Colorectal Cancer Risk in Patients With Lynch Syndrome and Inflammatory Bowel Disease

Rare single-nucleotide variants of MLH1 and MSH2 genes in patients with Lynch syndrome

BACKGROUND

Approximately 5% of colorectal cancers (CRCs) are hereditary. Lynch syndrome (LS), also known as hereditary nonpolyposis colorectal cancer (HNPCC), is the most common form of recognized hereditary CRC. Although Iran, as a developing country, has a high incidence of CRC, the spectrum of variants has yet to be thoroughly investigated.

AIMS

This study aimed to investigate pathogenic and non-pathogenic variants in MLH1 and MSH2 genes in Iranian patients with suspected Lynch syndrome (sLS).

METHODS AND RESULTS

In the present study, 25 peripheral blood samples were collected from patients with sLS and high microsatellite instability (MSI-H). After DNA extraction, all samples underwent polymerase chain reaction and Sanger sequencing to identify the variants in the exons of MLH1 and MSH2 genes. The identified variants were interpreted using prediction tools, and were finally reported under ACMG guidelines. In our study population, 13 variants were found in the MLH1 gene and 8 in the MSH2 gene. Interestingly, 7 of the 13 MLH1 variants and 3 of the 8 MSH2 variants were novel, whereas the remaining variants were previously reported or available in databases. In addition, some patients with sLS did not have variants in the exons of the MLH1 and MSH2 genes. The variants detected in the MLH1 and MSH2 genes had specific characteristics regarding the number, area of occurrence, and their relationship with demographic and clinicopathologic features.

CONCLUSION

Overall, our results suggest that analysis of MLH1 and MSH2 genes alone is insufficient in the Iranian population, and more comprehensive tests are recommended for detecting LS.

Inflammatory bowel disease and bladder cancer risk: based on a Mendelian randomization study

BACKGROUND

Prior epidemiological observational studies have duly documented a correlative link between inflammatory bowel disease (IBD) and bladder cancer (BC); however, the establishment of a definitive causal relationship has remained elusive. The principal objective of this meticulous investigation was to rigorously evaluate the causal nexus between IBD and BC, employing the robust methodology of Mendelian randomization (MR) analysis.

METHODS

We meticulously performed both univariate and multivariate Mendelian randomization (MVMR) analyses employing publicly accessible genome-wide association study (GWAS) data. The central approach employed for our investigations was inverse variance weighting (IVW) method, while diligently scrutinizing potential sources of heterogeneity and horizontal pleiotropy via the rigorous utilization of Cochran's Q test, the MR-PRESSO method, and MR-Egger.

RESULTS

In the univariate MR analysis, no causal link was observed between genetic prediction of IBD and BC. Furthermore, both Crohn's disease (CD) and ulcerative colitis (UC) showed no causal association with BC. The consistent association between CD and UC in the MVMR analysis supports this finding.

CONCLUSION

This study found no genetic basis for the causative association of IBD and BC. It is crucial to emphasize that further comprehensive investigations are warranted to delve into the intricate underlying mechanisms that may contribute to these associations.

Inflammatory bowel disease and prostate cancer risk: a two-sample Mendelian randomization analysis

Background

Previous epidemiological observational studies have reported an association between inflammatory bowel disease (IBD) and prostate cancer (PCa), but the causality is inconclusive. The purpose of this study was to evaluate the causality of IBD on PCa using the mendelian randomization (MR) analysis.

Methods

We performed a two-sample MR analysis with public genome-wide association studies (GWAS) data. Eligible instrumental variables (IVs) were selected according to the three assumptions of MR analysis. The inverse-variance weighted (IVW) method was the main method. Complementary methods included the MR-Egger regression, the Weighted Median, the Simple Mode, the Weighted Mode and MR pleiotropy residual sum and outlier (MR-PRESSO) methods.

Results

Genetically determined IBD did not have a causal effect on PCa (IVW P > 0.05). Additionally, there was no causal effect of Crohn's disease (CD) and ulcerative colitis (UC) on PCa in the MR analysis (IVW P > 0.05). Results of complementary methods were consistent with those of the IVW method.

Conclusions

This study does not support a causal association of IBD on PCa, which is in contrast to most observational studies.

Alterations in p53, Microsatellite Stability and Lack of MUC5AC Expression as Molecular Features of Colorectal Carcinoma Associated with Inflammatory Bowel Disease

Colitis-associated colorectal carcinoma (CAC) occurs in inflammatory bowel disease (IBD) because of the "chronic inflammation-dysplasia-cancer" carcinogenesis pathway characterized by p53 alterations in the early stages. Recently, gastric metaplasia (GM) has been described as the initial event of the serrated colorectal cancer (CRC) process, resulting from chronic stress on the colon mucosa. The aim of the study is to characterize CAC analyzing p53 alterations and microsatellite instability (MSI) to explore their relationship with GM using a series of CRC and the adjacent intestinal mucosa. Immunohistochemistry was performed to assess p53 alterations, MSI and MUC5AC expression as a surrogate for GM. The p53 mut-pattern was found in more than half of the CAC, most frequently stable (MSS) and MUC5AC negative. Only six tumors were unstable (MSI-H), being with p53 wt-pattern (p = 0.010) and MUC5AC positive (p = 0.005). MUC5AC staining was more frequently observed in intestinal mucosa, inflamed or with chronic changes, than in CAC, especially in those with p53 wt-pattern and MSS. Based on our results, we conclude that, as in the serrated pathway of CRC, in IBD GM occurs in inflamed mucosa, persists in those with chronic changes and disappears with the acquisition of p53 mutations.

Case Report: Multiple colorectal cancers in a patient with Ulcerative colitis and Lynch syndrome: Is there a role for prophylactic colectomy? A short report and review of literature

It is a known fact that Lynch syndrome (LS) and Ulcerative colitis (UC) are individually associated with increased risk of colorectal cancer. While there is no conclusive evidence to demonstrate a cumulative risk when these two conditions coexist, available data suggest early onset and synchronous cancers are synonymous to this group. We have reported an unusual case of multiple synchronous colorectal cancers in a young man with ulcerative colitis and Lynch syndrome also known as Hereditary Nonpolyposis Colorectal Cancer (HNPCC) gene mutation. We propose that conducting a detailed genetic mutation profile in LS patients may play a key role in guiding the intensity of endoscopic surveillance and that a concerted, pragmatic, patient guided approach should be adopted on the subject of prophylactic colectomy when UC and LS co-exist.

Hereditary Colorectal Cancer Syndromes and Inflammatory Bowel Diseases: an ECCO CONFER Multicentre Case Series

BACKGROUND

Hereditary colorectal cancer syndromes [HCCS] are rare polyposis or nonpolyposis syndromes with a higher risk of developing colorectal cancer [CRC]. Coexisting inflammatory bowel disease [IBD], including ulcerative colitis [UC] and Crohn's disease [CD], with HCCS is exceedingly rare and presumably increases the risk of early-onset CRC.

METHODS

This was a multicentre case series performed as a part of the European Crohn's and Colitis Organisation [ECCO] Collaborative Network of Exceptionally Rare case reports [CONFER] project.

RESULTS

This report includes 26 patients with IBD (10 UC, 15 CD, and one with IBD unclassified [IBD-U]) and concomitant HCCS. Among these 26 patients([median age 33 years, interquartile range [IQR] 20-44], 15 [57.7%] were males, 24 [92.3%] Caucasians, and two [7.7%] of Arab origin. HCCS was diagnosed before the IBD diagnosis in 11 patients [42.3%], after diagnosis of IBD in 11 patients [42.3%], and concurrently in four patients [15.4%]. Sixteen patients had Lynch syndrome, seven had familial adenomatous polyposis [FAP], two had MYH-associated polyposis [MAP], and one had attenuated FAP [AFAP]. The most frequent genetic mutations were those of APC [n = 7] and MLH1 [n = 7]. Overall, CRC developed in 38.5% of patients [n = 10]: in four patients [40%] after IBD diagnosis, in four [40%] patients before IBD diagnosis, and in two patients the two conditions were diagnosed simultaneously. Eighteen [69.2%] patients underwent colectomy or abdominal surgery: nine patients due to CRC diagnosis, five patients preventively due to the underlying HCCS, three due to the underlying HCCS and concomitant active IBD disease, and one patient because of active IBD disease. One patient died due to CRC.

CONCLUSIONS

To date, this is the largest case series of patients with IBD and HCCS. The most frequent diagnosis of HCCS associated with IBD was Lynch syndrome. These data demonstrate the high malignancy rate and surgical intervention rate in this IBD cohort, despite the endoscopic surveillance. The optimal medical approach still needs to be addressed.

Loss of mismatch repair promotes a direct selective advantage in human stem cells

Lynch syndrome (LS) is the most common hereditary form of colon cancer, resulting from a germline mutation in a DNA mismatch repair (MMR) gene. Loss of MMR in cells establishes a mutator phenotype, which may underlie its link to cancer. Acquired downstream mutations that provide the cell a selective advantage would contribute to tumorigenesis. It is unclear, however, whether loss of MMR has other consequences that would directly result in a selective advantage. We found that knockout of the MMR gene MSH2 results in an immediate survival advantage in human stem cells grown under standard cell culture conditions. This advantage results, in part, from an MMR-dependent response to oxidative stress. We also found that loss of MMR gives rise to enhanced formation and growth of human colonic organoids. These results suggest that loss of MMR may affect cells in ways beyond just increasing mutation frequency that could influence tumorigenesis.

Recombinant Bifidobacterium longum Carrying Endostatin Protein Alleviates Dextran Sodium Sulfate-Induced Colitis and Colon Cancer in Rats

Bifidobacterium has been widely administrated orally as probiotics to prevent pathogen colonization and modulate the gut microbiome balance. Endostatin is an endogenous inhibitor of angiogenesis and has been shown to inhibit tumor growth, invasion, and metastasis. At present, the combination of endostatin and chemotherapeutic drugs has been regarded as a promising antitumor treatment strategy. In this study, we selected a safe strain of Bifidobacterium longum as a delivery system to transport endostatin to the gastrointestinal tract and explored their combined effect on inflammatory bowel disease (IBD) and colitis-associated cancer. The results indicated that B. longum-Endo relieved dextran sulfate sodium-induced body weight loss, diarrhea, colon shortening, and epithelium damage. Long-term oral administration of B. longum-Endo significantly decreased tumor formation rate, tumor number, and tumor size. Moreover, the effect of B. longum-Endo on gut microbiota dysbiosis was also confirmed by 16S rRNA sequencing analysis. The levels of potentially beneficial bacteria, such as Lactobacillus, Bifidobacterium, Allobaculum, and Parabateroides, were increased in the B. longum-Endo group compared to the model and B. longum groups. Meanwhile, levels of potentially pathogenic bacteria including Desulfovibrio, Helicobacter, and Enterorhabdus were decreased. Taken together, these results suggested that oral administration of recombinant B. longum-Endo strain may be a promising therapeutic strategy for IBD and colitis-associated cancer.

Endoscopic colorectal cancer surveillance in inflammatory bowel disease: Considerations that we must not forget

Inflammatory bowel disease (IBD), encompassing Crohn's disease and ulcerative colitis, is a chronic immune-mediated inflammatory disease that primarily affects the gastrointestinal tract and is characterized by periods of activity and remission. The inflammatory activity of the disease involving the colon and rectum increases the risk of colorectal cancer (CRC) over the years. Although prevention strategies are evolving, regular surveillance for early detection of neoplasia as a secondary prevention strategy is paramount in the care of IBD patients. In this review article, we discuss the current evidence of the risks of developing CRC and evaluate the best available strategies for screening and surveillance, as well as future opportunities for cancer prevention.

Association of cancer with comorbid inflammatory conditions and treatment in patients with Lynch syndrome

BACKGROUND

Individuals with Lynch syndrome (LS) and hereditary non-polyposis colorectal cancer (HNPCC) are at increased risk of both colorectal cancer and other cancers. The interplay between immunosuppression, a comorbid inflammatory condition (CID), and HNPCC on cancer risk is unclear.

AIM

To evaluate the impact of CIDs, and exposure to monoclonal antibodies and immunomodulators, on cancer risk in individuals with HNPCC.

METHODS

Individuals prospectively followed in a hereditary cancer registry with LS/HNPCC with the diagnosis of inflammatory bowel disease or rheumatic disease were identified. We compared the proportion of patients with cancer in LS/HNPCC group with and without a CID. We also compared the proportion of patients who developed cancer following a CID diagnosis based upon exposure to immunosuppressive medications.

RESULTS

A total of 21 patients with LS/HNPCC and a CID were compared to 43 patients with LS/HNPCC but no CID. Cancer occurred in 84.2% with a CID compared to 76.7% without a CID (P = 0.74) with no difference in age at first cancer diagnosis 45.5 ± 14.6 vs 43.8 ± 7.1 years (P = 0.67). LS specific cancers were diagnosed in 52.4% with a CID vs 44.2% without a CID (P = 0.54). Nine of 21 (42.9%) patients were exposed to biologics or immunomodulators for the treatment of their CID. Cancer after diagnosis of CID was seen in 7 (77.8%) of exposed individuals vs 5 (41.7%) individuals unexposed to biologics/immunomodulators (P = 0.18). All 7 exposed compared to 3/5 unexposed developed a LS specific cancer. The exposed and unexposed groups were followed for a median 10 years and 8.5 years, respectively. The hazard ratio for cancer with medication exposure was 1.59 (P = 0.43, 95%CI: 0.5-5.1).

CONCLUSION

In patients with LS/HNPCC, the presence of a concurrent inflammatory condition, or use of immunosuppressive medication to treat the inflammatory condition, might not increase the rate of cancer occurrence in this limited study.

Colorectal cancer in adolescents and young adults with Lynch syndrome: a Danish register-based study

OBJECTIVE

To assess clinicopathological predictors and prognosis in early-onset colorectal cancer (CRC) in Lynch syndrome with comparison to patients diagnosed from age 40 and up.

DESIGN

National, retrospective register-based case-control study.

SETTING

Danish national hereditary CRC register.

PARTICIPANTS

Individuals with Lynch syndrome diagnosed with CRC from January 1950 to June 2020. The analysis was based on 215 early-onset CRCs diagnosed between 15 and 39 years of age and 574 CRCs diagnosed at age 40-88 years.

MAIN OUTCOME MEASURES

Clinical and histopathological characteristics and survival. Confounding variables were analysed by Cox analysis.

RESULTS

27.2% of the tumours in the Danish Lynch syndrome cohort were diagnosed under age 40. Disease-predisposing alterations in MLH1 and MSH2 were overrepresented in the age 15-39 cohort compared with patients diagnosed over age 40. CRCs diagnosed under age 40 showed an adverse stage distribution with 36.2% stage III-IV tumours compared with 25.8% in the over age 40 group. However, young patients diagnosed with early-stage tumours did have a significantly better prognosis compared with early-stage tumours in the older age group.

CONCLUSIONS

Early-onset CRC in Lynch syndrome is primarily linked to alterations in MLH1 and MSH2 and displays an adverse stage distribution. These observations serve as a reminder of surveillance, symptom awareness and rapid diagnostic handling of CRC in young adults with Lynch syndrome.

High Variability in Cellular Proliferation, Gene Expression, and Cytokine Production in the Nonneoplastic Colonic Epithelium of Young Apc+/Min-FCCC Mice

An urgent need exists to identify efficacious therapeutic preventive interventions for individuals who are at high risk of developing colorectal cancer. To maximize the benefits of preventive intervention, it is vital to identify the time interval during which the initiation of a preventive intervention will lead to an optimal outcome. The goal of the present study was to determine if oncogenic events can be detected in the nonneoplastic colonic mucosa of Apc+/Min-FCCC mice prior to formation of the first adenoma, thus defining an earlier point of intervention along the cancer continuum. Tissues taken at three potential points of intervention were characterized: prior to Apc mutation (wild type Apc+/+-FCCC mice); after initiation but prior to colon adenoma formation (tumor-free Apc+/Min-FCCC mice); and after formation of the first colon adenoma (tumor-bearing Apc+/Min-FCCC mice). Experimentation focused on molecular processes that are dysregulated in early colon lesions: 1) cellular proliferation (proliferative index and size of the proliferative zone); 2) cellular stemness (expression of Ascl2, Grem1, Lgr5 and Muc2); 3) EGFR signaling (expression of Ereg); and 4) inflammation (expression of Mmp9, Ptsg2, and Reg4, as well as secretion of 18 cytokines involved in immune activation and response). Interestingly, the nonneoplastic colonic mucosa of wild type, tumor-free Apc+/Min-FCCC , and tumor-bearing Apc+/Min-FCCC mice did not display significant differences in average epithelial cell proliferation (fold change 0.8-1.3, p≥0.11), mucosal gene expression (fold change 0.8-1.4, p≥0.22), or secretion of specific cytokines from colonic mucosa (fold change 0.2-1.5, p≥0.06). However, the level of cytokine secretion was highly variable, with many (22% of wild type, 31% of tumor-free Apc+/Min-FCCC , and 31% of tumor-bearing Apc+/Min-FCCC ) mice categorized as outliers (> 1.5 x interquartile ranges below the first quartile or above the third quartile) due to elevated expression of at least one cytokine. In summary, no differences were observed in proliferation, stemness, and EGFR signaling in the colonic mucosa of wild type vs Apc+/Min-FCCC mice, with low baseline cytokine expression, prior to the formation of the first colon adenoma. The results of this study provide valuable baseline data to inform the design of future cancer prevention studies.

Bioactive Components of Polyphenol-Rich and Non-Polyphenol-Rich Cranberry Fruit Extracts and Their Chemopreventive Effects on Colitis-Associated Colon Cancer

Cranberries contain various constituents relevant to human health. Our previous study demonstrated the chemopreventive effects of whole cranberry against colon cancer in mice. In order to determine the role of different cranberry secondary metabolites in inhibiting colon cancer, cranberry ethyl acetate extract (EAE) and polyphenol extract (PPE) were obtained. The free-radical scavenging activities and chemical composition of the cranberry extracts were determined. EAE consisted of triterpenes and sterols and a trace amount of proanthocyanidins. PPE mainly contained polyphenol with a trace amount of triterpenes. The chemopreventive effects of orally administered EAE and PPE on colitis-associated colon carcinogenesis were determined in mice. Dietary EAE and PPE significantly suppressed tumor metrics without noticeable adverse effects. Gene expression levels of key proinflammatory cytokines were also attenuated by EAE and PPE in the mouse colon. In conclusion, the novel cranberry extracts may offer an efficacious and safe means to prevent colonic tumorigenesis in humans.

Incidence of Prostate Cancer in Inflammatory Bowel Disease: A Meta-Analysis

Background and objectives: Inflammatory bowel disease (IBD) is associated with an increased risk of developing colorectal cancer as well as some extra-intestinal tumors, but there are still limited data about the risk of prostate cancer (PC). To analyze if there is an increased risk of PC in patients affected by IBD, we performed a systematic review with meta-analysis. Materials and Methods: A Pubmed search of all studies comparing standardized incidence ratio (SIR) or odds ratio (OR) or relative risks (RR) of PC between IBD and non IBD groups, published until March 2020 was conducted. The study protocol was registered on PROSPERO. Twelve studies, mostly population studies, were included. The quality score of these studies, evaluated by the Newcastle-Ottawa Scale, was 7. The heterogeneity was high among the studies in which ulcerative colitis (UC) was considered separate from Crohn's disease (CD) and in the studies that considered UC and CD together ("IBD-studies"), while it was low in the studies which considered CD separate from UC. Results: The relative risk of developing PC was 1.71 (95% confidence interval [CI] 1.16-2.51, p = 0.007) in IBD, 1.10 (95%CI 0.98-1.25, p = 0.116) in CD, and 1.22 (95%CI 0.98-1.51, p = 0.07) in UC. Conclusions: Patients with IBD appear to have a slightly increased risk of PC compared to the general population.

The association between inflammatory bowel disease and prostate cancer risk: a meta-analysis

BACKGROUND

Patients with inflammatory bowel disease (IBD) are at increased risk of gastrointestinal and extraintestinal malignancies. However, the associations between IBD and prostate cancer (PCa) risk remain conflicting.

METHODS

We conducted a systematic literature search in PubMed, EMBASE, and Web of Science databases. According to the inclusion and exclusion criteria, a total of nine studies were included in the meta-analysis. The pooled standardized incidence ratios (SIRs) or relative risks (RRs) and corresponding 95% confidence intervals (CIs) were calculated to determine the relationship of IBD and PCa risk.

RESULTS

For cohort studies, the pooled SIR was 1.33 (95% CI = 1.03-1.71). The further subgroup analysis showed that the PCa risk was higher in patients with ulcerative colitis (UC) (pooled SIR = 1.58, 95% CI = 1.08-2.30), but not in patients with Crohn's disease (CD) (pooled SIR = 1.12, 95% CI = 0.97-1.31). Besides, for the three case-control studies, the results indicated that compared with normal group, the pooled RR of PCa was 1.81 for the patients with IBD (95% CI = 1.43-2.29). In addition, sensitivity analysis indicated that the results were robust and no significant publication bias were observed.

CONCLUSIONS

Our findings based on the large and multicenter samples strongly indicated that men with IBD especial UC have significantly elevated PCa risk. Future efforts are needed to define the mechanism underlying the link between IBD and PCa or clinically significant PCa risk.

Targeted mutational analysis of inflammatory bowel disease-associated colorectal cancers

Inflammatory bowel disease-associated colorectal carcinomas (IBD-CRCs) develop in a background of chronic inflammation, and thus, the molecular landscape of these tumors likely differs from that of sporadic colorectal cancer. To add to emerging data on molecular alterations present in these tumors, we analyzed our institution's cohort of IBD-CRCs. CRCs resected from patients with IBD underwent molecular analysis via a 50-gene hot-spot solid tumor panel (OncoScreen ST2.0). In-house sporadic CRCs and The Cancer Genome Atlas project data were used for comparison. Fifty-five IBD-CRCs from 48 patients were successfully analyzed. Mutations in TP53 were most common and were present in 69% of IBD-CRCs; a similar percentage of TP53 mutations was detected in sporadic colorectal carcinomas (70%). APC and KRAS mutations were significantly less common in IBD-CRCs than in sporadic CRCs (15% versus 53%, P < .001 and 20% versus 38%, P = .02, respectively). Additionally, the potentially targetable IDH1 R132 mutation was present in 7% of IBD-CRCs but only 1% of sporadic CRCs and The Cancer Genome Atlas CRCs; alterations in other genes with potential targeted therapies were very rare. In conclusion, IBD-CRCs exhibit molecular differences when compared to sporadic CRCs, suggesting different pathways of carcinogenesis, although certain alterations are common to both types of tumors. IDH1 mutations are present in a subset of IBD-CRCs, which may expand therapeutic options in the future.

Hereditary Nonpolyposis Colorectal Cancer and Cancer Syndromes: Recent Basic and Clinical Discoveries

Approximately one-third of individuals diagnosed with colorectal cancer have a family history of cancer, suggesting that CRCs may result from a heritable component. Despite the availability of current gene-identification techniques, only 5% of all CRCs emerge from well-identifiable inherited causes for predisposition, including polyposis and nonpolyposis syndromes. Hereditary nonpolyposis colorectal cancer represents a large proportion of cases, and robustly affected patients are at increased risk for early onset, synchronous, and metachronous colorectal malignancies and extracolonic malignancies. HNPCC encompasses several cancer syndromes, such as Lynch syndrome, Lynch-like syndrome, and familial colorectal cancer type X, which have remarkable clinical presentations and overlapping genetic profiles that make clinical diagnosis a challenging task. Therefore, distinguishing between the HNPCC disorders is crucial for physicians as an approach to tailor different recommendations for patients and their at-risk family members according to the risks for colonic and extracolonic cancer associated with each syndrome. Identification of these potential patients through epidemiological characteristics and new genetic testing can estimate the individual risk, which informs appropriate cancer screening, surveillance, and/or treatment strategies. In the past three years, many appealing and important advances have been made in our understanding of the relationship between HNPCC and CRC-associated syndromes. The knowledge from the genetic profile of cancer syndromes and unique genotype-phenotype profiles in the different syndromes has changed our cognition. Therefore, this review presents and discusses HNPCC and several common nonpolyposis syndromes with respect to molecular phenotype, histopathologic features, and clinical presentation.

A rare case of Crohn's ileitis in a patient with constitutional mismatch repair deficiency

Constitutional mismatch repair deficiency (CMMRD), a variant of Lynch syndrome, is a rare disease characterized by café-au-lait spots, oligopolyposis, glioblastoma and lymphoma. A 24-year-old male, under surveillance for CMMRD, developed Crohn’s ileitis after total colectomy with end ileostomy for colorectal cancer and failed to respond to oral corticosteroids. The patient underwent induction and maintenance of remission with vedolizumab infusions. We report the first patient with CMMRD developing Crohn’s disease. The choice of immunosuppressive therapy in these patients is challenging and needs to be made according to their risk for malignancy.