Longitudinal trends of stomach cancer and esophageal cancer in Yangzhong County: a high-incidence rural area of China

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Abstract
This study aims to investigate the recent trends in incidence rates of stomach cancer and esophageal cancer in a high-incidence rural area of China. All new cancer occurrences registered between 1991 and 2003 in the Yangzhong Cancer Registry were reviewed. Yearly age-specific and age-adjusted incidence rates were calculated for males and for females. Longitudinal trends of cancer incidence were estimated by the estimated annual percentage change method. In total 12 691 incident cancer cases were registered, with 7159 males (56.41%) and 5532 females (43.59%). Adjusting to the world standard population, the incidence rate of all cancers decreased significantly across the period 1991–2003 from 357.02 to 283.21 per 105 person-years. For males this rate decreased from 447.22 to 346.72 per 105 person-years, and for females the incidence rate decreased from 284.36 to 225.73 per 105 person-years. The major cancers in Yangzhong County were stomach cancer and esophageal cancer, accounting for more than 70% of all cancer occurrences. During the past 13 years, the incidence rates of stomach cancer decreased greatly from 231.92 to 145.26 per 105 person-years in males and from 114.16 to 74.59 per 105 person-years in females. The estimated annual percentage changes of stomach cancer incidence were −2.96% [95% confidence interval (CI), −2.99% to −2.92%] in males and −2.86% (95% CI, −2.89% to −2.82%) in females. Incidence rates for esophageal cancer decreased slightly from 121.48 to 93.84 per 105 person-years in males with an estimated annual percentage change of −1.39% (95% CI, −1.42% to −1.36%), and from 99.74 to 73.73 per 105 person-years in females at an annual change of −2.18% (95% CI, −2.22% to −2.14%). Findings from this study showed that, although there is a decreasing trend of stomach cancer and esophageal cancer in this high-incidence area, the rates remain high. Future effort should be directed toward identifying factors behind the high rates and those contributing to the decreasing trend.