OBJECTIVETo understand the distribution of esophageal squamous cell cancer and precursor lesions in high-risk areas of China, and to provide evidence for determining the reference ranges of detection rates in high-risk areas.

METHODSEndoscopy with Lugol's iodine staining was performed on 15 709 local residents aged 40 to 69 years old in Linzhou of Henan province and Feicheng of Shandong province from 2005-2009. 35 cases without accurate pathology diagnosis and 11 cases with vital disease before screening were excluded. 15 663 subjects were enrolled in this study. Compliance was calculated by the percentage of the people who had endoscopic screening among the target population. Chi-square test and trend chi-square test were used to compare the distribution differences in age, gender and areas of esophageal squamous cell cancer and precancer. 95% CI of the detection rates was then employed to represent the reference ranges of esophageal squamous cell cancer and precursor lesions.

RESULTSThe compliance rate of screening endoscopy of this study was 49.36% (15 709/31 826) of all, and female's compliance (54.05%, 8 447/15 628) was much higher than that of male (44.83%, 7 262/16 198) (χ(2) = 88.14, P < 0.001). The detection rates of basal cell hyperplasia, low grade intraepithelial neoplasia, high grade intraepithelial neoplasia and esophageal squamous cell cancer of males were 4.17% (302/7 246), 17.22% (1 248/7 246), 1.67% (121/7 246), 0.83% (60/7 246), and were higher than that of females (3.45% (290/8 417), 14.82% (1 247/8 417), 1.41% (119/8 417), 0.48% (40/8 417), respectively). Except for high-grade intraepithelial neoplasia, the detection rates of male were higher than that of female (P values were 0.018, < 0.001, 0.960, 0.006). The detection rates of all grades of precursor lesions increased with age rising (all P values < 0.001), among which the detection rates of the mentioned four lesions for 40-44 years old were 2.69% (94/3 500), 8.11% (284/3 500), 0.40% (14/3 500), 0.14% (5/3 500), and that of 65-69 years old were 5.46% (46/843), 23.25% (196/843), 3.68% (31/843), 2.14% (18/843). The proportion of esophageal precursor lesion of Linzhou were higher than that of Feicheng observably except for esophageal squamous cell cancer (P values were < 0.001, < 0.001, < 0.001, 0.437). The detection rates of the four lesions of Linzhou and Feicheng were 4.90% (504/10 287), 17.37% (1 787/10 287), 1.79% (184/1 0287), 0.60% (62/10 287) and 1.64% (88/5 376), 13.17% (708/5 376), 1.04% (56/5 376), 0.71% (38/5 376). The 95% CI of detection rates of various lesions were, 3.78% (3.48%-4.08%) for basal cell hyperplasia, 15.93% (15.37%-16.50%) for low-grade intraepithelial neoplasia, 12.31% (11.79%-12.82%) for mild dysplasia and 3.62% (3.33%-3.91%) for moderate hyperplasia, 1.53% (1.34%-1.72%) for high-grade intraepithelial neoplasia and 0.64% (0.51%-0.76%) for esophageal squamous cell cancer, respectively.

CONCLUSIONUp to 21.88% residents that were asymptomatic were suffered from esophageal squamous cancer or precursor lesions in high-risk areas in China. The distribution of esophageal squamous cell cancer and precursor lesions was closely related to the gender and the age, which suggested that males were supposed to be paid more attention to.