Population-based Randomized Controlled Trial for Colorectal Cancer Screening in Nam Phong District, Khon Kaen Province in Thailand

• Main Authors: Pongdech Sarakarn, 沙龐得
• Other Authors: Hsiu-Hsi Chen
• Format: Others
• Language: en_US
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/x2wwc4

博士 === 國立臺灣大學 === 流行病學與預防醫學研究所 === 105 === Background Colorectal cancer (CRC) is an important health problem and a major cause of morbidity and mortality in worldwide. In Thailand, the trend of CRC incidence during the last two decades has been still slight increase in overall and noticeably increased in men. Although several randomized control trials (RCT) have demonstrated the effectiveness of population-based CRC screening using guaiac fecal occult blood test, there is no RCT to support the implementation of CRC screening using fecal immunochemical test (FIT) as a primary screening tool. It is of great interest to know the sample size and effectiveness while planning a population-based RCT for CRC screening with FIT for countries with intermediate or low incidence of CRC. Aims The objectives of this thesis are; (1) to describe changes in the incidence of CRC among four aged groups which consist of persons who aged under 45 years, aged 45 years and older, and persons who aged under 50 years, aged 50 years and older from 1989 to 2012, (2) to provide some details and the results to date of a colorectal cancer screening trial using FIT, (3) to simulate a hypothetical trial cohort by applying the five-state natural history of CRC model to project effectiveness, and to determine sample size based on primary and surrogate endpoints for the proposed population-based RCT for CRC screening in Kohn Kaen. Methods To describe the trends of CRC incidence rate, we retrieved the data from the Khon Kaen population-based cancer registry to analyze for describing the trend of CRC incidence rate between 1998 and 2012 among four aged groups (persons aged under 45 years, persons aged 45 years and older, persons aged under 50 years, and persons aged 50 years and older and the target population of the trial aged between 45 and 74. Joinpoint regression analysis was employed to detect changes in trends among each line segment and overall lines showing whether increasing or decreasing, using annual percent change (APC) and average annual percent change (AAPC), was statistically significant. The preliminary results of CRC screening of Khon Kaen in Thailand were reported. The projected effectiveness and sample size required for the proposed population-based RCT for colorectal cancer screening with FIT was assessed on the basis of natural progression of colorectal cancer from pre-clinical phase to clinical phase. Results Regarding the trends of CRC incidence rate, the crude and age-standardized incidence rates of CRC between 1989 and 2012 in Khon Kaen for those aged 45 years and older and those aged 50 years or older were found to be gradually increasing over time both when men and women were combined or considered separately. The rates for men were higher than for women through the period from 1989 to 2012, whereas CRC incidence tended to be higher in women than men over the same period. For preliminary results of CRC screening of Khon Kaen in Thailand, 92 people (8.7%) were positive for screening using FIT. This rate was higher than that reported from the previous study in Thailand, which indicated that the incidence of positive FIT cases in the screening programs may be increasing. Our results also showed that f-Hb concentrations vary with sex and age: the f-Hb concentrations were higher in older than in younger participants and higher in males than in females. Given 100% of attendance rate and 100% of colonoscopy compliance rate, biennial screening with FIT was anticipated to reduce 34% mortality of CRC and 52% advanced CRC. The sample sizes for primary and surrogate endpoints based on the projected incidence of 54 per 100,000 were 43,047 and 23,352, respectively. Conclusion The incidence of colorectal cancer in Khon Kaen, Thailand, has shown a gradual increase in both the elder and the young population. Future studies should consider subsite distributions of CRC. The f-Hb concentrations by sex and age from the preliminary results of the randomized controlled trial showed the same trend found in the literatures. Given the results of incidence and the preliminary results of this trial, we projected the effectiveness of screening with FIT and demonstrated the determination of sample size in planning a RCT with disease natural history underpinning by considering the distribution of disease from a specific area.