[Screening of colorectal cancer in Kunming urban residents from 2014 to 2017]

Objective: To explore the screening efficiency of colorectal cancer in urban residents of Kunming, China. Methods: Using the method of cluster sampling, from October 2014 to October 2017, residents of the three jurisdictions of Xishan, Guandu and Chenggong Districts of Kunming city were investigated. The inclusion criteria: (1) resident (for more than 3 years) population of Kunming city aged 40-74 years old; (2) voluntarily participating and receiving colonoscopy; (3) signing informed consent. Based on the Harvard Cancer Risk Index, the questionnaire was built on the consensus of more than 20 years of common cancer epidemiology in China. Through the consensus reached by the multidisciplinary expert panel discussion, a comprehensive evaluation system for cancer risk in China was designed. The high-risk group of colorectal cancer was determined by preliminary screening of the questionnaire, and a free colonoscopy was performed for the appointment to the gastrointestinal endoscopy department of the Yunnan Cancer Hospital. All polypoid lesions and ulcers found by colonoscopy must be biopsied to confirm the diagnosis. χ(2) test or Fisher exact probability method was used to compare the detection of colorectal cancer in 4 groups of 40-49 years old, 50-59 years old, 60-69 years old, and ≥70-years old. Detection of colonoscopy, compliance, pathological examination, pathological diagnosis, and morbidity of colorectal cancer were analyzed. Results: A total of 127 960 people from 40 to 74 years old of urban residents in Kunming city participated in the preliminary screening of the questionnaire, including 59 748 (46.7%) males and 68 212 females (53.3%) with mean age of (53.6±8.6) years old. The 40-49 years old group had the largest number of participants (48 044, 37.5%), followed by the groups of 50-59 years old (42 473, 33.2%), 60-69 years old (34 111, 26.7%), and ≥70 years old (3332, 2.6%). Till October 2017, a total of 14 971 people were screened as at high risk of colorectal cancer, with the high-risk detection rate of 11.7%, and the high-risk detection rate of women was significantly higher than that of men [13.4% (9 109/68 212) vs. 9.8% (5 862/59 748), χ(2)=386.947, P<0.001]. The highest high-risk detection rate was in the 50-59 years group in both gender [men: 11.1% (2202/19 831), women: 15.3% (3034/22 642)]. A total of 3449 people among the high-risk population received colonoscopy examination. The compliance rate of colonoscopy was 23.0% (3449/14 971), and the male compliance rate was 19.8% (1162/5862), which was significantly lower than that of females [25.1% (2287/9109), χ(2)=56.175, P<0.001]. The highest compliance was observed in the 50-59 years group [25.4% (1438/5668)], followed by 40-49 years and 60-69 year group [22.1%(1091/4931) and 22.0%(891/4048), respectively], and the compliance of ≥70 years old group was the lowest [9.0% (29/324)]. Colonoscopy examination revealed 606 cases with lesions, the detection rate of lesions was 17.6%, and the male detection rate was significantly higher than that of females [26.9% (313/1162) vs. 12.8% (293/2287), χ(2)=106.140, P<0.001]. The detection rate of lesions increased with age [40-49, 50-59, 60-69, ≥70: 10.9% (119/1091), 17.5% (252/1438), 25.0% (223/891) and 41.4% (12/29), respectively, χ(2)=79.010, P<0.001]. A total of 584 cases underwent endoscopic excision and pathological diagnosis, and 465 cases (13.5%) of precancerous lesions were detected. The prevalence of precancerous lesions in men was higher than that in women [21.3% (247/1162) vs. 9.5% (218/2287), χ(2)=90.801, P<0.001], the precancerous lesion detection rate increased with age [40-49, 50-59, 60-69, ≥70: 8.0% (87/1091), 14.3% (206/1438), 18.1% (161/891) and 37.9% (11/29); χ(2)=58.109, P<0.001]. A total of 4 patients with colorectal cancer were detected, including 3 males and 1 female. The detection rate of male colorectal cancer was 258.2/100 000, and the female was 43.7/100 000, whose difference was not statistically significant (χ(2)=1.488, P=0.223). There was no significant difference in the detection rate of colorectal cancer among 4 age groups [40-49, 50-59, 60-69, ≥70: 91.7/100 000 (1/1091), 69.5/100 000 (1/1438), 224.5/100 000 (2/891) and 0, respectively, P=0.696]. Conclusions: Screening for colorectal cancer is an important measure to control the onset and death of colorectal cancer. Through the questionnaire risk assessment plus colonoscopy, two-step screening method can improve the screening efficiency and greatly reduce the screening cost.