Low rate of follow-up colonoscopy after positive results of colorectal cancer screening in a Chinese urban core district

Colorectal cancer (CRC) is one of the most common cancers in China. In 2003, a systematic CRC registry that enables the determination of CRC incidence and mortality and a CRC screening project were introduced in the Jing’an district of Shanghai by the municipal government. This study assessed the registry data to determine the status of CRC and CRC screening rates in the core district of an urban area of China. Data were retrieved from the Official registry information systems of Jing’an district Shanghai Cance. The incidence and mortality of CRC, as well as population-based CRC screening rates, were analysed. Individuals who screened positive for CRC based upon results of a high-risk factor questionnaire (HRFQ) and a faecal immunochemical test (FIT) were selected for follow-up colonoscopy (CSPY). From the registry data collected between 2003 and 2013, the standardized incidence rate was 26.44/105, with a significant gender difference. The CRC standardized mortality rate was 10.08/105. In 2013, 17,866 individuals (21.6%) enrolled for CRC screening among the 82,602 candidate residents. The positive screening rate was 16.28% (2909/17866). Among the 2909 positives, 508 (17.5%) underwent follow-up CSPY. In 41.3% of these individuals (210/508), abnormal lesions were detected. Of these, 8 (1.57%) lesions were diagnosed as CRC, and 142 (28.0%) were identified as precancerous lesions. During the assessment period, both the incidence and mortality of CRC in the Jing’an district were determined in the area of high CRC prevalence in Chin. Nevertheless, the rate of participation in CRC screening was low (21.6%), and the rate of participation in follow-up CSPY for individuals who screened positive was only 17.5%. Improved participation in CRC screening and follow-up CSPY is expected to lower the incidence and mortality of CRC significantly in the rural areas of China. (288)


Introduction
Colorectal cancer (CRC) is one of the most commonly diagnosed cancers in males and in females 84 worldwide. [1][2][3] CRC has a high prevalence, and it has become widely viewed as having a long 85 latency period, providing ample time for both early detection and prevention. Indeed, if diagnosed at 86 the earliest stage, CRC can be treated successfully, and most patients will survive for more than five 87 years.

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Research has shown that CRC screening reduces the incidence and mortality of CRC. A  In the urban areas of Shanghai, CRC was ranked higher in incidence (second) and mortality (fourth) 106 among all malignant tumours from the public data source released from the municipals. The Jing'an 107 district is small (0.12% of the total Shanghai area), but it is located in the core and most fruitful 108 centre of Shanghai in terms of economical and medical resources, with a higher life expectancy than 109 the entire Shanghai area in 2015. Owing to this situation, the residents of this district tend to live 110 there permanently. Therefore, this district appears appropriate for assessment of CRC incidence and 5 111 mortality, as well as the rate of participation in CRC screening, as a representative urban area in 112 China.

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To accurately assess CRC incidence and mortality and the rate of participation in CRC screening in 115 urban areas, the present study was conducted by retrieving the related informations of the residents 116 of the Jing'an district from the Registry Information Systems in Shanghai for analyses. The results 117 showed a high CRC incidence and mortality during the assessment period, together with a low 118 participation rate in CRC screening (21.6%). Notably, only 17.5% (508) of the 2,909 individuals 119 who screened positive for CRC were found to take follow-up colonoscopy (CSPY) in 2013.    Incidence and mortality rate and standardization 142 Data for the registered population was obtained from the Jing'an District Public Security Bureau to 143 calculate the crude incidence (mortality) rate. We used the 1966 world standard population 144 composition [17] to calculate the world population-adjusted incidence (mortality), which was 145 referred to as the standardized rate.  The FIT was performed 2 times per person at a one-week interval. Participants were informed of the 175 significance of the positive results and given a referral for CSPY to be carried out at a designated 176 hospital. These designated hospitals were asked to input CSPY information in a timely manner.

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Quality control 179 A random sample of 2% each day was checked, and the coincidence rate was not less than 90%.

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After the original questionnaire information was entered, the coincidence rate of the information 181 system and the questionnaire should be 100%. Categorical data were analysed using the Chi-square test, and a difference of P<0.05 was considered 185 statistically significant. Using SAS 9.1.3, we compared detection rates with Fisher's Exact Test 186 (two-sided) on both sides of the Exact P-value, recording the P-value of the Chi-square at the same 187 time. Chi-square was analysed by age group, using hierarchical analysis.  The age of onset of colon cancer ranged from 17 to 97 years, and the age of onset of rectal cancer 206 ranged from 13 to 99 years; the median values were 74 and 71 years, respectively. The incidence of 207 colon cancer and rectal cancer increased with age, and showed a rapid rise after about 50 years of 208 age; the peak was in the range of 75-80 years of age ( Fig.1 CRC incidence rate by age in males and 209 females (2003-2013) (/100 thousand)). Statistically significant gender differences in CRC incidence 210 were found (P=0.0431). The standardized incidence rate of colon cancer in males and females was 211 17.45/10 5 and 14.83/10 5 , respectively, and that of rectal cancer in males and females was 12.14/10 5 212 and 8.81/10 5 , respectively (  The crude and standardized CRC mortality rates were 33.10/10 5 and 10.08/10 5 (Table 3).  The age of death due to colon cancer ranged from 53 to 80 years of age, and the age of death due to 224 rectal cancer ranged from 80 to 100 years of age. The median age of death due to colon and rectal 225 cancers was 73 and 85 years, respectively. Colon cancer mortality increased at about 50 years of age, 226 with peak mortality at about 75 years of age, and then it decreased, exhibiting an "inverted V" shape.

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Rectal cancer mortality rose rapidly from about 75 years of age, increasing with age ( Fig. 3 /100 thousand)). There were also 229 statistically significant gender differences in CRC mortality (P=0.0201). The standardized mortality 230 rate of colon cancer in males and females was 9.53/10 5 and 6.77/10 5 , respectively, and that for rectal 10 231 cancer in males and females was 2.61/10 5 and 1.58/10 5 , respectively (Table 3 and (Table 4).  Table 5.   Table 7.   The diagnostic stages of CRC are shown in Table 9. were 15.1/10 5 for males and 11.6/10 5 for females. These rates of CRC incidence and mortality in 285 Shanghai were higher than those in the other core cities in China. Combined with the results of the 286 present study, it is evident that Shanghai is a city of high CRC incidence and mortality among 287 Chinese core cities, and the Jing'an district appears to be representative of an urban district of 288 Shanghai. Even though the rates of CRC incidence and mortality in the Jing'an district were 289 relatively high compared with other Chinese areas, they are still lower than those in the Western 290 countries. [1][2][3] In the US, the CRC incidence rate in 2010 was estimated at 40/10 5 , and the CRC