Evaluations Of CRC Incidence Patterns In China And The US And Modei Implementation For The Microsimulation Of Screening Strategies

Background:Colorectal cancer is one of the cancers with the highest morbidity and mortality in the world,while CRC incidence patters varied across different regions.CRC was not common in China,but a rapid rise was recently noticed:the US was among the countries with the highest incidence of CRC,but has experienced decreasing in CRC incidence for deeades,in which screening may have played a leading role.CRC screening programs are currently underway in many countries worldwide,but how to optimize screening strategies remains a challenge.This study includes 2 parts,in the first part we try to find out the differences of CRC incidence patterns between China and the US,and if possible,what may result in and what we could learn from the differences.In the second part,a new microsimulation model would be implemented for modeling the natural history of CRC and simulating the effects of screening interventions.Methods:In the first part,we extracted incidence data of 6 groups from CI5plus database by male and female,colon cancer and rectal cancer.Then we could compare the differences of CRC incidence patterns between China and the US by directly displaying data in tables and figures and by performing joinpoint regression analyses.In the second part,we collected information for CRC screening in Jiashan from 2007 to 2012.Participation rate,positive rate and early diagnosis rate were calculated and inputted to CMOST to evaluate the effects of the screening strategy in Jiashan.Results:Part 1:There was always a much higher incidence rate in the US than in China.However,a downward trend by 1%arnually from 1980s and an even increasing rapid pace by 3%to 4%annually from the beginning of 21st century(approximately 2003)in the US was narrowing the gap with the rising incidence rate in China e.g.by 1%annually in Shanghai and 3%annually in Jiashan,which happened mainly to colon cancer rather than rectal cancer.As to the time trends by age,it’s rather different between China and the US.In the US,age groups above 50y saw the decreasing incidence rates while the younger ones faced higher risks.It appeared almost the opposite in China,except the boundary was around 45y.CRC tends to be more common in older people in the US,while more younger cases occurred in China,but the age-specific pattern was approaching thanks to the opposite trends of CRC by age.Part 2:Totally 77349 completed CRC screening in 8 towns of Jiashan from 2007 to 2012,the participation rate was 84.2%for the first step,and 78.1%for the second step.19.68%was detected of adenomas or carcinomas,among which 500 cases were early diagnosis of CRC,indicated an early diagnosis rate of 92.9%.Predictions of CMOST showed that the screening strategy in Jiashan could reduce morbidity and mortality efficaciously(more than 30%),and detect CRC in earlier stage.Although far more colonoscopies were performed(5-fold)with screening,the total costs from screening and treatment didn’t vary with or without screening,proving the screening strategy cost-effective.Conclusion:A higher CRC incidence and a tendency of onset in older people were found in the US compared to China,but the gaps were being narrowed by the opposite trends.The changes of incidence patterns in the US could be attributed half or more to the uptake of screening,which should play a more important role in China to face the increasing challenge of CRC.New screening interventions testing in Jiashan were underway and and proved great potential,but there was still a long way to go.CRC screening strategies are recommended to be designed and optimized based on computer simulations rather than randomized CRC prevention trials as it’s more time-effective and cost-effective.Developing and implementing new microsimulation models according to Chinese populations should be an important way to optimize screening strategies in China.