CT colonography: accuracy, acceptance, safety and position in organised population screening

SYL3C Aptamer-DNA Tetrahedra Conjugates Enable Near-Infrared Fluorescent Imaging of Colorectal Cancer

Purpose

SYL3C is an optimized DNA aptamer with high selectivity and affinity for the epithelial cell adhesion molecule (EpCAM), an overexpressed tumor antigen in colorectal cancer (CRC). While its cellular affinity has been validated, in vivo studies are lacking.

Methods

This study modifies SYL3C with the fluorescent motif Cy7 to evaluate its metabolism and diagnostic potential in EpCAM-positive HT-29 xenograft mice using near-infrared fluorescence (NIRF). We also employ DNA Tetrahedra (DTN) to load the Cy7-DTN-SYL3C probe and assess whether this strategy improves circulation and tumor uptake of SYL3C.

Results

Cy7-SYL3C is primarily metabolized by the kidneys and enables targeted imaging of HT-29 tumors, outperforming untargeted Cy7-DTN. The DTN coupling strategy prolongs SYL3C metabolism and enhances tumor probe uptake about twice higher than Cy7-SYL3C over 24 hours.

Conclusion

This study presents preliminary evidence for the SYL3C aptamer's potential in vivo imaging of EpCAM-positive CRC. The DTN conjugation strategy may extend the aptamer's metabolic stability and improve tumor uptake, expanding its applications in CRC diagnosis and treatment.

Sociodemographic Factors and Screening CT Colonography Use Among Medicare Beneficiaries

BACKGROUND. Approximately one-third of the eligible U.S. population have not undergone guideline-compliant colorectal cancer (CRC) screening. Guidelines recognize various screening strategies to increase adherence. CMS provides coverage for all recommended screening tests except CT colonography (CTC). OBJECTIVE. The purpose of this study was to compare CTC and other CRC screening tests in terms of associations of utilization with income, race and ethnicity, and urbanicity in Medicare fee-for-service beneficiaries. METHODS. This retrospective study used CMS Research Identifiable Files from January 1, 2011, through December 31, 2020. These files contain claims information for 5% of Medicare fee-for-service beneficiaries. Data were extracted for individuals 45-85 years old, and individuals with high CRC risk were excluded. Multivariable logistic regression models were constructed to determine the likelihood of undergoing CRC screening tests (as well as of undergoing diagnostic CTC, a CMS-covered test with similar physical access as screening CTC) as a function of income, race and ethnicity, and urbanicity while controlling for sex, age, Charlson comorbidity index, U.S. census region, screening year, and related conditions and procedures. RESULTS. For 12,273,363 beneficiary years (mean age, 70.5 ± 8.2 [SD] years; 2,436,849 unique beneficiaries: 6,774,837 female beneficiaries, 5,498,526 male beneficiaries), there were 785,103 CRC screenings events, including 645 for screening CTC. Compared with individuals living in communities with per capita income of less than US$25,000, individuals in communities with income of US$100,000 or more had OR for undergoing screening CTC of 5.73, optical colonoscopy (OC) of 1.36, sigmoidoscopy of 1.03, guaiac fecal occult blood test or fecal immunochemical test of 1.50, stool DNA of 1.43, and diagnostic CTC of 2.00. The OR for undergoing screening CTC was 1.00 for Hispanic individuals and 1.08 for non-Hispanic Black individuals compared with non-Hispanic White individuals. Compared with the OR for undergoing screening CTC for residents of metropolitan areas, the OR was 0.51 for residents of micropolitan areas and 0.65 for residents of small or rural areas. CONCLUSION. The association with income was substantially larger for screening CTC than for other CRC screening tests or for diagnostic CTC. CLINICAL IMPACT. Medicare's noncoverage for screening CTC may contribute to lower adherence with CRC screening guidelines for lower-income beneficiaries. Medicare coverage of CTC could reduce income-based disparities for individuals avoiding OC owing to invasiveness, need for anesthesia, or complication risk.

Comparison of MiraLAX and magnesium citrate for bowel preparation at CT colonography

PURPOSE

To compare MiraLAX, a hypo-osmotic lavage, and magnesium citrate (MgC), a hyper-osmotic agent for bowel preparation at CTC.

METHODS

398 total screening CTC studies were included in this retrospective, single institution study. 297 underwent preparation with a double-dose MgC regimen (mean age, 61 ± 5.5 years; 142 male/155 female) and 101 with 8.3 oz (equivalent to 238 g PEG) of MiraLAX (mean age, 60 ± 9.6 years; 45 male/56 female). Oral contrast for tagging purposes was utilized in both regimens. Studies were retrospectively analyzed for residual fluid volume and attenuation by automated analysis, as well for subjective oral contrast coating of the normal colonic wall and polyps. 50 patients underwent successive CTC studies utilizing each agent (mean, 6.1 ± 1.7 years apart), allowing for intra-patient comparison. Chi-squared, Fisher's exact, McNemar, and t-tests were used for data comparison.

RESULTS

Residual fluid volume (as percentage of total colonic volume) and fluid density was 7.2 ± 4.2% and 713 ± 183 HU for the MgC cohort and 8.7 ± 3.8% and 1044 HU ± 274 for the MiraLAX cohort, respectively (p = 0.001 and p < 0.001, respectively). Similar results were observed for the intra-patient cohort. Colonic wall coating negatively influencing interpretation was noted in 1.7% of MgC vs. 6.9% of MiraLAX examinations (p = 0.008). Polyps were detected in 12% of all MgC vs. 16% of all MiraLAX CTCs (p = 0.29).

CONCLUSION

CTC bowel preparation with the hypo-osmotic MiraLAX agent appears to provide acceptable diagnostic quality that is comparable to the hyper-osmotic MgC agent, especially when factoring in patient safety and tolerance.

Detection methods of synchronous colorectal lesions in proximal colon for patients with obstructive colorectal cancer: a literature review

INTRODUCTION

Colorectal cancer holds a high morbidity and mortality rate. As a common method for colorectal cancer detection, colonoscopy has difficulty in passing through the malignant stenosis in patients with obstructive colorectal cancer, which results in incomplete detection and missed diagnosis. The missed synchronous lesions increase the risk of metachronous cancer. Therefore, detecting proximal synchronous lesions in patients with obstructive colorectal cancer should be appreciated before operation.

AREA COVERED

This review evaluates related literature, aiming at providing clinicians with more ideas and attention for detecting proximal synchronous lesions in patients with obstructive colorectal cancer.

EXPERT OPINION

In patients with obstructive colorectal cancer, missed diagnosis of lesions proximal to the obstruction may lead to metachronous colorectal cancer. Except for preoperative colonoscopy which is difficult to pass through malignant stenosis, other methods that can evaluate proximal colon segment are critical. This article introduced several preoperative, intraoperative and postoperative measures for synchronous lesions detection. The choice of methods should base on patients' conditions, aiming at a high diagnostic yield and low risk. Early detection and resection of synchronous lesions in the proximal section of malignant obstruction are expected to minimize the risk of metachronous colorectal cancer and even effect follow-up treatment strategy, which deserves the attention of clinicians.

Evaluation of vascular anatomy for colon cancer located in the splenic flexure using the preoperative three-dimensional computed tomography angiography with colonography

PURPOSE

The aim of this study is to reveal the vascular branching variation in SFC (splenic flexure cancer) patients using the preoperative three-dimensional computed tomography angiography with colonography (3D-CTAC).

METHODS

We retrospectively analyzed patients with SFC who underwent preoperative 3D-CTAC between January 2014 and December 2019.

RESULTS

Among 1256 colorectal cancer (CRC) patients, 96 (7.6%) manifested SFC. The arterial branching from the superior mesenteric artery (SMA) was classified into five patterns, as follows: (type 1A) the left branch of middle colic artery (LMCA) diverged from middle colic artery (MCA) (N = 47, 49.0%); (2A) the LMCA diverged from the MCA and the accessory middle colic artery (AMCA) (N = 26, 27.1%); (3A) the LMCA independently diverged from the SMA (N = 16, 16.7%); (4A) the LMCA independently diverged from the SMA and AMCA (N = 3, 3.1%); (5A) only the AMCA and the LMCA was absent (N = 4, 4.1%). Venous drainage was classified into four patterns, as follows: (type 1V) the SFV flows into the inferior mesenteric vein (IMV) then back to the splenic vein (N = 50, 52.1%); (2V) the SFV flows into the IMV then back to the superior mesenteric vein (SMV) (N = 19, 19.8%); (type 3V) the SFV independently flows into the splenic vein (N = 3, 3.1%); (type 4V) the SFV is absent (N = 24, 25.0%).

CONCLUSION

3D-CTAC could reveal accurate preoperative tumor localization and vascular branching. These classifications should be helpful in performing accurate complete mesocolic excision and central vessel ligation for SFC.

Long noncoding RNA LINC02418 regulates MELK expression by acting as a ceRNA and may serve as a diagnostic marker for colorectal cancer

Some types of long noncoding RNAs (lncRNAs) are aberrantly expressed in human diseases, including cancer. However, the overall biological roles and clinical significances of most lncRNAs in colorectal cancer (CRC) are not fully understood. First, The Cancer Genome Atlas (TCGA) was analyzed to identify differentially expressed lncRNAs between CRC tissues and noncancerous tissues. We identified that LINC02418 was highly expressed in CRC tissues and cell lines. Next, we evaluated the effect of LINC02418 on CRC tumorigenesis and its regulatory functions of absorbing microRNA and indirectly stimulating protein expression by acting as a ceRNA. Mechanistically, LINC02418 acted as a ceRNA to upregulate MELK expression by absorbing miR-1273g-3p. In addition, the diagnostic performance of cell-free LINC02418 and exosomal LINC02418 were both evaluated by the receiver operating characteristic curve and the area under the curve (AUC). Exosomal LINC02418 could distinguish the patients with CRC from the healthy controls (AUC = 0.8978, 95% confidence interval = 0.8644–0.9351) better than cell-free LINC02418 (AUC = 0.6784, 95% confidence interval = 0.6116–0.7452). Collectively, we determined that LINC02418 was significantly overexpressed in CRC and that the LINC02418–miR-1273g-3p–MELK axis played a critical role in CRC tumorigenesis. Finally, exosomal LINC02418 is a promising, novel biomarker that can be used for the clinical diagnosis of CRC.

The detection of interval colorectal cancers following screening by fecal immunochemical test may predict worse outcomes and prompt ethical concerns: a 6-year population-based cohort study in a full district

The rates of colorectal cancer (CRC) interval surveyed in screen-detected patients using a fecal immunochemical test (FIT) are not negligible. The aim of this study was to assess the effect of interval cancer on outcomes compared with a population with cancer diagnosed after a positive test result. All patients between 50 and 71 years of age, who were residents of the Mantua district, affected by CRC and operated on from 2005 to 2010 were reviewed. Other than patient-related, disease-related, and treatment-related factors and tumor location, this population was differentiated as either participating or not to screening and then into populations developing interval cancer after a negative FIT result. Mortality was investigated by univariate analysis and by overall survival rates. The mean age of the 975 patients enrolled was 62 years (61.7% males). Most patients (n=575, 59%) were not screen detected, and 400 (41%) were screen detected. Fifty-six (5.7%) patients in the latter group, representing 14% of the participants, developed interval cancer after a negative FIT result. Their cancer was mostly localized in the right colon (41.1%) instead of the left colon and rectum (P=0.02). They also showed higher stages (P=0.001), a moderate degree of differentiation (P=0.001), and overall higher mortality rates than patients with cancer diagnosed after a positive test result (P=0.001). The effect of interval CRC after screening with FIT resulted in worse outcomes compared with the FIT-positive group. With such findings, patients who had negative results for FIT should be informed of the risk of developing cancer within the rounds of screening to independently gain educational skills in the area of health prevention.

Prevalence of polyps ≥6 mm on follow-up CT colonography in a cohort with no significant colon polyps at baseline

AIM

Assess the prevalence of neoplasia ≥6 mm at repeat CT colonoscopy (CTC) in individuals with no significant lesions at baseline.

METHODS

Individuals aged ≥18 years, with/without CRC risk factors, with no polyps ≥6 mm on baseline CTC (negative baseline) who underwent repeat CTC in a large HMO from 2001 to 2011 were retrospectively identified. Studies were reviewed by board-certified radiologists with experience interpreting CTC. Demographic details, CRC risk factors, and the number, size, and location of incident lesions were noted. Findings were classified using the C-RADS scale. Lesion prevalence at CTC-2 was determined, and study interval and risk characteristics of patients with- and without findings were compared.

RESULTS

Our study included 636 individuals (369 men [58.0%]; mean age 59.9 years) with negative baseline CTC who underwent repeat CTC after a mean 4.6 year interval (SD 1.6 years). At baseline, 469/636 (73.7%) were at average risk for CRC; 418 remained at average risk for CTC-2 with 51 (8.0%) developing new risk factors in the interval between studies. At CTC-2, 47 participants (7.4%) presented 52 significant neoplasia: 35 polyps 6-9 mm, 14 polyps ≥10 mm, and 3 masses in 3/636 participants (0.47%). 2/3 masses, 6/14 polyps ≥10 mm (42.9%), and 12/25 polyps 6-9 mm (48.0%) were in individuals with risk factors for CRC. Histopathology was available for 12/52 lesions (23.1%): 8 tubular adenomas, 2 villous adenomas, 1 hamartomatous polyp, 1 case of normal tissue.

CONCLUSION

A mean 4.6 years after negative-baseline CTC, neoplasia ≥6 mm were seen in 7.4% of participants, including masses in 0.47%, supporting recommendations for a 5-year study interval.

Colon cancer screening with CT colonography: logistics, cost-effectiveness, efficiency and progress

Colorectal cancer (CRC) incidence and mortality can be significantly reduced by population screening. Several different screening methods are currently in use, and this review focuses specifically on the imaging technique computed tomographic colonography (CTC). The challenges and logistics of CTC screening, as well as the importance of test accuracy, uptake, quality assurance and cost-effectiveness will be discussed. With comparable advanced adenoma detection rates to colonoscopy (the most commonly used whole-colon investigation), CTC is a less-invasive alternative, requiring less laxative, and with the potential benefit that it permits assessment of extra colonic structures. Three large-scale European trials have contributed valuable evidence supporting the use of CTC in population screening, and highlight the importance of selecting appropriate clinical management pathways based on initial CTC findings. Future research into CTC-screening will likely focus on radiologist training and CTC quality assurance, with identification of evidence-based key performance indicators that are associated with clinically-relevant outcomes such as the incidence of post-test interval cancers (CRC occurring after a presumed negative CTC). In comparison to other CRC screening techniques, CTC offers a safe and accurate option that is particularly useful when colonoscopy is contraindicated. Forthcoming cost-effectiveness analyses which evaluate referral thresholds, the impact of extra-colonic findings and real-world uptake will provide useful information regarding the feasibility of future CTC population screening.

Detection of potentially relevant extracolonic and colorectal findings at CT colonography in a low-risk symptomatic patient population

PURPOSE

CT colonography (CTC) is a widely accepted examination tool for detection of colorectal lesions but evidence of the proportions of relevant extracolonic findings (ECF) in a large symptomatic but still relatively low-risk cohort is lacking, as well as their relationship to symptoms, age, and sex.

METHODS

All patients (n = 3208) with colorectal symptoms, imaged between January 2007 and September 2016 with first-time CTC, were retrospectively selected. The majority (96.7%) was examined with low-dose unenhanced protocol. The most relevant ECF and colorectal lesions (≥6 mm) were prospectively assessed according to C-RADS classifications. Follow-up was elaborated based on the electronic record review. Chi-square test was utilized for evaluating the associations between relevant findings and symptoms, age, and sex.

RESULTS

A total of 270 (8.4%) patients were classified as C-RADS E3, 63 (2.0%) patients as C-RADS E4, and 437 (13.6%) patients were assessed with colorectal lesions (C-RADS C2-4). At follow-up, two thirds of ECF turned out to be a malignancy or relevant disease that required further medical attention. The proportion of ECF was not related to specific colorectal symptoms. Patients aged ≥65 years and men had significantly higher proportions of ECF than younger patients (C-RADS E3 p = 0.005; C-RADS E4 p < 0.001) and women (C-RADS E3 p = 0.013; C-RADS E4 p = 0.009), respectively.

CONCLUSION

Proportions of relevant ECF and colorectal findings are relatively low in symptomatic low-risk patients. By use of CTC as a singular examination, especially in elderly patients, most colonoscopies can be avoided with the benefit of diagnosing relevant ECF without introducing substantial over-diagnosis.

Colorectal cancer screening

Colorectal cancer, which is the leading cancer in Singapore, can be prevented by increased use of screening and polypectomy. A range of screening strategies such as stool-based tests, flexible sigmoidoscopy, colonoscopy and computed tomography colonography are available, each with different strengths and limitations. Primary care physicians should discuss appropriate screening modalities with their patients, tailored to their individual needs. Physicians, patients and the government should work in partnership to improve uptake of colorectal cancer screening to reduce the morbidity and mortality from colorectal cancer.

Increasing Navigation Speed at Endoluminal CT Colonography Reduces Colonic Visualization and Polyp Identification

As navigation speed increases, gaze of the reader becomes more central and polyp identification rates fall.

Purpose

To investigate the effect of increasing navigation speed on the visual search and decision making during polyp identification for computed tomography (CT) colonography

Materials and Methods

Institutional review board permission was obtained to use deidentified CT colonography data for this prospective reader study. After obtaining informed consent from the readers, 12 CT colonography fly-through examinations that depicted eight polyps were presented at four different fixed navigation speeds to 23 radiologists. Speeds ranged from 1 cm/sec to 4.5 cm/sec. Gaze position was tracked by using an infrared eye tracker, and readers indicated that they saw a polyp by clicking a mouse. Patterns of searching and decision making by speed were investigated graphically and by multilevel modeling.

Results

Readers identified polyps correctly in 56 of 77 (72.7%) of viewings at the slowest speed but in only 137 of 225 (60.9%) of viewings at the fastest speed (P = .004). They also identified fewer false-positive features at faster speeds (42 of 115; 36.5%) of videos at slowest speed, 89 of 345 (25.8%) at fastest, P = .02). Gaze location was highly concentrated toward the central quarter of the screen area at faster speeds (mean gaze points at slowest speed vs fastest speed, 86% vs 97%, respectively).

Conclusion

Faster navigation speed at endoluminal CT colonography led to progressive restriction of visual search patterns. Greater speed also reduced both true-positive and false-positive colorectal polyp identification.

^© RSNA, 2017

Online supplemental material is available for this article.

Irritable bowel syndrome evaluation using computed tomography colonography

AIM

To evaluate the morphology of the colon in patients with irritable bowel syndrome (IBS) by using computed tomography colonography (CTC).

METHODS

Twelve patients with diarrhea type IBS (IBS-D), 13 patients with constipation type IBS (IBS-C), 12 patients with functional constipation (FC) and 14 control patients underwent colonoscopy following CTC. The lengths of the rectosigmoid colon, transverse colon and the total colon were measured. The diameters of the rectum, sigmoid colon, descending colon, transverse colon, and ascending colon were measured.

RESULTS

The mean length of the total colon was 156.5 cm in group C, 158.9 cm in group IBS-D, 172.0 cm in group IBS-C, and 188.8 cm in group FC. The total colon in group FC was significantly longer than that in group C (P < 0.05). The mean length of the rectosigmoid colon was 56.2 cm, 55.9 cm, 63.6cm, and 77.4 cm (NS). The mean length of the transverse colon was 49.9 cm, 43.1 cm, 57.0 cm, and 55.0 cm. The transverse colon in group IBS-D was significantly shorter than that in group IBS-C (P < 0.01) and that in group FC (P = 0.02). The mean diameter of the sigmoid colon was 4.0 cm, 3.3 cm, 4.2 cm, and 4.3 cm (NS). The mean diameter of the descending colon was 3.6 cm, 3.1 cm, 3.8 cm, and 4.3 cm. The descending colon diameter in group IBS-D was significantly less than that in group IBS-C (P = 0.03) and that in group FC (P < 0.001). The descending colon diameter in group FC was significantly greater than that in group C (P = 0.04). The mean diameter of the transverse colon was 4.4 cm, 3.3 cm, 4.2 cm, and 5.0 cm (NS).

CONCLUSION

CT colonography might contribute the clarification of subtypes of IBS.

Glucose-6-phosphate dehydrogenase deficiency and risk of colorectal cancer in Northern Sardinia: A retrospective observational study

Glucose-6-phosphate dehydrogenase (G6PD) deficiency has been associated with a lower cancer risk, possibly via a reduction of mutagenic oxygen-free radicals and by reducing nicotinamide-adeninedinucleotide-phosphate for replicating cells. In Sardinia, the enzyme defect is frequent as a consequence of selection by malaria in the past. This study investigated the relationship between G6PD deficiency and colorectal cancer (CRC).A retrospective case-control study of 3901 patients from Sardinia, who underwent a colonoscopy between 2006 and 2016, was performed. G6PD phenotype was assessed for each subject. The proportion of pre and malignant colorectal lesions was compared in cases (G6PD-deficient) and controls (G6PD-normal). Data concerning age, sex, family history of CRC, smoking habits, body height, and weight, and also associated diseases were collected.The CRC risk reduction was 43.2% among G6PD-deficient compared with G6PD-normal subjects (odds ratio 0.57, 95% confidence interval 0.37-0.87, P = 0.010). Age, sex, family history of CRC, and also comorbidities such as type 1 diabetes and ischemic heart disease, were significantly associated with CRC risk. The protective effect of G6PD deficiency remained significant after adjusting for all covariates by logistic regression analysis, and was consistently lower across all age groups.Glucose-6-phosphate dehydrogenase enzyme deficiency is associated with a reduced risk of CRC.

Colorectal cancer development and advances in screening

Most colon tumors develop via a multistep process involving a series of histological, morphological, and genetic changes that accumulate over time. This has allowed for screening and detection of early-stage precancerous polyps before they become cancerous in individuals at average risk for colorectal cancer (CRC), which may lead to substantial decreases in the incidence of CRC. Despite the known benefits of early screening, CRC remains the second leading cause of cancer-related deaths in the United States. Hence, it is important for health care providers to have an understanding of the risk factors for CRC and various stages of disease development in order to recommend appropriate screening strategies. This article provides an overview of the histological/molecular changes that characterize the development of CRC. It describes the available CRC screening methods and their advantages and limitations and highlights the stages of CRC development in which each screening method is most effective.

CT Colonography: an update on current and future indications

Computed tomographic colonography (CTC) is a minimally invasive, patient-friendly, safe and robust colonic imaging modality. The technique is standardized and consolidated evidence from the literature shows that the diagnostic performances for the detection of colorectal cancer and large polyps are similar to colonoscopy (CS) and largely superior to alternative radiological exams, like barium enema. A clear understanding of the exact role of CTC will be beneficial to maximize the benefits and minimize the potential sources of frustration or disappointment for both referring clinicians and patients. Incomplete, failed, or unfeasible CS; investigation of elderly, and frail patients and assessment of diverticular disease are major indications supported by evidence-based data and agreed by the endoscopists. The use of CTC for symptomatic patients, colorectal cancer screening and colonic surveillance is still under debate and, thus, recommended only if CS is unfeasible or refused by patients.

Advanced imaging of colorectal cancer: From anatomy to molecular imaging

Imaging techniques play a key role in the management of patients with colorectal cancer. The introduction of new advanced anatomical, functional, and molecular imaging techniques may improve the assessment of diagnosis, prognosis, planning therapy, and assessment of response to treatment of these patients. Functional and molecular imaging techniques in clinical practice may allow the assessment of tumour-specific characteristics and tumour heterogeneity. This paper will review recent developments in imaging technologies and the evolving roles for these techniques in colorectal cancer.

TEACHING POINTS

• Imaging techniques play a key role in the management of patients with colorectal cancer. • Advanced imaging techniques improve the evaluation of these patients. • Functional and molecular imaging allows assessment of tumour hallmarks and tumour heterogeneity.

Colorectal cancer screening: a global overview of existing programmes

Colorectal cancer (CRC) ranks third among the most commonly diagnosed cancers worldwide, with wide geographical variation in incidence and mortality across the world. Despite proof that screening can decrease CRC incidence and mortality, CRC screening is only offered to a small proportion of the target population worldwide. Throughout the world there are widespread differences in CRC screening implementation status and strategy. Differences can be attributed to geographical variation in CRC incidence, economic resources, healthcare structure and infrastructure to support screening such as the ability to identify the target population at risk and cancer registry availability. This review highlights issues to consider when implementing a CRC screening programme and gives a worldwide overview of CRC burden and the current status of screening programmes, with focus on international differences.

The conundrum of the young colon cancer patient

BACKGROUND

Colonoscopy has had a major impact on the incidence and survival of colon cancer for patients who are screened, usually beginning at the age of 50. Meanwhile, the incidence rate of colon cancer is actually increasing in the patients younger than 50 while no routine screening is implemented for this age group.

METHODS

All patients surgically treated for colon cancer (2004-2011) without preexisting high-risk characteristics (hereditary nonpolyposis colorectal cancer, inflammatory bowel disease) were included (n = 1,015). Age-related disparities in baseline disease and outcomes were reviewed.

RESULTS

Patients younger than 50 years of age (n = 108; 10.6%) had the greatest baseline rates of metastatic (20.4% vs 8.0%; P < .001), node-positive disease (54.6% vs 39.4%; P = .002), and greater rates of extramural vascular invasion (38.9 vs 29.4%; P = .043). Cancer-related mortality also was greatest in this group (28.7 vs 18.4%; P = .011). Multivariable Cox regression shows that patients younger than 50 are still at significantly greater risk of mortality after adjustment for effects of age, baseline AJCC staging, smoking, and comorbidity (hazard ratio: 1.57, 95% confidence interval 1.01-2.45; P = .049).

DISCUSSION

Patients younger than 50 present with the most advanced and aggressive disease, giving them the worst stage-independent prognosis of all age groups. Potential causes include age-related differences in tumor biology and underdetection by current screening efforts. This raises the question of how to address the conundrum of the young colon cancer patient, who often is the proverbial needle in a haystack of young patients, with nonspecific gastrointestinal symptoms but who would benefit considerably from early detection.

Colorectal Cancer Screening

Colorectal cancer (CRC) is a leading cause of cancer morbidity and mortality in the Western world. Advances in surgical and medical management have led to improved outcomes; however, the prognosis of CRC is often poor when detected at a symptomatic stage. Most cases of CRC develop over years from removable well-defined precursor lesions, and asymptomatic, curable disease may be detected by convenient noninvasive tests. These features make CRC a suitable candidate for screening, and several options are available. This article outlines the evidence for established CRC screening tests along with a discussion on newer tests and ongoing research.

National Guidelines for Colorectal Cancer Screening in Saudi Arabia with strength of recommendations and quality of evidence

BACKGROUND

Colorectal cancer is the most common cancer among Saudi men and the third commonest among Saudi women. Given the predominance of colorectal cancer compared with other cancers in Saudi Arabia, context-specific guidelines are needed for screening.

METHODS

Experts from the Saudi Society of Colon and Rectal Surgery, Saudi Gastroenterology Association, Saudi Oncology Society, Saudi Chapter of Enterostomal Therapy, Family Medicine and Department of Public Health at the Saudi Arabian Ministry of Health and a patient advocate was assembled by the Saudi Centre for Evidence-Based Healthcare, a subsidiary of the Saudi Arabian Ministry of Health. The panel collaborated with a methodological team from McMaster University, Canada to develop national guidelines for colorectal cancer screening. After identifying key questions, the panel conducted a systematic review of all reports on the utility of screening, the cost of screening for colorectal cancer in Saudi Arabia and on the values and preferences of Saudi patients. Meta- analyses, when appropriate, were performed to generate pooled estimates of effect. Using the GRADE approach, the panel used the evidence-to-decision (EtD) framework to assess all domains important in determining the strength and direction of the recommendations (benefits and harms, values and preferences, resource implications, equity, acceptability, and feasibility). Judgments related to the EtD domains were resolved through consensus or voting, if consensus was not reached. The final recommendations were developed during a two-day meeting held in Riyadh, Saudi Arabia in March 2015. Conflicts of interests among the panel members were handled according to the World Health Organization rules.

LIMITATIONS

There is lack of national data on the incidence of adenomatous polyps or the age groups in which the incidence surges. There were no national clinical trials assessing the effectiveness of the different modalities of screening for colorectal cancer and their impact on mortality.

CONCLUSION

The panel recommends screening for colorectal cancer in Saudi Arabia in asymptomatic Saudi patients at average risk of colorectal cancer. An infrastructure should be built to achieve that goal.