Non-preventable cases of breast, prostate, lung, and colorectal cancer in 2050 in an elimination scenario of modifiable risk factors.

Most Western countries have increasing number of new cancer cases per year. Cancer incidence is primarily influenced by basically avoidable risk factors and an aging population. Through hypothetical elimination scenarios of multiple major risk factors for cancer, we estimated the number of new cancer cases that are non-preventable in 2050. We compare numbers of new postmenopausal breast, prostate, lung, and colorectal cancer cases in 2021 to projected numbers of new cases in 2050 under prevention scenarios regarding smoking, overweight and obesity, and alcohol consumption: no intervention, 50%, and 100% instant reduction. Cancer incidence data were derived from NORDCAN, and risk factor prevalence data from the Danish National Health Survey. Cancer projections were calculated with the Prevent program. Hypothetical 100% instant elimination of major risk factors for cancer in Denmark in 2022 will result in unchanged numbers of new breast and colorectal cancers in 2050. The number of new prostate cancers will increase by 25% compared to 2021. Unchanged risk factor levels will result in noticeable increase in cancer burden. Increase in life expectancy and age will entail an increase in cancer incidence, despite maximum effect of preventive actions in the population. Our results are important when planning future health care.

Screening for Colorectal Cancer.

Colorectal cancer (CRC) is the second leading cause of cancer death. Screening has been proven to reduce both cancer incidence and cancer-related mortality. Various screening tests are available, each with their own advantages and disadvantages and varying levels of evidence to support their use. Clinicians should offer CRC screening to average-risk persons aged 50 to 75 years; starting screening at age 45 years remains controversial. Screening may be beneficial in select persons aged 76 to 85 years, based on their overall health and screening history. Offering a choice of screening tests or sequentially offering an alternate test for those who do not complete screening can significantly increase participation.

The implementation and mechanisms of advance notification for cancer screening: A scoping review.

OBJECTIVE: To describe and synthesise information on the content and delivery of advance notifications (information about cancer screening delivered prior to invitation) used to increase cancer screening participation and to understand the mechanisms that may underlie their effectiveness. METHODS: Searches related to advance notification and cancer screening were conducted in six electronic databases (APA PsycINFO, CINAHL, Cochrane Library, Embase, PubMed, Web of Science) and results were screened for eligibility. Study characteristics, features of the advance notifications (cancer type, format, delivery time, and content), and the effect of the notifications on cancer screening participation were extracted. Features were summarised and compared across effective versus ineffective notifications. RESULTS: Thirty-two articles were included in this review, reporting on 33 unique advance notifications. Of these, 79% were sent via postal mail, 79% were distributed prior to bowel cancer screening, and most were sent 2 weeks before the screening offer. Twenty-two full versions of the advance notifications were obtained for content analysis. Notifications included information about cancer risk, the benefits of screening, barriers to participation, social endorsement of cancer screening, and what to expect throughout the screening process. Of the 19 notifications whose effect was tested statistically, 68% were found to increase screening (by 0.7%-16%). Effectiveness did not differ according to the format, delivery time, or content within the notification, although some differences in cancer type were observed. CONCLUSION: Future research should explore the effectiveness of advance notification via alternative formats and for other screening contexts and disentangle the intervention- and person-level factors driving its effect on screening participation.

Study protocol for a mixed methods approach to optimize colorectal cancer screening in Malaysia: Integrating stakeholders insights and knowledge-to-action framework.

INTRODUCTION: Colorectal cancer is a growing global health concern and the number of reported cases has increased over the years. Early detection through screening is critical to improve outcomes for patients with colorectal cancer. In Malaysia, there is an urgent need to optimize the colorectal cancer screening program as uptake is limited by multiple challenges. This study aims to systematically identify and address gaps in screening service delivery to optimize the Malaysian colorectal cancer screening program. METHODS: This study uses a mixed methods design. It focuses primarily on qualitative data to understand processes and strategies and to identify specific areas that can be improved through stakeholder engagement in the screening program. Quantitative data play a dual role in supporting the selection of participants for the qualitative study based on program monitoring data and assessing inequalities in screening and program implementation in healthcare facilities in Malaysia. Meanwhile, literature review identifies existing strategies to improve colorectal cancer screening. Additionally, the knowledge-to-action framework is integrated to ensure that the research findings lead to practical improvements to the colorectal cancer screening program. DISCUSSION: Through this complex mix of qualitative and quantitative methods, this study will explore the complex interplay of population- and systems-level factors that influence screening rates. It involves identifying barriers to effective colorectal cancer screening in Malaysia, comparing current strategies with international best practices, and providing evidence-based recommendations to improve the local screening program.

Colorectal cancer initiation: Understanding early-stage disease for intervention.

How tumors arise or the cause of precancerous lesions is a fundamental question in cancer biology. It is generally accepted that tumors originate from normal cells that undergo uncontrolled proliferation owing to genetic alterations. At the onset of adenoma formation, cancer driver mutations confer clonal growth advantage, enabling mutant cells to outcompete and eliminate the surrounding healthy cells. Hence, the development of precancerous lesions is not only attributed to the expansion of pre-malignant clones, but also relies on the relative fitness of mutated cells compared to the neighboring cells. Colorectal cancer (CRC) is an excellent model to investigate cancer origin as it follows a stereotypical process from mutant cell hyperplasia to adenoma formation and progression. Here, we review the evolving understanding of colonic tumor development, focusing on how cell intrinsic and extrinsic factors impact cell competition and the "clone war" between cancer-initiating cells and normal stem cells. We also discuss the promises and limitations of targeting cell competitiveness in cancer prevention and early intervention. The field of tumor initiation is currently in its infancy, elucidating the adenoma origin is crucial for designing effective prevention strategies and early treatments before cancer becomes incurable.

Barriers to the use of tests for early detection of colorectal cancer in Chile.

This study aimed to assess the use of colorectal cancer (CRC) tests for prevention and early detection, alongside exploring the associated barriers to these tests. A stratified national survey was conducted in Chile, involving 1893 respondents (with a 2.3% error margin and 95% confidence interval). Logistic and multinomial regression analyses were employed to examine variations in test utilization likelihood and barrier. We found that the key determinants for undergoing CRC tests included age, health status, possession of private health insurance, and attainment of postgraduate education. Notably, 18% and 29% of respondents covered by public and private insurance, respectively, cited personal prevention as the primary motivation for test uptake. The principal obstacle identified was lack of knowledge, mentioned by 65% of respondents, while 29% and 19% of the publicly and privately insured respectively highlighted lack of access as a barrier. The results of this study provide valuable insights into factors influencing CRC screening, aiming to inform public health policies for expanding national coverage beyond diagnosis and treatment to encompass preventive measures.

Genetically Determined Circulating Lactase/Phlorizin Hydrolase Concentrations and Risk of Colorectal Cancer: A Two-Sample Mendelian Randomization Study.

Previous research has found that milk is associated with a decreased risk of colorectal cancer (CRC). However, it is unclear whether the milk digestion by the enzyme lactase-phlorizin hydrolase (LPH) plays a role in CRC susceptibility. Our study aims to investigate the direct causal relationship of CRC risk with LPH levels by applying a two-sample Mendelian Randomization (MR) strategy. Genetic instruments for LPH were derived from the Fenland Study, and CRC-associated summary statistics for these instruments were extracted from the FinnGen Study, PLCO Atlas Project, and Pan-UK Biobank. Primary MR analyses focused on a cis-variant (rs4988235) for LPH levels, with results integrated via meta-analysis. MR analyses using all variants were also undertaken. This analytical approach was further extended to assess CRC subtypes (colon and rectal). Meta-analysis across the three datasets illustrated an inverse association between genetically predicted LPH levels and CRC risk (OR: 0.92 [95% CI, 0.89-0.95]). Subtype analyses revealed associations of elevated LPH levels with reduced risks for both colon (OR: 0.92 [95% CI, 0.89-0.96]) and rectal cancer (OR: 0.92 [95% CI, 0.87, 0.98]). Consistency was observed across varied analytical methods and datasets. Further exploration is warranted to unveil the underlying mechanisms and validate LPH's potential role in CRC prevention.

Health behaviors, knowledge, screening, and attitudes toward colorectal cancer among Iraqi adults.

OBJECTIVE: This study aimed to evaluate the Iraqi population's health behaviors, knowledge, screening, attitudes toward colorectal cancer (CRC), and possible predictors that may affect their knowledge level. DESIGN: Cross-sectional study. SAMPLE: One thousand three hundred sixty-one Iraqi adults from Sulaymaniyah/Iraq. MEASUREMENTS: The odds ratio (OR) was used to find the association between knowledge of CRC and associated factors. RESULTS: Among participants, 6.1% had a colonoscopy, 4.0% had a sigmoidoscopy, and 60.8% heard CRC screening. Participants had low knowledge level of CRC risk factors (5.52 ± 1.39), and symptoms (3.73 ± 1.16) and had a medium knowledge of screening (4.35 ± 1.02). Respondents who retired (OR = 1.30; p = .00) and who had graduated from university (OR = 0.86; p = .01) had a high knowledge of CRC, while those who were aged 70 and above (OR = -1.08; p = .00) had a low knowledge of CRC. Furthermore, it was found that Iraqi adults who answered "no idea" to questions related to attitude and who answered incorrectly questions related to risk factors were likely to have low knowledge (p = .00). CONCLUSIONS: We found a lack of knowledge, screening, and misconceptions about CRC and screening among Iraqi adults. Thus, health training and screening programs should target Iraqi populations.

Exploring Gender Disparities in Factors Influencing Colorectal Cancer Screening Compliance in Singapore.

OBJECTIVE: The uptake of colorectal cancer (CRC) screening remains suboptimal in Singapore. Existing research highlights gender-related disparities in screening behaviors. This study aims to evaluate the gender differences in factors associated with CRC screening compliance in Singapore, with a specific focus on cancer screening beliefs and knowledge on CRC screening guidelines. METHODS: Data were collected from an online survey on cancer screening belief, knowledge, and practices in Singapore. Multivariate logistic regression analysis was conducted to identify independent factors associated with compliance in CRC screening. RESULTS: The study included 633 participants aged 50-69 years, eligible for CRC screening. Only 132 participants (20.9%) complied with CRC screening guidelines with no significant gender differences observed in compliance rates. Most participants held positive beliefs on routine screening (86.9%) and perceived screening benefits in improving treatment outcomes (89.6%) and reducing mortality rates (77.6%). However, both genders exhibited limited knowledge regarding CRC screening guidelines. Only 28.3% were aware that CRC screening should commence at age 50 years. While nearly half of participants knew FIT (44.7%) and colonoscopy (52.0%) as CRC screening modalities, only 27.5% and 15.2% recognized the recommended intervals for FIT and colonoscopy screening respectively. Multivariate analysis revealed a positive association between knowledge on CRC screening guidelines and CRC screening compliance for both genders. Gender-specific variations were observed in the factors associated with CRC screening compliance. Specifically, women with a family history of cancer, believing in routine cancer screening, and prior adherence to breast cancer screening and men within the older cohort (55-69 years) were more likely to comply with CRC screening. CONCLUSION: Low compliance with CRC screening was observed in Singapore. Targeted interventions should address gender-specific factors and highlight CRC screening guidelines as a crucial component of cancer education for entire screening eligible population in order to improve CRC screening compliance.

Knowledge and Perceptions of the Public VIS-À-VIS Colorectal Cancer Information in Newspapers in Malaysia.

OBJECTIVE: The study examines knowledge and perceptions of colorectal cancer vis-à-vis colorectal cancer information in newspapers in Malaysia. METHODS: A total of 152 respondents filled in a 76-item questionnaire based on the Health Belief Model. Articles on colorectal cancer in three English newspapers in Malaysia from 1 January to 30 June 2022 were analysed. RESULT: A majority of the Malaysian respondents had low experiential knowledge of colorectal cancer, high perceived severity, low perceived susceptibility, and low to moderate susceptibility based on self-reported lifestyle and health conditions. The diet factor puts a majority of respondents at risk but smoking, alcohol drinking, and large intestine problems are risk factors for less than 10% of the group. The respondents believed in the benefits of seeking treatment but they were only marginally positive as to whether quitting smoking and losing weight could reduce colorectal cancer risk. They reported strong response efficacy and self-efficacy but the top barriers were lack of knowledge and cost. The strongest cue to action for their health protective intentions was news about colorectal cancer in newspapers, magazines, television and youtube. There were positive moderate correlations among perceived severity, benefits, response efficacy, self-efficacy, cues to action, and intention. Little salience was given to colorectal cancer in the three English newspapers based on the number of articles (N=10). The high frequency of information on severity, susceptibility, and benefits of lifestyle changes and screening in the newspaper articles are reflected in questionnaire results on better knowledge. Lack of information and cost prevented respondents from seeking screening or treatment, despite attempts by the newspaper articles to address barriers. CONCLUSION: The study suggests a need to heighten cues to action in the mass media and social media by providing information on cost and practical details of colorectal cancer screening and benefits of diet-related risk factors.

Abnormal Colorectal Cancer Test Follow-Up: A Quality Improvement Initiative at a Federally Qualified Health Center.

INTRODUCTION/OBJECTIVES: Colonoscopy completion rates after an abnormal fecal immunochemical test (FIT) are suboptimal, resulting in missed opportunities for early detection and prevention of colorectal cancer. Patient navigation and structured follow-up may improve colonoscopy completion, but implementation of these strategies is not widespread. METHODS: We conducted a quality improvement study using a Plan-Do-Study-Act (PDSA) Model to increase colonoscopy completion after abnormal FIT in a large federally qualified health center serving a diverse and low-income population. Intervention components included patient navigation, and a checklist to promote completion of key steps required for abnormal FIT follow-up. Primary outcome was proportion of patients achieving colonoscopy completion within 6 months of abnormal FIT, assessed at baseline for 156 patients pre-intervention, and compared to 208 patients during the intervention period from April 2017 to December 2019. Drop offs at each step in the follow-up process were assessed. RESULTS: Colonoscopy completion improved from 21% among 156 patients with abnormal FIT pre-intervention, to 38% among 208 patients with abnormal FIT during the intervention (P < .001; absolute increase: 17%, 95% CI: 6.9%-25.2%). Among the 130 non-completers during the intervention period, lack of completion was attributable to absence of colonoscopy referral for 7.7%; inability to schedule a pre-colonoscopy specialist visit for 71.5%; failure to complete a pre-colonoscopy visit for 2.3%; the absence of colonoscopy scheduling for 9.2%; failure to show for a scheduled colonoscopy for 9.2%. CONCLUSIONS: Patient navigation and structured follow-up appear to improve colonoscopy completion after abnormal FIT. Additional strategies are needed to achieve optimal rates of completion.

Barriers and facilitators to implementing a multilevel, multicomponent intervention promoting colorectal cancer screening in health centers: a qualitative study of key informant perspectives.

BACKGROUND: Colorectal cancer (CRC) continues to be a major cause of death in the U.S. despite the availability of effective screening tools. U.S. Latinos have lower rates of CRC screening and higher rates of death due to colorectal disease compared to non-Hispanic whites. Federally Qualified Health Centers (FQHCs) serve medically underserved populations, including many Latino patients. Given the low CRC screening rates, identifying culturally sensitive and cost-effective methods of promoting screening is a priority for many FQHCs. METHODS: We interviewed FQHC leaders and providers using the Consolidated Framework for Implementation Research (CFIR) to identify barriers and facilitators to implementation of a multilevel, multicomponent (ML-MC) CRC screening intervention (i.e., promotor navigation and group-based education) in FQHCs. A rapid qualitative analysis approach was used to identify themes organized according to the following CFIR constructs: intervention characteristics, outer and inner settings, and characteristics of the individual. RESULTS: We completed interviews with 13 healthcare professionals in leadership positions at six FQHCs. The participating FQHCs perceived the ML-MC screening CRC program as feasible and expressed interest in implementing the program at their sites. Facilitators included financial incentives for increasing screening rates, the need for patient education programming, and involving promotores to support the work of clinical teams. Barriers included concerns about available resources to implement new programs, lack of federal reimbursement for health education, competing priorities of other health concerns, and the need for more resources for confirmatory screening and treatment following a positive screen. CONCLUSIONS: FQHCs provide essential primary care to millions of underserved patients in the U.S. and have the ability and motivation to provide screenings for colorectal cancer. Partnering with an academic institution to deliver a group-based, promotor-led CRC screening intervention for patients not up to date with screening could help increase screening rates. By identifying the specific barriers and facilitators to implementing CRC intervention, findings suggest that group-based, promotor-led interventions are a promising approach.

Association between adherence to a dietary approach to stop hypertension and the Mediterranean diets and risk of colorectal cancer: A matched case-control study.

BACKGROUND: Colorectal cancer (CRC) is one of the most common cancers and is currently the third leading cause of cancer-related deaths worldwide. This study aimed to evaluate whether the dietary approach to stop hypertension (DASH) and Mediterranean (MED) diets are associated with CRC in Iranian adults. METHODS: This hospital-based case-control study was conducted on 71 cases and 142 controls (40-75 years old) in three general hospitals in Tehran, Iran. The dietary intakes of individuals were collected through face-to-face interviews using a semi-quantitative food frequency questionnaire (FFQ) that included 125 food items. The DASH and MED diet scores were calculated according to food items based on guidelines. Two logistic regression models were applied to evaluate the association between DASH and MED score adherence. RESULTS: After adjusting for confounding factors, a negative association between DASH diet adherence and CRC risk was observed in the second and last tertile compared to the first tertile (T) (T2: odds ratio (OR) = 0.33; 95% confidence interval (CI): 0.14-0.77 - T3: OR = 0.09; 95% CI: 0.03-0.27). There was no significant association between the MED diet and the risk of CRC. CONCLUSIONS: In conclusion, the current study's findings presented that adherence to a DASH diet could reduce the odds of CRC.

Butyrate's (a short-chain fatty acid) microbial synthesis, absorption, and preventive roles against colorectal and lung cancer.

Butyrate, a short-chain fatty acid (SCFA) produced by bacterial fermentation of fiber in the colon, is a source of energy for colonocytes. Butyrate is essential for improving gastrointestinal (GI) health since it helps colonocyte function, reduces inflammation, preserves the gut barrier, and fosters a balanced microbiome. Human colonic butyrate producers are Gram-positive firmicutes, which are phylogenetically varied. The two most prevalent subgroups are associated with Eubacterium rectale/Roseburia spp. and Faecalibacterium prausnitzii. Now, the mechanism for the production of butyrate from microbes is a very vital topic to know. In the present study, we discuss the genes encoding the core of the butyrate synthesis pathway and also discuss the butyryl-CoA:acetate CoA-transferase, instead of butyrate kinase, which usually appears to be the enzyme that completes the process. Recently, butyrate-producing microbes have been genetically modified by researchers to increase butyrate synthesis from microbes. The activity of butyrate as a histone deacetylase inhibitor (HDACi) has led to several clinical trials to assess its effectiveness as a potential cancer treatment. Among various significant roles, butyrate is the main energy source for intestinal epithelial cells, which helps maintain colonic homeostasis. Moreover, people with non-small-cell lung cancer (NSCLC) have distinct gut microbiota from healthy adults and frequently have dysbiosis of the butyrate-producing bacteria in their guts. So, with an emphasis on colon and lung cancer, this review also discusses how the microbiome is crucial in preventing the progression of certain cancers through butyrate production. Further studies should be performed to investigate the underlying mechanisms of how these specific butyrate-producing bacteria can control both colon and lung cancer progression and prognosis.

Avocado and Guacamole Consumption and Colorectal Cancer Risk: The Multiethnic Cohort Study.

Dietary fiber and phytonutrients can protect against colorectal cancer, yet their consumption is low in the US. Avocados are a potential source of these beneficial nutrients. Therefore, this study aimed to examine the relationship between avocados/guacamole consumption and colorectal cancer risk in the Multiethnic Cohort Study. We assessed avocados/guacamole consumption by using a food frequency questionnaire. We classified participants into three consumer groups: <1 serving/month, 1-3 servings/month, and ≥1 serving/week with one serving defined as ½ avocado or ½ cup. Colorectal cancer cases were ascertained through the Surveillance, Epidemiology and End Results Program cancer registries. Cox proportional hazards models of colorectal cancer were used to calculate hazard ratios and 95% confidence intervals across avocados/guacamole intake groups in each sex overall and by anatomic subsite (i.e., right colon, left colon, and rectum) and race and ethnicity. Of 192,651 eligible participants, 62.8% reported consuming <1 serving/month avocados/guacamole, 26.7% reported 1-3 servings/month, and 10.5% reported ≥1 serving/week. When adjusted for relevant covariates, there was no significant association with incident colorectal cancer overall, for subsites, or within racial and ethnic subgroups (all p for trend ≥ 0.06). In this large prospective cohort study, we did not find that consumption of avocados/guacamole was associated with colorectal cancer risk.

Sex-specific associations of empirically derived dietary patterns with colorectal cancer risk in a Korean population: a case‒control study.

Dietary patterns may be a crucial modifiable factor in colorectal cancer (CRC) risk. This study aimed to examine the associations of dietary patterns derived from two methods with CRC risk in Korea. In a study of 1420 CRC patients and 2840 control participants, we obtained dietary patterns by principal component analysis (PCA) and reduced rank regression (RRR) using 33 predefined food groups. The associations between dietary patterns and CRC risk were assessed using unconditional logistic regression models to calculate odds ratios (ORs) and 95% confidence intervals (CIs). We identified two similar dietary patterns, derived from PCA 1 (prudent) and RRR (healthy), characterized by higher consumption of green/yellow vegetables, light-colored vegetables, fruits, eggs, and milk in both men and women. In women, higher prudent and healthy pattern scores were significantly associated with a lower risk of CRC (prudent, ORQ4 vs. Q1 = 0.59, 95% CI 0.40-0.86, P for trend = 0.005; healthy, ORQ4 vs. Q1 = 0.62, 95% CI 0.43-0.89, P for trend = 0.007). In men, a significant inverse association between dietary pattern and risk of rectal cancer was found only for the healthy dietary pattern (ORQ4 vs. Q1 = 0.66, 95% CI 0.45-0.97, P for trend = 0.036). Compared with the dietary pattern derived by PCA, the RRR dietary pattern had a slightly stronger association with a lower risk of distal colon cancer (ORQ4 vs. Q1 = 0.58, 95% CI 0.35-0.97, P for trend = 0.025) and rectal cancer (ORQ4 vs. Q1 = 0.29, 95% CI 0.15-0.57, P for trend < 0.001) in women. Our findings suggest cancer prevention strategies focusing on a diet rich in vegetables, fruits, eggs, and milk. Moreover, the use of both PCA and RRR methods may be advantageous to explore the associations between dietary patterns and risk of CRC.

Would initiating colorectal cancer screening from age of 45 be cost-effective in Germany? An individual-level simulation analysis.

Background: Colorectal cancer (CRC) screening has been shown to be effective and cost-saving. However, the trend of rising incidence of early-onset CRC challenges the current national screening program solely for people ≥50 years in Germany, where extending the screening to those 45-49 years might be justified. This study aims to evaluate the cost-effectiveness of CRC screening strategies starting at 45 years in Germany. Method: DECAS, an individual-level simulation model accounting for both adenoma and serrated pathways of CRC development and validated with German CRC epidemiology and screening effects, was used for the cost-effectiveness analysis. Four CRC screening strategies starting at age 45, including 10-yearly colonoscopy (COL), annual/biennial fecal immunochemical test (FIT), or the combination of the two, were compared with the current screening offer starting at age 50 years in Germany. Three adherence scenarios were considered: perfect adherence, current adherence, and high screening adherence. For each strategy, a cohort of 100,000 individuals with average CRC risk was simulated from age 20 until 90 or death. Outcomes included CRC cases averted, prevented death, quality-adjusted life-years gained (QALYG), and total incremental costs considering both CRC treatment and screening costs. A 3% discount rate was applied and costs were in 2023 Euro. Result: Initiating 10-yearly colonoscopy-only or combined FIT + COL strategies at age 45 resulted in incremental gains of 7-28 QALYs with incremental costs of €28,360-€71,759 per 1,000 individuals, compared to the current strategy. The ICER varied from €1,029 to €9,763 per QALYG, and the additional number needed for colonoscopy ranged from 129 to 885 per 1,000 individuals. Among the alternatives, a three times colonoscopy strategy starting at 45 years of age proves to be the most effective, while the FIT-only strategy was dominated by the currently implemented strategy. The findings remained consistent across probabilistic sensitivity analyses. Conclusion: The cost-effectiveness findings support initiating CRC screening at age 45 with either colonoscopy alone or combined with FIT, demonstrating substantial gains in quality-adjusted life-years with a modest increase in costs. Our findings emphasize the importance of implementing CRC screening 5 years earlier than the current practice to achieve more significant health and economic benefits.

Efficient organized colorectal cancer screening in Shenzhen: a microsimulation modelling study.

BACKGROUND: Colorectal cancer (CRC) is a global health issue with noticeably high incidence and mortality. Microsimulation models offer a time-efficient method to dynamically analyze multiple screening strategies. The study aimed to identify the efficient organized CRC screening strategies for Shenzhen City. METHODS: A microsimulation model named CMOST was employed to simulate CRC screening among 1 million people without migration in Shenzhen, with two CRC developing pathways and real-world participation rates. Initial screening included the National Colorectal Polyp Care score (NCPCS), fecal immunochemical test (FIT), and risk-stratification model (RS model), followed by diagnostic colonoscopy for positive results. Several start-ages (40, 45, 50 years), stop-ages (70, 75, 80 years), and screening intervals (annual, biennial, triennial) were assessed for each strategy. The efficiency of CRC screening was assessed by number of colonoscopies versus life-years gained (LYG). RESULTS: The screening strategies reduced CRC lifetime incidence by 14-27 cases (30.9-59.0%) and mortality by 7-12 deaths (41.5-71.3%), yielded 83-155 LYG, while requiring 920 to 5901 colonoscopies per 1000 individuals. Out of 81 screening, 23 strategies were estimated efficient. Most of the efficient screening strategies started at age 40 (17 out of 23 strategies) and stopped at age 70 (13 out of 23 strategies). Predominant screening intervals identified were annual for NCPCS, biennial for FIT, and triennial for RS models. The incremental colonoscopies to LYG ratios of efficient screening increased with shorter intervals within the same test category. Compared with no screening, when screening at the same start-to-stop age and interval, the additional colonoscopies per LYG increased progressively for FIT, NCPCS and RS model. CONCLUSION: This study identifies efficient CRC screening strategies for the average-risk population in Shenzhen. Most efficient screening strategies indeed start at age 40, but the optimal starting age depends on the chosen willingness-to-pay threshold. Within insufficient colonoscopy resources, efficient FIT and NCPCS screening strategies might be CRC initial screening strategies. We acknowledged the age-dependency bias of the results with NCPCS and RS.