Abstract:

Background and purpose: The colorectal cancer screening program for community residents in Shanghai has been implemented for 12 years since 2013. This study aimed to analyze the impact of screening on the colorectal cancer incidence, stage and survival outcomes based on their screening participation status. Methods: This study used registry-based cohort study method. The registered residents in Shanghai from 2013 to 2017 who met the screening age range were divided into screening group and non-screening group. The data of colorectal cancer cases after being included in groups were obtained from the Population Based Cancer Registry. We calculated age-standardized cumulative incidence and age-group cumulative incidence, diagnosis stage and survival rate of colorectal cancer by gender, age and year of diagnosis. We used the Joinpoint regression method to calculate the annual change percentage for cumulative incidence trend analysis. The life table method and EdererⅡ method were used to calculate the 5-year observed survival rates and expected survival rates of colorectal cancer cases. Finally the 5-year relative survival rates were obtained. Results: The study included 1 687 689 participants aged 50-74 in screening group and 4 713 307 participants in non-screening group. During a 5-year follow-up period, there were 10 333 and 20 904 new cases of colorectal cancer diagnosed in the two groups, respectively. The age-standardized 5-year cumulative incidence in the screening group was 555.33/10⁵, with an average annual increase of 33.32% (P<0.05). The age-standardized 5-year cumulative incidence in the non-screening group was 529.85/10⁵, with an average annual increase of 48.13% (P<0.05). There was no statistically significant difference between the screening group and the non-screening group in the age-standardized 5-year cumulative incidence (X=0.25, P=0.804). The lower the age group, the greater the difference between the screening group and the non-screening group in the annual average change percentage of the age-standardized cumulative incidence. The stages 0-Ⅰ of newly diagnosed colorectal cancer cases in the screening group and non-screening group accounted for 14.70% and 7.46%, respectively, with a statistically significant difference in composition between the two groups (P<0.05). The 5-year relative survival rate of the screening group was 73.94%, while the non-screening group was 59.66%. The survival rate indicators of the former were significantly higher than those of the latter, and the difference was statistically significant. The survival rate of the former was significantly higher than that of the latter (73.94% vs 59.66%), and the difference was statistically significant (P<0.05). The survival rate of females in both groups of cases was higher than that of males, and the survival rate decreased with increasing age-groups at diagnosis. Conclusion: With the implementation of the colorectal cancer screening program, the growth trend of the incidence rate of colorectal cancer among the screening participants has been curbed, and the early stages of colorectal cancer cases diagnosed and the 5-year survival rate were significantly improved. In order to reduce the incidence rate of colorectal cancer in the whole population, it is necessary to vigorously promote the screening coverage of the appropriate population, especially to increase the proportion of lower age groups participating in screening. We should also pay attention to the screening quality of the elderly groups and improve the compliance of colonoscopy in high-risk participants. At the same time, we should further optimize the refined management of screening for different genders, ages, and risk groups.

Key words: Colorectal cancer, Screening, Cumulative incidence, Stage, Survival rate