Benefits, Harms, and Cost-Effectiveness of Potential Age Extensions to the National Bowel Cancer Screening Program in Australia

Risk factors, histopathological landscape, biomarkers, treatment patterns and survival of early-onset colorectal cancer: A narrative review

Early-onset colorectal cancer (EOCRC) incidence has increased in most Western countries over the last decade, with Australia at the forefront. Recent literature has thus focused on characterizing EOCRC from later-onset colorectal cancer (LOCRC). Earlier exposure to modifiable risk factors resulting in gut dysbiosis has been linked with EOCRC development. EOCRCs have more aggressive histopathological features with somatic mutations resulting in pro-inflammatory tumor microenvironments. There is a tendency to treat EOCRCs with multimodal chemotherapeutic regimens and more extensive surgery than LOCRCs with conflicting postoperative outcomes and survival data. Current research is limited by a lack of Australasian studies, retrospective study designs, and heterogeneous definitions of EOCRC. Future research should address these and focus on investigating the role of immunotherapies, establishing minimally invasive diagnostic biomarkers and nomograms, and evaluating the survival and functional outcomes of EOCRC.

Benefits and harms of prostate specific antigen testing according to Australian guidelines

Guidelines for prostate specific antigen (PSA) testing in Australia recommend that men at average risk of prostate cancer who have been informed of the benefits and harms, and who decide to undergo regular testing, should be offered testing every 2 years from 50 to 69 years. This study aimed to estimate the benefits and harms of regular testing in this context. We constructed Policy1-Prostate, a discrete event microsimulation platform of the natural history of prostate cancer and prostate cancer survival, and PSA testing patterns and subsequent management in Australia. The model was calibrated to pre-PSA (before 1985) prostate cancer incidence and mortality and validated against incidence and mortality trends from 1985 to 2011 and international trials. The model predictions were concordant with trials and Australian observed incidence and mortality data from 1985 to 2011. Out of 1000 men who choose to test according to the guidelines, 36 [21-41] men will die from prostate cancer and 126 [119-133] men will be diagnosed with prostate cancer, compared with 50 [47-54] and 94 [90-98] men who do not test, respectively. During the 20 years of active PSA testing, 32.3% [25.6%-38.8%] of all PSA-test detected cancers are overdiagnosed cases that is, 30 [21-42] out of 94 [83-107] PSA-test detected cancers. Australian men choosing to test with PSA every two years from 50 to 69 will reduce their risk of ever dying from prostate cancer and incur a risk of overdiagnosis: for every man who avoids dying from prostate cancer, two will be overdiagnosed with prostate cancer between 50 and 69 years of age. Australian men, with health professionals, can use these results to inform decision-making about PSA testing.

Comprehensive Analysis of Early-onset Colorectal Cancer: A Review

Early-onset colorectal cancer (CRC), which refers to CRC diagnosed in individuals below the age of 50 years, is a growing health concern that presents unique challenges in diagnosis, treatment, and long-term outcomes. Although approximately 70% of early-onset CRC cases are sporadic, with no apparent family history, approximately 25% have a familial component, and up to 20% may be associated with germline mutations, indicating a higher prevalence compared with the general population. Despite the progress in identifying the environmental, molecular, and genetic risk factors of early-onset CRC, the underlying causes for the global increase in its incidence remain unclear. This comprehensive review aims to provide a thorough analysis of early-onset CRC by examining the trends associated with its incidence, clinical and pathological characteristics, risk factors, molecular and genetic profiles, prognosis and screening strategies. By deepening our understanding of early-onset CRC, significant advances related to improving the outcomes and alleviating the burden of this disease on individuals, families, and healthcare systems can be achieved.

Young-onset colorectal cancer

In the past decades the incidence of colorectal cancer (CRC) in people under the age of 50 years has increased, which is referred to as early-onset CRC or young-onset CRC (YO-CRC). YO-CRC is expected to account for 11% of colon cancers and 23% of rectal cancers by 2030. This trend is observed in different parts of the world and in both men and women. In 20% of patients with YO-CRC, a hereditary cancer syndrome is found as the underlying cause; however, in the majority of patients no genetic predisposition is present. Beginning in the 1950s, major changes in lifestyle such as antibiotic use, low physical activity and obesity have affected the gut microbiome and may be an important factor in YO-CRC development. Owing to a lack of screening, patients with YO-CRC are often diagnosed with advanced-stage disease. Long-term treatment-related complications should be taken into account in these younger patients, making the more traditional sequential approaches of drug therapy not always the most appropriate option. To better understand the underlying mechanism and define relationships between environmental factors and YO-CRC development, long-term prospective studies are needed with lifestyle data collected from childhood.

Effectiveness of Colorectal Cancer (CRC) Screening on All-Cause and CRC-Specific Mortality Reduction: A Systematic Review and Meta-Analysis

(1) Background: The aim of this study was to pool and compare all-cause and colorectal cancer (CRC) specific mortality reduction of CRC screening in randomized control trials (RCTs) and simulation models, and to determine factors that influence screening effectiveness. (2) Methods: PubMed, Embase, Web of Science and Cochrane library were searched for eligible studies. Multi-use simulation models or RCTs that compared the mortality of CRC screening with no screening in general population were included. CRC-specific and all-cause mortality rate ratios and 95% confidence intervals were calculated by a bivariate random model. (3) Results: 10 RCTs and 47 model studies were retrieved. The pooled CRC-specific mortality rate ratios in RCTs were 0.88 (0.80, 0.96) and 0.76 (0.68, 0.84) for guaiac-based fecal occult blood tests (gFOBT) and single flexible sigmoidoscopy (FS) screening, respectively. For the model studies, the rate ratios were 0.45 (0.39, 0.51) for biennial fecal immunochemical tests (FIT), 0.31 (0.28, 0.34) for biennial gFOBT, 0.61 (0.53, 0.72) for single FS, 0.27 (0.21, 0.35) for 10-yearly colonoscopy, and 0.35 (0.29, 0.42) for 5-yearly FS. The CRC-specific mortality reduction of gFOBT increased with higher adherence in both studies (RCT: 0.78 (0.68, 0.89) vs. 0.92 (0.87, 0.98), model: 0.30 (0.28, 0.33) vs. 0.92 (0.51, 1.63)). Model studies showed a 0.62-1.1% all-cause mortality reduction with single FS screening. (4) Conclusions: Based on RCTs and model studies, biennial FIT/gFOBT, single and 5-yearly FS, and 10-yearly colonoscopy screening significantly reduces CRC-specific mortality. The model estimates are much higher than in RCTs, because the simulated biennial gFOBT assumes higher adherence. The effectiveness of screening increases at younger screening initiation ages and higher adherences.

Colon and rectal cancer treatment patterns and their associations with clinical, sociodemographic and lifestyle characteristics: analysis of the Australian 45 and Up Study cohort

BACKGROUND

Colorectal cancer is the third most diagnosed cancer globally and the second leading cause of cancer death. We examined colon and rectal cancer treatment patterns in Australia.

METHODS

From cancer registry records, we identified 1,236 and 542 people with incident colon and rectal cancer, respectively, diagnosed during 2006-2013 in the 45 and Up Study cohort (267,357 participants). Cancer treatment and deaths were determined via linkage to routinely collected data, including hospital and medical services records. For colon cancer, we examined treatment categories of "surgery only", "surgery plus chemotherapy", "other treatment" (i.e. other combinations of surgery/chemotherapy/radiotherapy), "no record of cancer-related treatment, died"; and, for rectal cancer, "surgery only", "surgery plus chemotherapy and/or radiotherapy", "other treatment", and "no record of cancer-related treatment, died". We analysed survival, time to first treatment, and characteristics associated with treatment receipt using competing risks regression.

RESULTS

86.4% and 86.5% of people with colon and rectal cancer, respectively, had a record of receiving any treatment ≤2 years post-diagnosis. Of those treated, 93.2% and 90.8% started treatment ≤2 months post-diagnosis, respectively. Characteristics significantly associated with treatment receipt were similar for colon and rectal cancer, with strongest associations for spread of disease and age at diagnosis (p<0.003). For colon cancer, the rate of "no record of cancer-related treatment, died" was higher for people with distant spread of disease (versus localised, subdistribution hazard ratio (SHR)=13.6, 95% confidence interval (CI):5.5-33.9), age ≥75 years (versus age 45-74, SHR=3.6, 95%CI:1.8-7.1), and visiting an emergency department ≤1 month pre-diagnosis (SHR=2.9, 95%CI:1.6-5.2). For rectal cancer, the rate of "surgery plus chemotherapy and/or radiotherapy" was higher for people with regional spread of disease (versus localised, SHR=5.2, 95%CI:3.6-7.7) and lower for people with poorer physical functioning (SHR=0.5, 95%CI:0.3-0.8) or no private health insurance (SHR=0.7, 95%CI:0.5-0.9).

CONCLUSION

Before the COVID-19 pandemic, most people with colon or rectal cancer received treatment ≤2 months post-diagnosis, however, treatment patterns varied by spread of disease and age. This work can be used to inform future healthcare requirements, to estimate the impact of cancer control interventions to improve prevention and early diagnosis, and serve as a benchmark to assess treatment delays/disruptions during the pandemic. Future work should examine associations with clinical factors (e.g. performance status at diagnosis) and interdependencies between characteristics such as age, comorbidities, and emergency department visits.

Guidance for setting international standards on reporting longitudinal adherence to stool-based colorectal cancer screening

Longitudinal adherence to colorectal cancer (CRC) screening is reported using different summarizing measures, which hampers international comparison. We provide evidence to guide recommendations on which longitudinal adherence measure to report. Using adherence data over four stool-based CRC screening rounds in three countries, we calculated six summarizing adherence measures; adherence over all rounds, adherence per round, rescreening, full programme adherence (yes/no), regularity (never/inconsistent/consistent screenees) and number of times participated. For each measure, we calculated the accuracy in capturing the observed adherence patterns. Using the ASCCA model, we predicted screening effectiveness when using summarizing measures as model input versus the observed adherence patterns. Adherence over all rounds in the Italian, Spanish and Dutch cohorts was 64.9%, 42.8% and 61.5%, respectively, and the proportion of consistent screenees was 50.9%, 26.3% and 45.7%. Number of times participated and regularity were most accurate and resulted in similar model-predicted screening effectiveness as simulating the observed adherence patterns of Italy, Spain and the Netherlands (mortality reductions: 24.4%, 16.9% and 23.5%). Adherence over all rounds and adherence per round were least accurate. Screening effectiveness was overestimated when using adherence over all rounds (mortality reductions: 26.8%, 19.4% and 25.7%) and adherence per round (mortality reductions: 26.8%, 19.5% and 25.9%). To conclude, number of times participated and regularity were most accurate and resulted in similar model-predicted screening effectiveness as using the observed adherence patterns. However they require longitudinal data. To facilitate international comparison of CRC screening programme performance, consensus on an accurate adherence measure to report should be reached.

Third Asia-Pacific consensus recommendations on colorectal cancer screening and postpolypectomy surveillance

The Asia-Pacific region has the largest number of cases of colorectal cancer (CRC) and one of the highest levels of mortality due to this condition in the world. Since the publishing of two consensus recommendations in 2008 and 2015, significant advancements have been made in our knowledge of epidemiology, pathology and the natural history of the adenoma-carcinoma progression. Based on the most updated epidemiological and clinical studies in this region, considering literature from international studies, and adopting the modified Delphi process, the Asia-Pacific Working Group on Colorectal Cancer Screening has updated and revised their recommendations on (1) screening methods and preferred strategies; (2) age for starting and terminating screening for CRC; (3) screening for individuals with a family history of CRC or advanced adenoma; (4) surveillance for those with adenomas; (5) screening and surveillance for sessile serrated lesions and (6) quality assurance of screening programmes. Thirteen countries/regions in the Asia-Pacific region were represented in this exercise. International advisors from North America and Europe were invited to participate.

Incidence trends for twelve cancers in younger adults-a rapid review

Many cancer referral guidelines use patient’s age as a key criterium to decide who should be referred urgently. A recent rise in the incidence of colorectal cancer in younger adults has been described in high-income countries worldwide. Information on other cancers is more limited. The aim of this rapid review was to determine whether other cancers are also increasing in younger age groups, as this may have important implications for prioritising patients for investigation and referral. We searched MEDLINE, Embase and Web of Science for studies describing age-related incidence trends for colorectal, bladder, lung, oesophagus, pancreas, stomach, breast, ovarian, uterine, kidney and laryngeal cancer and myeloma. ‘Younger’ patients were defined based on NICE guidelines for cancer referral. Ninety-eight studies met the inclusion criteria. Findings show that the incidence of colorectal, breast, kidney, pancreas, uterine cancer is increasing in younger age groups, whilst the incidence of lung, laryngeal and bladder cancer is decreasing. Data for oesophageal, stomach, ovarian cancer and myeloma were inconclusive. Overall, this review provides evidence that some cancers are increasingly being diagnosed in younger age groups, although the mechanisms remain unclear. Cancer investigation and referral guidelines may need updating in light of these trends.

Implications of the United States recommendations for early-age-at-onset colorectal cancer screening in Canada

The United States Preventive Services Task Force (USPSTF) recently issued an updated recommendation for population-based colorectal cancer (CRC) screening starting at age 45, due to a sustained increase in the incidence of early-age-at-onset CRC (eoCRC). A similar increase in the incidence of eoCRC has been observed in Canada since the early 2000s. However, the inherent differences between the US and Canadian health care systems with many different reimbursement and capacity considerations limit the applicability of the recommendations to the Canadian context. In order to facilitate further discussion around Canadian guidelines and recommendations, several research gaps need to be addressed: 1) a detailed understanding of trends in histology, topography, initial stage at diagnosis, and mortality among eoCRC; 2) a detailed analysis of cost-effectiveness outlining the impacts to the current screening programs with potential harms and benefits; 3) a comprehensive understanding of risk factor profiles that may lead to meaningful recommendations for screening decisions within the 40-49 age group in the absence of wide-spread screening programs; and 4) an evaluation of the effectiveness of current and novel screening tests or biomarkers specifically in the 40-49 age group. In the meantime, we suggest that physicians and patients begin discussions about screening at age 45 by reviewing family history and alerting patients to symptoms of CRC, which may increase screening adherence at age 50. This issue will remain an active area of debate with Canada as a careful laggard in changing recommendations, while attempting to balance system considerations with eoCRC trends and patient outcomes.

Clinical and molecular profile of young adults with early-onset colorectal cancer: Experience from four Australian tertiary centers

BACKGROUND

Patients with early-onset colorectal cancer (EO-CRC) have unique characteristics. Contemporary data on the pathological and molecular features, and survival of EO-CRC are limited in the Australian context.

AIM

To determine the demographic, histopathological and molecular characteristics of adults with EO-CRC, and their survival.

METHODS

We conducted a retrospective study of adults aged 18-49 years with EO-CRC who were referred to the Illawarra Shoalhaven Local Health District, South Eastern Sydney Local Health District and Royal North Shore Hospital in New South Wales, Australia, between 2014 and 2018.

RESULTS

Of 257 patients included, 94 (37%) patients presented with de novo metastatic CRC, 80% patients had near-average risk family history and 89% had a symptomatic presentation. In 159 patients with nonmetastatic disease at diagnosis, stage III disease (OR 3.88 [95% CI: 1.13-13.3]; p = .03) and the presence of perineural invasion (PNI) (OR 6.63 [95% CI: 2.21-19.84]; p = .001) were risk factors associated with the development of metastatic disease. Among 94 patients with de novo metastatic disease, 43 (43%) and 12 (14%) patients harbored a KRAS or BRAF V600E mutation, respectively. The median overall survival was 29.6 months (95% CI: 20.4-38.7). BRAF mutation was associated with inferior survival (HR 3.00 [95% CI: 1.30-6.94]; p = .01).

CONCLUSION

The prevalence of KRAS and BRAF mutations in our cohort is similar to the overseas experience. Stage III disease at diagnosis, presence of PNI and BRAF mutation are adverse prognostic indicators. A better understanding of the molecular landscape is needed for this patient cohort, so as to better tailor prevention strategies, screening and treatment pathways.

Health system costs and days in hospital for colorectal cancer patients in New South Wales, Australia

Introduction

Colorectal cancer (CRC) care costs the Australian healthcare system more than any other cancer. We estimated costs and days in hospital for CRC cases, stratified by site (colon/rectal cancer) and disease stage, to inform detailed analyses of CRC-related healthcare.

Methods

Incident CRC patients were identified using the Australian 45 and Up Study cohort linked with cancer registry records. We analysed linked hospital admission records, emergency department records, and reimbursement records for government-subsidised medical services and prescription medicines. Cases’ health system costs (2020 Australian dollars) and hospital days were compared with those for cancer-free controls (matched by age, sex, geography, smoking) to estimate excess resources by phase of care, analysed by sociodemographic, health, and disease characteristics.

Results

1200 colon and 546 rectal cancer cases were diagnosed 2006–2013, and followed up to June 2016. Eighty-nine percent of cases had surgery, chemotherapy or radiotherapy, and excess costs were predominantly for hospitalisations. Initial phase (12 months post-diagnosis) mean excess health system costs were $50,434 for colon and $60,877 for rectal cancer cases, with means of 16 and 18.5 excess hospital days, respectively. The annual continuing mean excess costs were $6,779 (colon) and $8,336 (rectal), with a mean of 2 excess hospital days each. Resources utilised (costs and days) in these phases increased with more advanced disease, comorbidities, and younger age. Mean excess costs in the year before death were $74,952 (colon) and $67,733 (rectal), with means of 34 and 30 excess hospital days, respectively–resources utilised were similar across all characteristics, apart from lower costs for cases aged ≥75 at diagnosis.

Conclusions

Health system costs and hospital utilisation for CRC care are greater for people with more advanced disease. These findings provide a benchmark, and will help inform future cost-effectiveness analyses of potential approaches to CRC screening and treatment.

Using Metamodeling to Identify the Optimal Strategy for Colorectal Cancer Screening

OBJECTIVES

Metamodeling can address computational challenges within decision-analytic modeling studies evaluating many strategies. This article illustrates the value of metamodeling for evaluating colorectal cancer screening strategies while accounting for colonoscopy capacity constraints.

METHODS

In a traditional approach, the best screening strategy was identified from a limited subset of strategies evaluated with the validated Adenoma and Serrated pathway to Colorectal CAncer model. In a metamodeling approach, metamodels were fitted to this limited subset to evaluate all potentially plausible strategies and determine the best overall screening strategy. Approaches were compared based on the best screening strategy in life-years gained compared with no screening. Metamodel runtime and accuracy was assessed.

RESULTS

The metamodeling approach evaluated >40 000 strategies in <1 minute with high accuracy after 1 adaptive sampling step (mean absolute error: 0.0002 life-years) using 300 samples in total (generation time: 8 days). Findings indicated that health outcomes could be improved without requiring additional colonoscopy capacity. Obtaining similar insights using the traditional approach could require at least 1000 samples (generation time: 28 days). Suggested benefits from screening at ages <40 years require adequate validation of the underlying Adenoma and Serrated pathway to Colorectal CAncer model before making policy recommendations.

CONCLUSIONS

Metamodeling allows rapid assessment of a vast set of strategies, which may lead to identification of more favorable strategies compared to a traditional approach. Nevertheless, metamodel validation and identifying extrapolation beyond the support of the original decision-analytic model are critical to the interpretation of results. The screening strategies identified with metamodeling support ongoing discussions on decreasing the starting age of colorectal cancer screening.

Validation of Microsimulation Models against Alternative Model Predictions and Long-Term Colorectal Cancer Incidence and Mortality Outcomes of Randomized Controlled Trials

Background. This study aimed to assess the validity of 2 microsimulation models of colorectal cancer (CRC), Policy1-Bowel and ASCCA. Methods. The model-estimated CRC risk in population subgroups with different health statuses, "dwell time" (time from incident precancerous polyp to symptomatically detected CRC), and reduction in symptomatically detected CRC incidence after a one-time complete removal of polyps and/or undetected CRC were compared with published findings from 3 well-established models (MISCAN, CRC-SPIN, and SimCRC). Furthermore, 6 randomized controlled trials (RCTs) that provided screening using a guaiac fecal occult blood test (Funen trial, Burgundy trial, and Minnesota Colon Cancer Control Study [MCCCS]) or flexible sigmoidoscopy (NORCCAP, SCORE, and UKFSST) with long-term follow-up were simulated. Model-estimated long-term relative reductions of CRC incidence (RR_inc) and mortality (RR_mort) were compared with the RCTs' findings. Results. The Policy1-Bowel and ASCCA estimates showed more similarities to CRC-SPIN and SimCRC. For example, overall dwell times estimated by Policy1-Bowel (24.0 years) and ASCCA (25.3) were comparable to CRC-SPIN (25.8) and SimCRC (25.2) but higher than MISCAN (10.6). In addition, ∼86% of Policy1-Bowel's and ∼74% of ASCCA's estimated RR_inc and RR_mort were consistent with the RCTs' long-term follow-up findings. For example, at 17 to 18 years of follow-up, the MCCCS reported RR_mort of 0.67 (95% confidence interval [CI], 0.51-0.83) and 0.79 (95% CI, 0.62-0.97) for the annual and biennial screening arm, respectively, and the UKFSST reported RR_mort of 0.70 (95% CI, 0.62-0.79) for CRC at all sites and 0.54 (95% CI, 0.46-0.65) for distal CRC. The corresponding model estimates were 0.65, 0.74, 0.81, and 0.61, respectively, for Policy1-Bowel and 0.65, 0.70, 0.75, and 0.58, respectively, for ASCCA. Conclusion. Policy1-Bowel and ASCCA's estimates are largely consistent with the data included for comparisons, which indicates good model validity.

Cost-Effectiveness of Current Colorectal Cancer Screening Tests

Cost-effectiveness analysis compares benefits and costs of different interventions to inform decision makers. Alternatives are compared based on an incremental cost-effectiveness ratio reported in terms of cost per quality-adjusted life-year gained. Multiple cost-effectiveness analyses of colorectal cancer (CRC) screening have been performed. Although regional epidemiology of CRC, relevant screening strategies, regional health system, and applicable medical costs in local currencies differ by country and region, several overarching points emerge from literature on cost-effectiveness of CRC screening. Cost-effectiveness analysis informs decisions in ongoing debates, including preferred age to begin average-risk CRC screening, and implementation of CRC screening tailored to predicted CRC risk.

Pathways to a cancer-free future: a protocol for modelled evaluations to minimise the future burden of colorectal cancer in Australia

INTRODUCTION

With almost 50% of cases preventable and the Australian National Bowel Cancer Screening Program in place, colorectal cancer (CRC) is a prime candidate for investment to reduce the cancer burden. The challenge is determining effective ways to reduce morbidity and mortality and their implementation through policy and practice. Pathways-Bowel is a multistage programme that aims to identify best-value investment in CRC control by integrating expert and end-user engagement; relevant evidence; modelled interventions to guide future investment; and policy-driven implementation of interventions using evidence-based methods. METHODS AND ANALYSIS: Pathways-Bowel is an iterative work programme incorporating a calibrated and validated CRC natural history model for Australia (Policy1-Bowel) and assessing the health and cost outcomes and resource use of targeted interventions. Experts help identify and prioritise modelled evaluations of changing trends and interventions and critically assess results to advise on their real-world applicability. Where appropriate the results are used to support public policy change and make the case for optimal investment in specific CRC control interventions. Fourteen high-priority evaluations have been modelled or planned, including evaluations of CRC outcomes from the changing prevalence of modifiable exposures, including smoking and body fatness; potential benefits of daily aspirin intake as chemoprevention; increasing CRC incidence in people aged <50 years; increasing screening participation in the general and Aboriginal and Torres Strait Islander populations; alternative screening technologies and modalities; and changes to follow-up surveillance protocols. Pathways-Bowel is a unique, comprehensive approach to evaluating CRC control; no prior body of work has assessed the relative benefits of a variety of interventions across CRC development and progression to produce a list of best-value investments.

ETHICS AND DISSEMINATION

Ethics approval was not required as human participants were not involved. Findings are reported in a series of papers in peer-reviewed journals and presented at fora to engage the community and policymakers.

Demographic trends in the incidence of young-onset colorectal cancer: a population-based study

Background

Evidence is emerging that the incidence of colorectal cancer is increasing in young adults, but the descriptive epidemiology required to better understand these trends is currently lacking.

Methods

A population‐based cohort study was carried out including all adults aged 20–49 years diagnosed with colorectal cancer in England between 1974 and 2015. Data were extracted from the National Cancer Registration and Analysis Service database using ICD‐9/10 codes for colorectal cancer. Temporal trends in age‐specific incidence rates according to sex, anatomical subsite, index of multiple deprivation quintile and geographical region were analysed using Joinpoint regression.

Results

A total of 56 134 new diagnoses of colorectal cancer were analysed. The most sustained increase in incidence rate was in the group aged 20–29 years, which was mainly driven by a rise in distal tumours. The magnitude of incident rate increases was similar in both sexes and across Index of Multiple Deprivation quintiles, although the most pronounced increases in incidence occurred in the southern regions of England.

Conclusion

Colorectal cancer should no longer be considered a disease of older people. Changes in incidence rates should be used to inform future screening policy, preventative strategies and research agendas, as well as increasing public understanding that younger people need to be aware of the symptoms of colorectal cancer.

Improving Australian National Bowel Cancer Screening Program outcomes through increased participation and cost-effective investment

BACKGROUND

The Australian National Bowel Cancer Screening Program (NBCSP) provides biennial immunochemical faecal occult blood test (iFOBT) screening for people aged 50-74 years. Previous work has quantified the number of colorectal cancer (CRC) deaths prevented by the NBCSP and has shown that it is cost-effective. With a 40% screening participation rate, the NBCSP is currently underutilised and could be improved by increasing program participation, but the maximum appropriate level of spending on effective interventions to increase adherence has not yet been quantified.

OBJECTIVES

To estimate (i) reductions in CRC cases and deaths for 2020-2040 attributable to, and (ii) the threshold for cost-effective investment (TCEI) in, effective future interventions to improve participation in the NBCSP.

METHODS

A comprehensive microsimulation model, Policy1-Bowel, was used to simulate CRC natural history and screening in Australia, considering currently reported NBCSP adherence rates, i.e. iFOBT participation (∼40%) and diagnostic colonoscopy assessment rates (∼70%). Australian residents aged 40-74 were modelled. We evaluated three scenarios: (1) diagnostic colonoscopy assessment increasing to 90%; (2) iFOBT screening participation increasing to 60% by 2020, 70% by 2030 with diagnostic assessment rates of 90%; and (3) iFOBT screening increasing to 90% by 2020 with diagnostic assessment rates of 90%. In each scenario, we estimated CRC incidence and mortality, colonoscopies, costs, and TCEI given indicative willingness-to-pay thresholds of AUD$10,000-$30,000/LYS.

RESULTS

By 2040, age-standardised CRC incidence and mortality rates could be reduced from 46.2 and 13.5 per 100,000 persons, respectively, if current participation rates continued, to (1) 44.0 and 12.7, (2) 36.8 and 8.8, and (3) 31.9 and 6.5. In Scenario 2, 23,000 lives would be saved from 2020-2040 vs current participation rates. The estimated scenario-specific TCEI (Australian dollars or AUD$/year) to invest in interventions to increase participation, given a conservative willingness-to-pay threshold of AUD$10,000/LYS, was (1) AUD$14.9M, (2) AUD$72.0M, and (3) AUD$76.5M.

CONCLUSION

Significant investment in evidence-based interventions could be used to improve NBCSP adherence and help realise the program's potential. Such interventions might include mass media campaigns to increase program participation, educational or awareness interventions for practitioners, and/or interventions resulting in improvements in referral pathways. Any set of interventions which achieves at least 70% iFOBT screening participation and a 90% diagnostic assessment rate while costing under AUD$72 million annually would be highly cost-effective (<AUD$10,000/LYS) and save 23,000 additional lives from 2020-2040.

National Trends in Colorectal Cancer Incidence Among Older and Younger Adults in Canada

IMPORTANCE

Recent evidence has shown that although the incidence of colorectal cancer (CRC) is decreasing among older adults, rates have increased in adults younger than 50 years. Given that younger adults are typically classified as at low risk for the disease, this epidemiologic shift is cause for concern.

OBJECTIVE

To analyze Canadian national cancer incidence registries to determine incidence trends for CRC among older and younger adults, updated to 2015.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study determined the incidence of CRC using data from the National Cancer Incidence Reporting System (1969-1992) and the Canadian Cancer Registry (1992-2015). All Canadians diagnosed with CRC from January 1, 1969, through December 31, 2015, were included in this study. Trends among men and women were examined separately and by age category (>50 vs <50 years). Birth cohort models were fit using 5-year groups starting in 1886, with 1936 as the reference cohort. Data were analyzed from May 13, 2018 to May 16, 2018.

MAIN OUTCOMES AND MEASURES

Annualized percentage changes and incidence rate ratios of CRC.

RESULTS

From 1971 to 2015, 688 515 incident cases (52.9% women) of CRC were identified. Although the incidence of CRC has decreased in older men and women, rates among younger men and women have increased since 2006 and 2010, respectively. For women younger than 50 years, incidence has increased with a mean annual percentage change of 4.45% since 2010; for men younger than 50 years, a mean annual percentage change of 3.47% from 2006 through 2015. There was an association between CRC incidence and birth cohort, with more recent cohorts being at greater risk than those born earlier. For men, the risk of colorectal cancer in the youngest cohort is more than double that of the reference (incidence rate ratio, 2.57; 95% CI, 1.32-5.02). Incidence rate ratios were not significant for women (IRR, 2.12; 95% CI, 0.95-4.70) but increased in successively younger cohorts.

CONCLUSIONS AND RELEVANCE

This study found increasing incidence of colorectal cancer diagnoses among Canadian men and women younger than 50 years of age. This increase in incidence among a low-risk population calls for additional research on possible risk factors that may be affecting these younger cohorts. It appears that primary prevention should be the highest priority to reduce the number of younger adults developing CRC in the future.