the rates are not rising in Hong Kong or Taiwan, in contrast to some increases suggested in Japan. Given the historically low prevalence in the Far East of risk factors such as obesity, gastroesophageal reflux disease, Barrett's esophagus, and cigarette smoking compared with Western countries, it may not be surprising that esophageal adenocarcinoma rates have been quite low and generally not rising in the Far East.
We noted with interest that Chien et al. showed in their table 1 that rates did rise in Japan, on the basis of rates that were back-calculated by use of the estimated annual percent changes presented by Shibata et al. (1). Although the incidence rates in Japan were quite low, the estimated annual percent changes during the time period 1993–2001 of 4.73 (95% confidence interval [CI] = 0.74 to 8.88) among men and 6.03 (95% CI = 2.37 to 9.82) among women were statistically significantly different from zero (null hypothesis of no change in rates over time) as shown in table 2 of Shibata et al. the authors interpreted the increase as not “dramatic.” These rates of change are in fact remarkably similar to the estimated annual percent changes among the US white population of 6.52 (95% CI = 5.83 to 7.22) among men and 5.95 (95% CI = 5.11 to 6.81) among women during the period 1973–2005 in the Surveillance, Epidemiology, and End Results nine registries (2,3). Not included in the correspondence by Chien et al. was a publication from Singapore by Fernandes et al. (4) that suggested rising incidence rates of esophageal adenocarcinoma among both men and women during the time period 1968–2002, although the trends did not reach statistical significance. We note, however, that the number of patients classified as having “other type” declined substantially in Singapore over time and may have contributed to the apparent increases in adenocarcinoma. The number of patients classified as having “other and unspecified type” did not decline in Japan and were not presented by Chien for Taiwan; changes in histological type specificity need to be considered when describing type-specific temporal trends.
Intramural Research Program of the National Institutes of Health, National Cancer Institute, Division of Cancer Epidemiology and Genetics to SSD and W-HC.