Mitotic abnormalities precede microsatellite instability in lynch syndrome-associated colorectal tumourigenesis.

BACKGROUND: Lynch syndrome (LS) is one of the most common hereditary cancer syndromes worldwide. Dominantly inherited mutation in one of four DNA mismatch repair genes combined with somatic events leads to mismatch repair deficiency and microsatellite instability (MSI) in tumours. Due to a high lifetime risk of cancer, regular surveillance plays a key role in cancer prevention; yet the observation of frequent interval cancers points to insufficient cancer prevention by colonoscopy-based methods alone. This study aimed to identify precancerous functional changes in colonic mucosa that could facilitate the monitoring and prevention of cancer development in LS. METHODS: The study material comprised colon biopsy specimens (n = 71) collected during colonoscopy examinations from LS carriers (tumour-free, or diagnosed with adenoma, or diagnosed with carcinoma) and a control group, which included sporadic cases without LS or neoplasia. The majority (80%) of LS carriers had an inherited genetic MLH1 mutation. The remaining 20% included MSH2 mutation carriers (13%) and MSH6 mutation carriers (7%). The transcriptomes were first analysed with RNA-sequencing and followed up with Gorilla Ontology analysis and Reactome Knowledgebase and Ingenuity Pathway Analyses to detect functional changes that might be associated with the initiation of the neoplastic process in LS individuals. FINDINGS: With pathway and gene ontology analyses combined with measurement of mitotic perimeters from colonic mucosa and tumours, we found an increased tendency to chromosomal instability (CIN), already present in macroscopically normal LS mucosa. Our results suggest that CIN is an earlier aberration than MSI and may be the initial cancer driving aberration, whereas MSI accelerates tumour formation. Furthermore, our results suggest that MLH1 deficiency plays a significant role in the development of CIN. INTERPRETATION: The results validate our previous findings from mice and highlight early mitotic abnormalities as an important contributor and precancerous marker of colorectal tumourigenesis in LS. FUNDING: This work was supported by grants from the Jane and Aatos Erkko Foundation, the Academy of Finland (330606 and 331284), Cancer Foundation Finland sr, and the Sigrid Jusélius Foundation. Open access is funded by Helsinki University Library.

Impact of mesorectal extranodal tumor deposits in magnetic resonance imaging on outcome of rectal cancer patients.

AIM: Mesorectal extranodal tumor deposits (TDs) are identified in many rectal cancers. Their radiological features differ from metastatic lymph nodes, and they can be detected with magnetic resonance imaging (MRI). The purpose of this study was to determine the prevalence of rectal cancer TDs detected with MRI and their impact on overall (OS), cancer-specific (CSS), and disease-free survival (DFS) and the local recurrence rate. METHOD: In this retrospective cohort study, we screened all 525 consecutive rectal cancer patients who underwent surgery during 2017-2018 in a tertiary center. Patients with synchronous metastases or who had not undergone MRI were excluded. We analyzed the OS, CSS, and DFS as well as local recurrences. RESULTS: Of the 480 included patients, TDs were detected in the images of 81 (16.9 %). Extramural venous invasion (EMVI) and TDs were frequently found together (n = 50, 61.7 % of all cases with TDs). The presence of TDs alone [hazard ratio (HR) 1.66 (1.03-2.68)] or TDs and/or EMVI [HR 1.63 (1.01-2.62)] were risk factors for adverse DFS in multivariate Cox regression analysis. The OS and CSS rates were poorer among patients with TDs compared to those without, p = 0.009 and p < 0.001, respectively. TDs were also a risk factor for local recurrence in the univariate analysis. CONCLUSIONS: TDs detected with imaging are a risk factor for impaired DFS and associated with impaired CSS and OS of rectal cancer patients and should be taken into consideration in clinical decision-making.

Morbidity After Mechanical Bowel Preparation and Oral Antibiotics Prior to Rectal Resection: The MOBILE2 Randomized Clinical Trial.

Importance: Surgical site infections (SSIs)-especially anastomotic dehiscence-are major contributors to morbidity and mortality after rectal resection. The role of mechanical and oral antibiotics bowel preparation (MOABP) in preventing complications of rectal resection is currently disputed. Objective: To assess whether MOABP reduces overall complications and SSIs after elective rectal resection compared with mechanical bowel preparation (MBP) plus placebo. Design, Setting, and Participants: This multicenter, double-blind, placebo-controlled randomized clinical trial was conducted at 3 university hospitals in Finland between March 18, 2020, and October 10, 2022. Patients aged 18 years and older undergoing elective resection with primary anastomosis of a rectal tumor 15 cm or less from the anal verge on magnetic resonance imaging were eligible for inclusion. Outcomes were analyzed using a modified intention-to-treat principle, which included all patients who were randomly allocated to and underwent elective rectal resection with an anastomosis. Interventions: Patients were stratified according to tumor distance from the anal verge and neoadjuvant treatment given and randomized in a 1:1 ratio to receive MOABP with an oral regimen of neomycin and metronidazole (n = 277) or MBP plus matching placebo tablets (n = 288). All study medications were taken the day before surgery, and all patients received intravenous antibiotics approximately 30 minutes before surgery. Main Outcomes and Measures: The primary outcome was overall cumulative postoperative complications measured using the Comprehensive Complication Index. Key secondary outcomes were SSI and anastomotic dehiscence within 30 days after surgery. Results: In all, 565 patients were included in the analysis, with 288 in the MBP plus placebo group (median [IQR] age, 69 [62-74] years; 190 males [66.0%]) and 277 in the MOABP group (median [IQR] age, 70 [62-75] years; 158 males [57.0%]). Patients in the MOABP group experienced fewer overall postoperative complications (median [IQR] Comprehensive Complication Index, 0 [0-8.66] vs 8.66 [0-20.92]; Wilcoxon effect size, 0.146; P < .001), fewer SSIs (23 patients [8.3%] vs 48 patients [16.7%]; odds ratio, 0.45 [95% CI, 0.27-0.77]), and fewer anastomotic dehiscences (16 patients [5.8%] vs 39 patients [13.5%]; odds ratio, 0.39 [95% CI, 0.21-0.72]) compared with patients in the MBP plus placebo group. Conclusions and Relevance: Findings of this randomized clinical trial indicate that MOABP reduced overall postoperative complications as well as rates of SSIs and anastomotic dehiscences in patients undergoing elective rectal resection compared with MBP plus placebo. Based on these findings, MOABP should be considered as standard treatment in patients undergoing elective rectal resection. Trial Registration: ClinicalTrials.gov Identifier: NCT04281667.

Findings in magnetic resonance imaging for restaging locally advanced rectal cancer.

PURPOSE: We aimed to assess the prognostic value of restaging magnetic resonance imaging (MRI) in rectal cancer after neoadjuvant therapy and compare long-course chemoradiotherapy (LC-CRT) to short-course radiotherapy with delayed surgery (SCRT-delay). METHODS: This retrospective study included 267 patients with locally advanced rectal cancer (LARC) operated on between January 2016 and April 2019, all of whom received either LC-CRT or SCRT-delay in the neoadjuvant setting. The primary outcomes were overall survival (OS) and cancer-specific survival (CSS) based on radiological response assessed using the magnetic resonance tumor regression grade (mrTRG). RESULTS: In the LC-CRT group, cumulative 1-, 3-, and 5-year OS rates were 94.8%, 86.4%, and 79.0%, while in the SCRT-delay group, they were 83.3%, 68.9%, and 68.9% (P = 0.017). For CSS in the LC-CRT group, cumulative rates were 96.9%, 90.3%, and 85.0%, and in the SCRT-delay group, they were 88.6%, 81.4%, and 81.4% (P = 0.222). There were no significant differences in total histological response rates or local recurrence rates between the treatment groups. The good and moderate response group (mrTRG 1-3) had significantly better cumulative 1-, 3-, and 5-year OS and CSS compared to the poorer response group (mrTRG 4-5) (P = 0.023 for OS and P = 0.048 for CSS). CONCLUSION: Unfavorable MRI response is a sign of poor prognosis in LARC. SCRT-delay is comparable to LC-CRT concerning the oncological outcome.

Microbiota and mucosal gene expression of fecal microbiota transplantation or placebo treated patients with chronic pouchitis.

Altered microbiota and impaired host immune function have been linked to the pathogenesis of pouchitis. We used 16S rRNA gene sequencing and RNA sequencing data from a previous randomized clinical trial (RCT) on fecal microbiota transplantation (FMT) therapy in 26 chronic pouchitis patients with one-year follow-up. We analyzed changes in both luminal and mucosal microbiota composition, as well as in host mucosal gene expression to gain insights into the host-microbiota interactions possibly underlying clinical outcomes of the patients. Antibiotic type and pattern of use were significant drivers of the luminal microbiota at baseline. Differential gene expression analysis indicated transition from ileal to colonic gene expression in the pouch, and upregulation in inflammation- and immune system-related pathways in the pouch. At 4 weeks, the non-relapsed FMT patients had a lower microbiota dissimilarity to the donor than the non-relapsed placebo patients (p = .02). While two FMT-treated patients showed a shift toward the donor's microbiota during the one-year follow-up, the overall FMT microbiota modulation effect was low. Patient's luminal and mucosal microbiota profiles were unstable in both FMT and placebo groups. Expression of the chemokine receptor CXCR4 was downregulated at 52 weeks compared to the baseline in the non-relapsed patients in both FMT and placebo groups. Microbiota modulation by FMT seems to be low in this patient group. The microbiota composition or alterations did not explain the relapse status of the patients. Some evidence for remission-related host gene expression pattern was found; specifically, CXCR4 expression may have a role in sustained remission.

Recurrence after cytoreductive surgery and HIPEC for pseudomyxoma peritonei: A single-center retrospective cohort study.

BACKGROUND AND AIMS: Pseudomyxoma peritonei (PMP) is a rare disease characterized by progressive build-up of mucinous deposits inside the abdominal cavity. The aim of this study was to investigate the effect of disease recurrence on overall survival in patients with PMP after cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC). METHODS: One-hundred thirty-two consecutive PMP patients treated with CRS + HIPEC at Helsinki University Hospital between 2008 and 2017 were included. The impact of clinicopathological and treatment-related characteristics on recurrence and overall survival was evaluated. RESULTS: The median follow-up time in the study was 5.04 (range = 0.05-11.60) years. In 121 (91.7%) patients, the disease was classified as low grade and 11 (8.3%) had high-grade disease. In the low-grade group, 26 (21.5%) patients developed a recurrence during follow-up compared to 6 (54.5%) patients in the high-grade group. In the low-grade group, cumulative survival was 98.2%, 91.4%, and 91.4% at 3, 6, and 8 years, respectively. In the high-grade group, cumulative survival was 90.0% and 78.8% at 3 and 6 years, respectively. In patients with recurrent disease, the cumulative survival was 100%, 84.6%, and 84.6% at 3, 6, and 8 years in the low-grade category and 80.0% and 60.0% at 3 and 6 years in the high-grade category, respectively. In the low-grade group, a statistically significant correlation with recurrence but not with overall survival was identified with peritoneal cancer index (PCI), carcinoembryonic antigen (CEA), and the number of affected regions. CONCLUSION: The recurrence of low-grade PMP does not significantly affect overall survival of patients. Disease extent may not be a prognostic indicator after curative CRS and HIPEC in low-grade PMP.

Tumor-independent Detection of Inherited Mismatch Repair Deficiency for the Diagnosis of Lynch Syndrome with High Specificity and Sensitivity.

Lynch syndrome (LS) is the most common hereditary cancer syndrome. Early diagnosis improves prognosis and reduces health care costs, through existing cancer surveillance methods. The problem is finding and diagnosing the cancer predisposing genetic condition. The current workup involves a complex array of tests that combines family cancer history and clinical phenotypes with tumor characteristics and sequencing data, followed by a challenging task to interpret the found variant(s). On the basis of the knowledge that an inherited mismatch repair (MMR) deficiency is a hallmark of LS, we have developed and validated a functional MMR test, DiagMMR, that detects inherited MMR deficiency directly from healthy tissue without need of tumor and variant information. The validation included 119 skin biopsies collected from clinically pathogenic MMR variant carriers (MSH2, MSH6) and controls, and was followed by a small clinical pilot study. The repair reaction was performed on proteins extracted from primary fibroblasts and the interpretation was based on the MMR capability of the sample in relation to cutoff, which distinguishes MMR proficient (non-LS) from MMR deficient (LS) function. The results were compared with the reference standard (germline NGS). The test was shown to have exceptional specificity (100%) with high sensitivity (89%) and accuracy (97%). The ability to efficiently distinguish LS carriers from controls was further shown with a high area under the receiving operating characteristic (AUROC) value (0.97). This test offers an excellent tool for detecting inherited MMR deficiency linked to MSH2 or MSH6 and can be used alone or with conventional tests to recognize genetically predisposed individuals. Significance: Clinical validation of DiagMMR shows high accuracy in distinguishing individuals with hereditary MSH2 or MSH6 MMR deficiency (i.e., LS). The method presented overcomes challenges faced by the complexity of current methods and can be used alone or with conventional tests to improve the ability to recognize genetically predisposed individuals.

The ability of magnetic resonance imaging to predict lymph node metastases and the risk of recurrence in rectal cancer.

AIM: This study aimed to examine the diagnostic accuracy and prognostic value of magnetic resonance imaging (MRI) detected lymph nodes in rectal cancer. METHOD: We evaluated 806 rectal cancer patients consecutively operated on between 2015 and 2018 at Helsinki University Hospital. In total, 485 patients met the inclusion criteria of presenting with stage I-III disease and were intended for curative treatment at the time of diagnosis. The effect of MRI-detected clinical lymph node status (cN) on cumulative overall survival (OS), disease-specific survival (DSS) and disease-free survival (DFS) was calculated using the Kaplan-Meier analysis. RESULTS: Negative predictive value (NPV) of MRI-lymphnode negativity was 74.8%. Positive predictive value of lymph node metastasis was only 48.6%. In the Kaplan-Meier survival analysis, OS (p = 0.989), DSS (p = 0.911), and DFS (p = 0.109) did not significantly differ according to MRI nodal status. However, cumulative disease-free survival significantly (p < 0.001) differed according to the histopathological lymph node metastasis status (pN). CONCLUSIONS: MRI detected lymph node positivity appears insufficiently precise and cannot predict disease recurrence or survival. Therefore, it should not serve as an independent risk factor when considering neoadjuvant treatment options for rectal cancer patients.

Systemic circulating microRNA landscape in Lynch syndrome.

Circulating microRNAs (c-miRs) are small noncoding RNA molecules that migrate throughout the body and regulate gene expression. Global c-miR expression patterns (c-miRnomes) change with sporadic carcinogenesis and have predictive potential in early detection of cancers. However, there are no studies that have assessed whether c-miRnomes display similar potential in carriers of inherited pathogenic mismatch-repair gene variants (path_MMR), known as Lynch syndrome (LS), who are predisposed to highly increased cancer risk. Using high-throughput sequencing and bioinformatic approaches, we conducted an exploratory analysis to characterize systemic c-miRnomes of path_MMR carriers, sporadic rectal cancer patients and non-LS controls. We showed for the first time that cancer-free path_MMR carriers have a systemic c-miRnome of 40 differentially expressed c-miRs that can distinguish them from non-LS controls. The systemic c-miRnome of cancer-free path_MMR carriers also resembles the systemic c-miRnomes of cancer patients with or without path_MMR. Our pathway analysis linked the found differentially expressed c-miRs to carcinogenesis. A total of 508 putative target genes were identified for 32 out of 40 differentially expressed c-miRs, and 238 of them were enriched in cancer-related pathways. The most enriched c-miR-target genes include well-known oncogenes and tumor suppressor genes such as BCL2, AKT3, PIK3CA, KRAS, NRAS, CDKN1A and PIK3R1. Taken together, our findings suggest that LS and sporadic carcinogenesis share common biological pathways and alterations in these pathways can produce a c-miR signature which can track potential oncogenic stress in cancer-free path_MMR carriers. Therefore, c-miRs hold potential in monitoring the LS risk stratification patterns during clinical surveillance or cancer management.

Short- and Long-Term Survival among Elderly Colorectal Cancer Patients in Finland, 2006-2015: A Nationwide Population-Based Registry Study.

This population-based registry study aimed to report 30-day and one-year postoperative survival, five-year overall survival (OS), and disease-specific survival (DSS) among elderly (≥75 years old) colorectal cancer (CRC) patients. All new colorectal cancer cases from 2006-2015 were included and followed until death or the end of follow-up (end of 2016). Among 27,088 CRC patients, 11,306 patients were ≥75 years old. Among patients ≥ 75 years, 36.8% (n = 4160) had right-sided colon cancer, 21.9% (n = 2478) left-sided colon cancer, and 32.3% (n = 3650) rectal cancer. In this study population, 932 patients were aged ≥ 90. The 30-day postoperative OS for patients aged 75-79 was 96.1% (95% confidence interval [CI] 95.3-96.9) falling to 93.2% (95% CI 92.0-94.4) for patients aged 80-84. The one-year postoperative OS among patients aged 75-79 was 86.3% (95% CI 84.7-87.9) compared with 80.5% (95% CI 78.7-82.3) among patients aged 80-84. Five-year OS among patients aged 75-79 was 47.6% (95% CI 46.0-49.2) and 36.6% (95% CI 34.8-38.4) among patients aged 80-84, compared with 61.7% (95% CI 60.9-62.5) among younger patients (<75 years old). Survival among elderly CRC patients (≥75 years old) was in general fairly good when compared with younger patients, especially among patients aged 75-79 and 80-84 with localized or locally advanced disease.

Mono- and biallelic germline variants of DNA glycosylase genes in colon adenomatous polyposis families from two continents.

Recently, biallelic germline variants of the DNA glycosylase genes MUTYH and NTHL1 were linked to polyposis susceptibility. Significant fractions remain without a molecular explanation, warranting searches for underlying causes. We used exome sequencing to investigate clinically well-defined adenomatous polyposis cases and families from Finland (N=34), Chile (N=21), and Argentina (N=12), all with known susceptibility genes excluded. Nine index cases (13%) revealed germline variants with proven or possible pathogenicity in the DNA glycosylase genes, involving NEIL1 (mono- or biallelic) in 3 cases, MUTYH (monoallelic) in 3 cases, NTHL1 (biallelic) in 1 case, and OGG1 (monoallelic) in 2 cases. NTHL1 was affected with the well-established, pathogenic c.268C>T, p.(Gln90Ter) variant. A recurrent heterozygous NEIL1 c.506G>A, p.(Gly169Asp) variant was observed in two families. In a Finnish family, the variant occurred in trans with a truncating NEIL1 variant (c.821delT). In an Argentine family, the variant co-occurred with a genomic deletion of exons 2 - 11 of PMS2. Mutational signatures in tumor tissues complied with biological functions reported for NEIL1. Our results suggest that germline variants in DNA glycosylase genes may occur in a non-negligible proportion of unexplained colon polyposis cases and may predispose to tumor development.

Prevalence, Cell Tropism, and Clinical Impact of Human Parvovirus Persistence in Adenomatous, Cancerous, Inflamed, and Healthy Intestinal Mucosa.

Parvoviruses are single-stranded DNA viruses, infecting many animals from insects to humans. Human parvovirus B19 (B19V) causes erythema infectiosum, arthropathy, anemia, and fetal death, and human bocavirus (HBoV) 1 causes respiratory tract infections, while HBoV2-4 are enteric. Parvoviral genomes can persist in diverse non-permissive tissues after acute infection, but the host-cell tropism and the impact of their tissue persistence are poorly studied. We searched for parvoviral DNA in a total of 427 intestinal biopsy specimens, as paired disease-affected and healthy mucosa, obtained from 130 patients with malignancy, ulcerative colitis (UC), or adenomas, and in similar intestinal segments from 55 healthy subjects. Only three (1.6%) individuals exhibited intestinal HBoV DNA (one each of HBoV1, 2, and 3). Conversely, B19V DNA persisted frequently in the intestine, with 50, 47, 31, and 27% detection rates in the patients with malignancy, UC, or adenomas, and in the healthy subjects, respectively. Intra-individually, B19V DNA persisted significantly more often in the healthy intestinal segments than in the inflamed colons of UC patients. The highest loads of B19V DNA were seen in the ileum and colon specimens of two healthy individuals. With dual-RNAscope in situ hybridization and immunohistochemistry assays, we located the B19V persistence sites of these intestines in mucosal B cells of lymphoid follicles and vascular endothelial cells. Viral messenger RNA transcription remained, however, undetected. RNA sequencing (RNA-seq) identified 272 differentially expressed cellular genes between B19V DNA-positive and -negative healthy ileum biopsy specimens. Pathway enrichment analysis revealed that B19V persistence activated the intestinal cell viability and inhibited apoptosis. Lifelong B19V DNA persistence thus modulates host gene expression, which may lead to clinical outcomes.

Long-term survival among colorectal cancer patients in Finland, 1991-2015: a nationwide population-based registry study.

BACKGROUND: Colorectal cancer (CRC) incidence in Finland has risen steadily. Given development in cancer treatments in recent decades, disease-specific data on the long-term prognosis of patients may be obsolete. Thus, this study aimed to report 5-year disease-specific survival (DSS) and relative survival based on tumour spread and site among CRC patients diagnosed between 1991 and 2015 in Finland. MATERIAL AND METHODS: We conducted a population-based registry study among 59 465 CRC patients identified from the Finnish Cancer Registry. RESULTS: The 5-year DSS for all CRC patients was 56.7% [95% confidence interval (CI) 56.3-57.1%] for 1991 through 2015. Tumour site-specific survival has improved for the period 2006-2015 versus 1991-2005 for right-sided colon cancer from 54.8% (95% CI 53.8-55.8%) to 59.9% (95% CI 58.7-61.1%), for left-sided colon cancer from 54.1% (95% CI 52.9-55.3%) to 61.0% (95% CI 59.8-62.2%) and for rectal cancer from 53.6% (95% CI 52.2-55.0%) to 62.3% (95% CI 61.3-63.3%). The 5-year relative survival for the period 2006 through 2015 was 93.6% for localised disease (stage I); 84.2% for locally advanced tumour invading adjacent structures (stage II); 68.2% for regional disease with regional lymph node metastases (stage III); and 14.0% for metastatic disease (stage IV). CONCLUSIONS: This study confirms that survival for CRC has improved in recent decades in Finland, mirroring observations from other Western countries. However, the classification of tumour spread within the Finnish Cancer Registry differs slightly from the TNM classification, thereby limiting the generalisability of these results.

The prognostic value of extramural venous invasion in preoperative MRI of rectal cancer patients.

AIM: This study aimed to examine the prognostic value of extramural venous invasion observed in preoperative MRI on survival and recurrences. METHOD: In total, 778 rectal cancer patients were evaluated in multidisciplinary meetings in Helsinki University Hospital during the years 2016-2018. 635 patients met the inclusion criteria of stage I-III disease and were intended for curative treatment at the time of diagnosis. 128 had extramural venous invasion in preoperative MRI. RESULTS: The median follow-up time was 2.5 years. In a univariate analysis extramural venous invasion was associated with poorer disease-specific survival (hazard ratio [HR] 2.174, 95% CI 1.118-4.224, P = 0.022), whereas circumferential margin ≤1 mm, tumour stage ≥T3c or nodal positivity were not. Disease recurrence occurred in 17.3% of the patients: 13.4% had metastatic recurrence only, 1.7% mere local recurrence and 2.2% both metastatic and local recurrence. In multivariate analysis, extramural venous invasion (HR 1.734, 95% CI 1.127-2.667, P = 0.012) and nodal positivity (HR 1.627, 95% CI 1.071-2.472, P = 0.023) were risk factors for poorer disease-free survival (DFS). Circumferential margin ≤1 mm was a risk factor for local recurrence in multivariate analysis (HR 5.675, 95% CI 1.274-25.286, P = 0.023). CONCLUSION: In MRI, circumferential margin ≤1 mm is a risk factor for local recurrence, but the risk is quite well controlled with chemoradiotherapy and extended surgery. Extramural venous invasion instead is a significant risk factor for poorer DFS and new tools to reduce the systemic recurrence risk are needed.

Immunoprofiles and DNA Methylation of Inflammatory Marker Genes in Ulcerative Colitis-Associated Colorectal Tumorigenesis.

Immunological and epigenetic changes are interconnected and contribute to tumorigenesis. We determined the immunoprofiles and promoter methylation of inflammation-related genes for colitis-associated colorectal carcinomas (CA-CRC). The results were compared with Lynch syndrome (LS)-associated colorectal tumors, which are characterized by an active immune environment through inherited mismatch repair defects. CA-CRCs (n = 31) were immunohistochemically evaluated for immune cell scores (ICSs) and PDCD1 and CD274 expression. Seven inflammation-associated genes (CD274, NTSR1, PPARG, PTGS2, PYCARD, SOCS1, and SOCS2), the repair gene MGMT, and eight standard marker genes for the CpG Island Methylator Phenotype (CIMP) were investigated for promoter methylation in CA-CRCs, LS tumors (n = 29), and paired normal mucosae by multiplex ligation-dependent probe amplification. All but one CA-CRCs were microsatellite-stable and all LS tumors were microsatellite-unstable. Most CA-CRCs had a high ICS (55%) and a positive CD274 expression in immune cells (52%). NTSR1 revealed frequent tumor-specific hypermethylation in CA-CRC and LS. When compared to LS mucosae, normal mucosae from patients with CA-CRC showed significantly higher methylation of NTSR1 and most CIMP markers. In conclusion, CA-CRCs share a frequent ICShigh/CD274pos expression pattern with LS tumors. Elevated methylation in normal mucosa may indicate field cancerization as a feature of CA-CRC-associated tumorigenesis.

Repeated centralized multidisciplinary team assessment of resectability, clinical behavior, and outcomes in 1086 Finnish metastatic colorectal cancer patients (RAXO): A nationwide prospective intervention study.

BACKGROUND: Resection of colorectal cancer (CRC) metastases provides good survival but is probably underused in real-world practice. METHODS: A prospective Finnish nationwide study enrolled treatable metastatic CRC patients. The intervention was the assessment of resectability upfront and twice during first-line therapy by the multidisciplinary team (MDT) at Helsinki tertiary referral centre. The primary outcome was resection rates and survival. FINDINGS: In 2012-2018, 1086 patients were included. Median follow-up was 58 months. Multiple metastatic sites were present in 500 (46%) patients at baseline and in 820 (76%) during disease trajectory. In MDT assessments, 447 (41%) were classified as resectable, 310 (29%) upfront and 137 (18%) after conversion therapy. Six-hundred and ninety curative intent resections or local ablative therapies (LAT) were performed in 399 patients (89% of 447 resectable). Multiple metastasectomies for multisite or later developing metastases were performed in 148 (37%) patients. Overall, 414 liver, 112 lung, 57 peritoneal, and 107 other metastasectomies were performed. Median OS was 80·4 months in R0/1-resected (HR 0·15; CI95% 0·12-0·19), 39·1 months in R2-resected/LAT (0·39; 0·29-0·53) patients, and 20·8 months in patients treated with "systemic therapy alone" (reference), with 5-year OS rates of 66%, 40%, and 6%, respectively. INTERPRETATION: Repeated centralized MDT assessment in real-world metastatic CRC patients generates high resectability (41%) and resection rates (37%) with impressive survival, even when multisite metastases are present or develop later. FUNDING: The funders had no role in the study design, analysis, and interpretation of the data or writing of this report.

Distinct Mutational Profile of Lynch Syndrome Colorectal Cancers Diagnosed under Regular Colonoscopy Surveillance.

Regular colonoscopy even with short intervals does not prevent all colorectal cancers (CRC) in Lynch syndrome (LS). In the present study, we asked whether cancers detected under regular colonoscopy surveillance (incident cancers) are phenotypically different from cancers detected at first colonoscopy (prevalent cancers). We analyzed clinical, histological, immunological and mutational characteristics, including panel sequencing and high-throughput coding microsatellite (cMS) analysis, in 28 incident and 67 prevalent LS CRCs (n total = 95). Incident cancers presented with lower UICC and T stage compared to prevalent cancers (p < 0.0005). The majority of incident cancers (21/28) were detected after previous colonoscopy without any pathological findings. On the molecular level, incident cancers presented with a significantly lower KRAS codon 12/13 (1/23, 4.3% vs. 11/21, 52%; p = 0.0005) and pathogenic TP53 mutation frequency (0/17, 0% vs. 7/21, 33.3%; p = 0.0108,) compared to prevalent cancers; 10/17 (58.8%) incident cancers harbored one or more truncating APC mutations, all showing mutational signatures of mismatch repair (MMR) deficiency. The proportion of MMR deficiency-related mutational events was significantly higher in incident compared to prevalent CRC (p = 0.018). In conclusion, our study identifies a set of features indicative of biological differences between incident and prevalent cancers in LS, which should further be monitored in prospective LS screening studies to guide towards optimized prevention protocols.

Mechanical bowel preparation and oral antibiotics versus mechanical bowel preparation only prior rectal surgery (MOBILE2): a multicentre, double-blinded, randomised controlled trial-study protocol.

INTRODUCTION: Mechanical bowel preparation (MBP) prior to rectal surgery is widely used. Based on retrospective data many guidelines recommend mechanical and oral antibiotic bowel preparation (MOABP) to reduce postoperative complications and specifically surgical site infections (SSIs). The primary aim of this study is to examine whether MOABP reduces complications of rectal surgery. METHODS AND ANALYSIS: The MOBILE2 (Mechanical Bowel Preparation and Oral Antibiotics vs Mechanical Bowel Preparation Only Prior Rectal Surgery) trial is a multicentre, double-blinded, parallel group, superiority, randomised controlled trial comparing MOABP to MBP among patients scheduled for rectal surgery with colorectal or coloanal anastomosis. The patients randomised to the MOABP group receive 1 g neomycin and 1 g metronidazole two times on a day prior to surgery and patients randomised to the MBP group receive identical placebo. Based on power calculations, 604 patients will be enrolled in the study. The primary outcome is Comprehensive Complication Index within 30 days after surgery. Secondary outcomes are SSIs within 30 days after surgery, the number and classification of anastomosis dehiscences, the length of hospital stay, mortality within 90 days after surgery and the number of patients who received adjuvant treatment if needed. Tertiary outcomes are overall survival, disease-specific survival, recurrence-free survival and difference in quality-of-life before and 1 year after surgery. In addition, the microbiota differences in colon mucosa are analysed. ETHICS AND DISSEMINATION: The Ethics Committee of Helsinki University Hospital approved the study. The findings will be disseminated in peer-reviewed academic journals. TRIAL REGISTRATION NUMBER: NCT04281667.

Genetic and Epigenetic Characteristics of Inflammatory Bowel Disease-Associated Colorectal Cancer.

BACKGROUND & AIMS: Inflammatory bowel disease (IBD) is a chronic, relapsing inflammatory disorder associated with an elevated risk of colorectal cancer (CRC). IBD-associated CRC (IBD-CRC) may represent a distinct pathway of tumorigenesis compared to sporadic CRC (sCRC). Our aim was to comprehensively characterize IBD-associated tumorigenesis integrating multiple high-throughput approaches, and to compare the results with in-house data sets from sCRCs. METHODS: Whole-genome sequencing, single nucleotide polymorphism arrays, RNA sequencing, genome-wide methylation analysis, and immunohistochemistry were performed using fresh-frozen and formalin-fixed tissue samples of tumor and corresponding normal tissues from 31 patients with IBD-CRC. RESULTS: Transcriptome-based tumor subtyping revealed the complete absence of canonical epithelial tumor subtype associated with WNT signaling in IBD-CRCs, dominated instead by mesenchymal stroma-rich subtype. Negative WNT regulators AXIN2 and RNF43 were strongly down-regulated in IBD-CRCs and chromosomal gains at HNF4A, a negative regulator of WNT-induced epithelial-mesenchymal transition (EMT), were less frequent compared to sCRCs. Enrichment of hypomethylation at HNF4α binding sites was detected solely in sCRC genomes. PIGR and OSMR involved in mucosal immunity were dysregulated via epigenetic modifications in IBD-CRCs. Genome-wide analysis showed significant enrichment of noncoding mutations to 5'untranslated region of TP53 in IBD-CRCs. As reported previously, somatic mutations in APC and KRAS were less frequent in IBD-CRCs compared to sCRCs. CONCLUSIONS: Distinct mechanisms of WNT pathway dysregulation skew IBD-CRCs toward mesenchymal tumor subtype, which may affect prognosis and treatment options. Increased OSMR signaling may favor the establishment of mesenchymal tumors in patients with IBD.