Understanding differences in the guidelines for colorectal cancer screening

Absence of TERT promoter mutations in colorectal precursor lesions and cancer

Hotspot mutations (c.-124bp G > A and c.-146bp G > A) in the promoter region of the TERT gene have been recently described in several types of solid tumors, including glioma, bladder, thyroid, liver and skin neoplasms. However, knowledge with respect to colorectal precursor lesions and cancer is scarce. In the present study we aimed to determine the frequency of hotspot TERT promoter mutations in 145 Brazilian patients, including 103 subjects with precursor lesions and 42 with colorectal carcinomas, and we associated the presence of such mutations with the patients clinical-pathological features. The mutation analysis was conclusive in 123 cases, and none of the precursor and colorectal carcinoma cases showed TERT promoter mutations. We conclude that TERT mutations are not a driving factor in colorectal carcinogenesis.

KRAS and BRAF somatic mutations in colonic polyps and the risk of metachronous neoplasia

Background & aims

High-risk features of colonic polyps are based on size, number, and pathologic characteristics. Surveillance colonoscopy is often recommended according to these findings. This study aimed to determine whether the molecular characteristics of polyps might provide information about the risk of metachronous advanced neoplasia.

Methodology

We retrospectively included 308 patients with colonic polyps. A total of 995 polyps were collected and tested for somatic BRAF and KRAS mutations. Patients were classified into 3 subgroups, based on the polyp mutational profile at baseline, as follows: non-mutated polyps (Wild-type), at least one BRAF-mutated polyp, or at least one KRAS-mutated polyp. At surveillance, advanced adenomas were defined as adenomas ≥ 10 mm and/or with high grade dysplasia or a villous component. In contrast, advanced serrated polyps were defined as serrated polyps ≥ 10 mm in any location, located proximal to the splenic flexure with any size or with dysplasia.

Results

At baseline, 289 patients could be classified as wild-type (62.3%), BRAF mutated (14.9%), or KRAS mutated (22.8%). In the univariate analysis, KRAS mutations were associated with the development of metachronous advanced polyps (OR: 2.36, 95% CI: 1.22–4.58; P = 0.011), and specifically, advanced adenomas (OR: 2.42, 95% CI: 1.13–5.21; P = 0.023). The multivariate analysis, adjusted for age and sex, also showed associations with the development of metachronous advanced polyps (OR: 2.27, 95% CI: 1.15–4.46) and advanced adenomas (OR: 2.23, 95% CI: 1.02–4.85).

Conclusions

Our results suggested that somatic KRAS mutations in polyps represent a potential molecular marker for the risk of developing advanced neoplasia.

Ethical issues with colorectal cancer screening-a systematic review

RATIONALE, AIMS, AND OBJECTIVES

Colorectal cancer (CRC) screening is widely recommended and implemented. However, sometimes CRC screening is not implemented despite good evidence, and some types of CRC screening are implemented despite lack of evidence. The objective of this article is to expose and elucidate relevant ethical issues in the literature on CRC screening that are important for open and transparent deliberation on CRC screening.

METHODS

An axiological question-based method is used for exposing and elucidating ethical issues relevant in HTA. A literature search in MEDLINE, Embase, PsycINFO, PubMed Bioethics subset, ISI Web of Knowledge, Bioethics Literature Database (BELIT), Ethics in Medicine (ETHMED), SIBIL Base dati di bioetica, LEWI Bibliographic Database on Ethics in the Sciences and Humanities, and EUROETHICS identified 870 references of which 114 were found relevant according to title and abstract. The content of the included papers were subject to ethical analysis to highlight the ethical issues, concerns, and arguments.

RESULTS

A wide range of important ethical issues were identified. The main benefits are reduced relative CRC mortality rate, and potentially incidence rate, but there is no evidence of reduced absolute mortality rate. Potential harms are bleeding, perforation, false test results, overdetection, overdiagnosis, overtreatment (including unnecessary removal of polyps), and (rarely) death. Other important issues are related to autonomy and informed choice equity, justice, medicalization, and expanding disease.

CONCLUSION

A series of important ethical issues have been identified and need to be addressed in open and transparent deliberation on CRC screening.

KRAS and BRAF mutations and MSI status in precursor lesions of colorectal cancer detected by colonoscopy

Colorectal cancer (CRC) is one of the most frequent cancers worldwide. Adenoma is the main precursor lesion and, recently, the serrated polyps were described as a group of colorectal lesions with malignant potential. The morphologic and biologic characterizations of serrated polyps remain limited. The aim of the present study was to determine the frequency of KRAS and BRAF mutations and microsatellite instability (MSI) in CRC precursor lesions, to evaluate the association between molecular, pathologic and morphologic alterations in precursor lesions and to compare with the alterations detected in CRC. A series of 342 precursor lesions were removed from 155 patients during colonoscopy. After morphologic classification, molecular analysis was performed in 103 precursor lesions, and their genetic profile compared with 47 sporadic CRCs. Adenomas were the main precursor lesions (70.2%). Among the serrated polyps, the main precursor lesion was hyperplastic polyps (HPs) (82.4%), followed by sessile serrated adenomas (12.7%) and traditional serrated adenomas (2.0%). KRAS mutations were detected in 13.6% of the precursor lesions, namely in adenomas and in HPs, but in no serrated adenoma. BRAF mutations were found in 9 (8.7%) precursor lesions, mainly associated with serrated polyps and absent in adenomas (P<0.001). High MSI (MSI-H) was absent in precursor lesions. In the 47 CCR cases, 46.8% exhibited KRAS mutation, 6.5% BRAF mutations and 10.6% MSI-H. This study confirms the role of KRAS and BRAF mutations in CRC carcinogenesis, a crucial step in implementing CRC screening strategies.

Cervical cancer screening in the United States and the Netherlands: a tale of two countries

CONTEXT

This article compares cervical cancer screening intensity and cervical cancer mortality trends in the United States and the Netherlands to illustrate the potential of cross-national comparative studies. We discuss the lessons that can be learned from the comparison as well as the challenges in each country to effective and efficient screening.

METHODS

We used nationally representative data sources in the United States and the Netherlands to estimate the number of Pap smears and the cervical cancer mortality rate since 1950. The following questions are addressed: How do differences in intensity of Pap smear use between the countries translate into differences in mortality trends? Can population coverage rates (the proportion of eligible women who had a Pap smear within a specified period) explain the mortality trends better than the total intensity of Pap smear use?

FINDINGS

Even though three to four times more Pap smears per woman were conducted in the United States than in the Netherlands over a period of three decades, the two countries' mortality trends were quite similar. The five-year coverage rates for women aged thirty to sixty-four were quite comparable at 80 to 90 percent. Because screening in the Netherlands was limited to ages thirty to sixty, screening rates for women under thirty and over sixty were much higher in the United States. These differences had consequences for age-specific mortality trends. The relatively good coverage rate in the Netherlands can be traced back to a nationwide invitation system based on municipal population registries. While both countries followed a "policy cycle" involving evidence review, surveillance of screening practices and outcomes, clinical guidelines, and reimbursement policies, the components of this cycle were more systematically linked and implemented nationwide in the Netherlands than in the United States. To a large extent, this was facilitated by a public health model of screening in the Netherlands, rather than a medical services model.

CONCLUSIONS

Cross-country studies like ours are natural experiments that can produce insights not easily obtained from other types of study. The cervical cancer screening system in the Netherlands seems to have been as effective as the U.S. system but used much less screening. Adequate coverage of the female population at risk seems to be of central importance.

Colorectal cancer screening and prevention in women

Colorectal cancer (CRC) is the third most common cause of cancer in women. Screening for CRC increases early detection of cancer and premalignant polyps and decreases morbidity from this disease. However, adherence to the screening guidelines continues to remain inadequate both at the physician and patient levels. Several factors are of special importance to women. Presence of prior gynecological malignancies may increase the risk of CRC in women. Furthermore, new studies have shown other factors such as obesity and smoking to increase the risk of CRC in women. This article highlights issues unique to women with regards to CRC and outlines special considerations for determining screening intervals in women, identifies factors that make screening more difficult in women, and reviews studies that identify preventative strategies which, together with screening, may reduce the burden of CRC.

Are colorectal cancer screening recommendations for first-degree relatives of patients with adenomas too aggressive?

Consensus guidelines of the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology recommend first-degree relatives of individuals diagnosed with an adenoma before age 60 should be screened every 5 years with colonoscopy starting at age 40. This is the identical recommendation for those with a first-degree relative diagnosed with colorectal cancer (CRC) before age 60. There is good evidence that first-degree relatives of individuals diagnosed with CRC before age 60 are at substantially increased risk for developing cancer at a young age. However, it is unclear whether an individual with a first-degree relative with an adenoma diagnosed before age 60 is at increased risk of CRC. Because not all adenomas portend the same cancer risk in the individual who has the adenoma, they would not be expected to portend the same risk in their first-degree relatives. Because of these uncertainties, the US Preventive Services Task Force does not recommend more aggressive screening of first-degree relatives of individuals with an adenoma. The adenoma detection rate for individuals 50 to 59 years old without a first-degree relative with CRC is sufficiently high (approximately 25%-30%) that almost half the population would be high risk on the basis of one first-degree relative having an adenoma. Given the weakness of evidence supporting the guidelines, suboptimal levels of screening in the general population, and lack of resources to comply with the recommendation, first-degree relatives of individuals with adenomas should be screened as average-risk persons until more compelling data are available to justify more aggressive screening.

Guidelines for colorectal cancer screening--a puzzle of tests and strategies

Colorectal cancer (CRC) is a leading cause of cancer death around the World. An effective way to reduce colorectal cancer mortality is to screen for it and its precursor, the adenoma. In industrialized countries the mortality related to CRC is decreasing probably due to better screening programmes in average-risk individuals as well as changes in risk factors. Screening procedures are various including faecal screening tests--which primarily detect colon cancer--and structural tests (endoscopy--flexible sigmoidoscopy or colonoscopy--, Barium enema, Computed Tomography Colonography) that may detect not only cancer but also its precursors. Video-colon capsule is a new tool for exploring the colon but needs further studies before becoming a screening test. The choice of a screening test includes several factors as cost, invasiveness, acceptability, adherence to repeat testing and acceptance referral for colonoscopy for positive tests as well as local financial resources. Every screening programme has advantages and limitations. Enhancing use and quality of CRC screening programmes is mandatory.

Colorectal cancer screening

PURPOSE OF REVIEW

The review will summarize the state of the art in colon cancer screening. Recently published screening guidelines will be reviewed so physicians can understand them and how to deal with the differences. Each screening modality presently in use will then be reviewed with emphasis on efficacy and problems.

RECENT FINDINGS

During the past two decades research has clearly demonstrated colon cancer screening to be effective. New modalities such as virtual colonoscopy and stool DNA screening have been introduced and are recommended by some organizations but not others. Ages to discontinue screening have also been suggested. Fecal immunochemical testing exhibits some advantages over guaiac-based testing. Problematic issues with the effectiveness of colonoscopy have arisen, particularly in the proximal colon. Both technical and biological reasons have been suggested for this decrease in effectiveness.

SUMMARY

Colon cancer screening is effective and continues to improve. Refinements of guidelines as well as refinements in each screening modality have occurred. Several screening tools are newly available and quality studies and efforts for present and new tests are imperative.