See Covering the Cover synopsis on page 380.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 WNTinduced epithelial-mesenchymal transition (EMT), were less frequent compared to sCRCs. Enrichment of hypomethylation at HNF4a binding sites was detected solely in sCRC genomes.

Increasing evidence suggests that cancer progression is strongly influenced by host immune response, which is represented by immune cell infiltrates. T-lymphocyte-based immunoscore has proved to be a prognostic factor in colon cancer, but its significance in pancreatic cancer is poorly known. Total of 108 patients operated (R0/R1) for pancreatic ductal adenocarcinoma (PDAC) (TNM stage I-II) were included in the study. Immune cell score (IS) was determined by scoring the samples from grade 0 to 4 according to the number of immune cells (CD3 and CD8) in tumor core and invasion margin using tissue microarrays, immunohistochemistry, and digital analysis. Tumors with microsatellite instability were identified by MLH1 immunostaining. High IS and low histological grade were significantly associated with better disease-specific survival (DSS) and overall survival (OS). The 5-year DSS rate for low, moderate, and high IS groups were 5.0, 15.2, and 33.4%, respectively (p = 0.007). The 5-year OS rate for the low, moderate, and high IS groups were 4.2, 13.4, and 31.5%, respectively (p = 0.004). In addition, IS and prognosis varied within a single TNM stage. There was no association between IS and any of the clinicopathological variables. IS was shown to be an independent prognostic factor for better DSS and OS in multivariate analysis, together with the histological grade of the tumor and perineural invasion. Five MLH1-negative tumors (4.6%) were found showing no correlation with IS. IS could be a useful prognostic marker in patients with PDAC treated by primary surgery.

The aim of this study was to investigate immune response and its prognostic significance in colon carcinomas using the previously described Immunoscore (IS). A population‐based series of 779 colorectal cancers, operated on between 2000 and 2010, were classified according to tumour, node, metastasis (TNM) status, mismatch repair (MMR), and BRAF mutation status. Rectal cancer cases (n = 203) were excluded as a high proportion of these patients received preoperative neoadjuvant chemoradiotherapy. Tissue microarray (TMA) samples collected from the tumour centre and invasive front were immunostained for CD3 and CD8. Lymphocytes were then digitally calculated to categorize IS from grade 0 to 4. Samples adequate for IS were available from 510 tumours. IS was significantly associated with AJCC/UICC stage, T stage, lymph node and distant metastases, perineural and lymphovascular invasion, MMR status, and BRAF mutation status. For IS0, IS1, IS2, IS3 and IS4, respectively, the 5‐year disease‐free survival (DFS) rates were 59, 68, 78, 83 and 94% (p < 0.001); 5‐year disease‐specific survival (DSS) rates were 47, 55, 75, 80, and 89% (p < 0.001); and 5‐year overall survival (OS) rates were 40, 44, 66, 61, and 76% (p < 0.001). IS was also prognostic for DFS, DSS, and OS within subsets of microsatellite‐stable (MSS) and microsatellite‐instable (MSI) disease. Multivariable analysis showed that IS, AJCC/UICC stage, lymphovascular invasion, and lymph node ratio in AJCC/UICC stage III disease were independent prognostic factors for DFS, DSS, and OS. Age was an independent prognostic factor for DSS and OS. Gender and BRAF mutation were independent prognostic factors for OS. In conclusion, IS differentiated patients with poor versus improved prognosis in MSS and MSI disease and across AJCC/UICC stages. IS, AJCC/UICC stage, lymphovascular invasion, and lymph node ratio in AJCC/UICC stage III disease were independent prognostic factors for DFS, DSS, and OS.

Background: This population-based study aimed to examine the incidence, patterns and results of multimodal management of metastatic colorectal cancer. Methods: A retrospective population-based study was conducted on patients with metastatic colorectal cancer in Central Finland in 2000-2015. Clinical and histopathological data were retrieved and descriptive analysis was conducted to determine the pattern of metastatic disease, defined as synchronous, early metachronous (within 12 months of diagnosis of primary disease) and late metachronous (more than 12 months after diagnosis). Subgroups were compared for resection and overall survival (OS) rates. Results: Of 1671 patients, 296 (17⋅7 per cent) had synchronous metastases, and 255 (19⋅6 per cent) of 1302 patients with resected stage I-III tumours developed metachronous metastases (94 early and 161 late metastases). Liver, pulmonary and intraperitoneal metastases were the most common sites. The commonest metastatic patterns were a combination of liver and lung metastases. The overall metastasectomy rate for patients with synchronous metastases was 16⋅2 per cent; in this subgroup, 3and 5-year OS rates after any resection were 63 and 44 per cent respectively, compared with 7⋅1 and 3⋅3 per cent following no resection (P < 0⋅001). The resection rate was higher for late than for early metachronous disease (28⋅0 versus 17 per cent respectively; P = 0⋅048). Three-and 5-year OS rates after any resection of metachronous metastases were 78 and 62 per cent respectively versus 42⋅1 and 18⋅2 per cent with no metastasectomy (P < 0⋅001). Similarly, 3-and 5-year OS rates after any metastasectomy for early metachronous metastases were 57 and 50 per cent versus 84 and 66 per cent for late metachronous metastases (P = 0⋅293). Conclusion: The proportion of patients with metastatic colorectal cancer was consistent with that in earlier population-based studies, as were resection rates for liver and lung metastases and survival after resection. Differentiation between synchronous, early and late metachronous metastases can improve assessment of resectability and survival.

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