Probability model for estimating colorectal polyp progression rates

Cost-effectiveness Analysis of Colorectal Cancer Screening Strategies Using Active Learning and Monte Carlo Simulation

INTRODUCTION

Detection of colorectal cancer (CRC) in the early stages through available screening tests increases the patient's survival chances. Multimodal screening policies can benefit patients by providing more diverse screening options and balancing the risks and benefits of screening tests. We investigate the cost-effectiveness of a wide variety of multimodal CRC screening policies.

METHODS

We developed a Monte Carlo simulation framework to model CRC dynamics. We proposed an innovative calibration process using machine learning models to estimate age- and size-specific adenomatous polyps' progression and regression rates. The proposed approach significantly expedites the model parameter space search.

RESULTS

Two multimodal proposed policies (i.e., 1] colonoscopy at 50 y and fecal occult blood test annually between 60 and 75 y and 2] colonoscopy at 50 and 60 y and fecal immunochemical test annually between 70 and 75 y) are identified as efficient frontier policies. Both policies are cost-effective at a willingness to pay of $50,000. Sensitivity analyses were performed to assess the sensitivity of results to a change in screening test costs as well as adherence behavior. The sensitivity analysis results suggest that the proposed policies are mostly robust to the considered changes in screening test costs, as there is a significant overlap between the efficient frontier policies of the baseline and the sensitivity analysis cases. However, the efficient frontier policies were more sensitive to changes in adherence behavior.

CONCLUSION

Generally, combining stool-based tests with visual tests will benefit patients with higher life expectancy and a lower expected cost compared with unimodal screening policies. Colonoscopy at younger ages (when the colonoscopy complication risk is lower) and stool-based tests at older ages are shown to be more effective.

HIGHLIGHTS

We propose a detailed Markov model to capture the colorectal cancer (CRC) dynamics. The proposed Markov model presents the detailed dynamics of adenomas progression to CRC.We use more than 44,000 colonoscopy reports and available data in the literature to calibrate the proposed Markov model using an innovative approach that leverages machine learning models to expedite the calibration process.We investigate the cost-effectiveness of a wide variety of multimodal CRC screening policies and compare their performances with the current in-practice policies.

Shape-specific characterization of colorectal adenoma growth and transition to cancer with stochastic cell-based models

Colorectal adenoma are precursor lesions on the pathway to cancer. Their removal in screening colonoscopies has markedly reduced rates of cancer incidence and death. Generic models of adenoma growth and transition to cancer can guide the implementation of screening strategies. But adenoma shape has rarely featured as a relevant risk factor. Against this backdrop we aim to demonstrate that shape influences growth dynamics and cancer risk. Stochastic cell-based models are applied to a data set of 197,347 Bavarian outpatients who had colonoscopies from 2006-2009, 50,649 patients were reported with adenoma and 296 patients had cancer. For multi-stage clonal expansion (MSCE) models with up to three initiating stages parameters were estimated by fits to data sets of all shapes combined, and of sessile (70% of all adenoma), peduncular (17%) and flat (13%) adenoma separately for both sexes. Pertinent features of adenoma growth present themselves in contrast to previous assumptions. Stem cells with initial molecular changes residing in early adenoma predominantly multiply within two-dimensional structures such as crypts. For these cells mutation and division rates decrease with age. The absolute number of initiated cells in an adenoma of size 1 cm is small around 103, related to all bulk cells they constitute a share of about 10-5. The notion of very few proliferating stem cells with age-decreasing division rates is supported by cell marker experiments. The probability for adenoma transiting to cancer increases with squared linear size and shows a shape dependence. Compared to peduncular and flat adenoma, it is twice as high for sessile adenoma of the same size. We present a simple mathematical expression for the hazard ratio of interval cancers which provides a mechanistic understanding of this important quality indicator. We conclude that adenoma shape deserves closer consideration in screening strategies and as risk factor for transition to cancer.

Modeling colorectal cancers using multidimensional organoids

Organoids have revolutionized cancer research as highly adaptable models that enable an array of experimental techniques to interrogate tissue morphology and function. Because they preserve the genetic, phenotypic, and behavioral traits of their source tissue, organoids have gained traction as the most relevant models for drug discovery, tracking therapeutic response and for personalized medicine. As organoids are indisputably becoming a mainstay of cancer research, this review specifically addresses how colon-derived organoids can be perfected as multidimensional, scalable, reproducible models of healthy, pre-neoplastic and neoplastic conditions of the colon and for use in high-throughput "Phase-0" human clinical trials-in-a-dish.

Management Considerations for the Surgical Treatment of Colorectal Cancer During the Global Covid-19 Pandemic

OBJECTIVE

The COVID-19 pandemic requires to conscientiously weigh "timely surgical intervention" for colorectal cancer against efforts to conserve hospital resources and protect patients and health care providers.

SUMMARY BACKGROUND DATA

Professional societies provided ad-hoc guidance at the outset of the COVID-19 pandemic on deferral of surgical and perioperative interventions, but these lack specific parameters to determine the optimal timing of surgery.

METHODS

Using the GRADE system, published evidence was analyzed to generate weighted statements for stage, site, acuity of presentation, and hospital setting to specify when surgery should be pursued, the time and duration of oncologically acceptable delays, and when to utilize nonsurgical modalities to bridge the waiting period.

RESULTS

Colorectal cancer surgeries-prioritized as emergency, urgent with imminent emergency or oncologically urgent, or elective-were matched against the phases of the pandemic. Surgery in COVID-19-positive patients must be avoided. Emergent and imminent emergent cases should mostly proceed unless resources are exhausted. Standard practices allow for postponement of elective cases and deferral to nonsurgical modalities of stage II/III rectal and metastatic colorectal cancer. Oncologically urgent cases may be delayed for 6(-12) weeks without jeopardizing oncological outcomes. Outside established principles, administration of nonsurgical modalities is not justified and increases the vulnerability of patients.

CONCLUSIONS

The COVID-19 pandemic has stressed already limited health care resources and forced rationing, triage, and prioritization of care in general, specifically of surgical interventions. Established guidelines allow for modifications of optimal timing and type of surgery for colorectal cancer during an unrelated pandemic.

Cost-effectiveness and budget impact analyses of colorectal cancer screenings in a low- and middle-income country: example from Thailand

Objectives: Colorectal cancer (CRC) screening programs have been reported to be cost-effective in many high-income countries. However, there was no such study in low- and middle-income countries. This study aimed to evaluate cost-effectiveness and budget impact of CRC screening modalities for average-risk persons in Thailand.Methods: A decision tree coupled with a Markov model was used to estimate lifetime costs and health benefits of fecal immunochemical test (FIT) and colonoscopy using a societal perspective. The input parameters were obtained from a CRC screening project at a Thai tertiary care hospital, Thai health care costs and databases, and systematic literature review. Results were reported as incremental cost-effectiveness ratios (ICERs) in 2017 US Dollars (USD) per quality-adjusted life year (QALY) gained. Sensitivity analyses were performed to assess the influence of parameter uncertainty. Finally, budget impact analysis was conducted.Results: At the Thai ceiling threshold of societal willingness-to-pay of 4,706 USD, the screening colonoscopy every 10 years and annual FIT, starting at age 50, was cost-effective, as compared to no screening resulting in 15.09 and 15.00 QALYs with the ICERs of 600.20 and 509.84 USD/QALY gained, respectively. Colonoscopy every 10 years and annual FIT could prevent 17.9% and 5.7% of early stage cancer and 27.8% and 9.2% of late stage cancer per 100,000 screening over lifetime when compared to no screening, respectively. The colonoscopy screening was cost-effective with the ICER of 646.53 USD/QALY gained when compared to FIT. The probabilities of being cost-effective for the colonoscopy and FIT were 75% and 25%, respectively. Budget impact analysis showed the colonoscopy screening required an 8-times higher budget than FIT.Conclusions: Colonoscopy offers the best value for money of CRC screenings in Thailand. Annual FIT is potentially feasible since it requires less resources. Our findings can be used as part of evidence for informing policy decision making.Key points for decision makersThere was a lack of cost-effective study of colorectal cancer screening programs in low- and middle-income countries.This study evaluated lifetime health outcomes and costs, and the cost-effectiveness of colorectal screening options for average-risk persons in Thailand.Colonoscopy screening every 10 years is cost-effective with high probability of being cost-effective as compared with annual fecal immunochemical test.Screening by annual fecal immunochemical test is more feasible in terms of human resource and budgetary burden.Colorectal screening programs provides an opportunity for early diagnosis and treatments to prevent advance colorectal stages and avoid higher consequent costs.This study contributes a new evidence-based knowledge for Thailand and can be used to support policy decision making process.

Cost-effectiveness of high-sensitivity faecal immunochemical test and colonoscopy screening for colorectal cancer

BACKGROUND

Colorectal cancer screening can decrease morbidity and mortality. However, there are widespread differences in the implementation of programmes and choice of strategy. The primary objective of this study was to estimate lifelong costs and health outcomes of two of the currently most preferred methods of screening for colorectal cancer: colonoscopy and sensitive faecal immunochemical test (FIT).

METHODS

A cost-effectiveness analysis of colorectal cancer screening in a Swedish population was performed using a decision analysis model, based on the design of the Screening of Swedish Colons (SCREESCO) study, and data from the published literature and registries. Lifelong cost and effects of colonoscopy once, colonoscopy every 10 years, FIT twice, FIT biennially and no screening were estimated using simulations.

RESULTS

For 1000 individuals invited to screening, it was estimated that screening once with colonoscopy yielded 49 more quality-adjusted life-years (QALYs) and a cost saving of €64 800 compared with no screening. Similarly, screening twice with FIT gave 26 more QALYs and a cost saving of €17 600. When the colonoscopic screening was repeated every tenth year, 7 additional QALYs were gained at a cost of €189 400 compared with a single colonoscopy. The additional gain with biennial FIT screening was 25 QALYs at a cost of €154 300 compared with two FITs.

CONCLUSION

All screening strategies were cost-effective compared with no screening. Repeated and single screening strategies with colonoscopy were more cost-effective than FIT when lifelong effects and costs were considered. However, other factors such as patient acceptability of the test and availability of human resources also have to be taken into account.

How can screening colonoscopy be optimized?

Since the implementation of screening programmes, both the incidence and mortality of colorectal cancer have been decreasing. The choice of the preferred screening tool, however, is divergent and the adherence to screening programmes in most countries is still low. Cancer detection tests such as the guaiac faecal occult blood test (gFOBT) and the immunohistochemical FOBT (iFOBT) achieve higher acceptance than endoscopy. The sensitivity and specificity of iFOBT are higher than those of gFOBT, but gFOBT is cheaper and easier to perform. Endoscopic screening, which represents cancer prevention tests, has higher sensitivity for premalignant lesions than gFOBT and iFOBT and enables diagnosis and therapy in one single procedure. Since screening colonoscopy and sigmoidoscopy are invasive procedures with potentially severe adverse events, the highest possible quality must be provided. High-tech equipment, experience, training, quality control programmes, excellent bowel preparation and low adverse event rates are pivotal. Alternative screening tools such as CT colonography, barium enema CT and multitarget stool DNA tests have not been established as routine screening tools to date.

Identification of differential gene expressions in colorectal cancer and polyp by cDNA microarray

AIM: To screen the differential expressed genes in colorectal cancer and polyp tissue samples.

METHODS: Tissue specimens containing 16 cases of colorectal adenocarcinoma and colorectal polyp vs normal mucosae were collected and subjected to cDNA microarray and bioinformatical analyses. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to confirm some of the cDNA microarray data.

RESULTS: The experimental data showed that eight genes were differentially expressed, most of which were upregulated in adenomatous polyp lesions. Forty-six genes expressions were altered in colorectal cancers, of which 29 were upregulated and 17 downregulated, as compared to the normal mucosae. In addition, 18 genes were similarly altered in both adenomatous polyps and colorectal cancer. qRT-PCR analyses confirmed the cDNA microarray data for four of those 18 genes: MTA1, PDCD4, TSC1 and PDGFRA.

CONCLUSION: These differentially expressed genes likely represent biomarkers for early detection of colorectal cancer and may be potential therapeutic targets after confirmed by further studies.