The average age at diagnosis for colorectal cancer (CRC) in Australia is 69, and the age‐specific incidence rises rapidly after age 50 years. The incidence has stabilized or is declining in older age ...groups in Australia during recent decades, possibly related to the increased uptake of screening and high‐risk surveillance. In the same time frame, a rising incidence of CRC in younger adults has been well‐documented in the United States. This rise in incidence in the young has not been reported from other countries that share long‐term exposure to westernised urban lifestyles. Using data from the Australian Institute of Health and Welfare, we examined trends in national incidence rates for CRC under age 50 years and observed that rates in people under age 40 years have been rising for the last two decades. We further performed a review of the literature regarding CRC in young adults to outline the extent of current understanding, explore potential risk factors such as obesity, alcohol, and sedentary lifestyles, and to identify the questions remaining to be addressed. Although absolute numbers might not justify a population screening approach, the dispersal of young adults with CRC across the primary health‐care system decreases probability of their recognition. Patient and physician awareness, aided by stool and emerging blood‐screening tests and risk profiling tools, have the potential to aid in identification of those young adults who would most benefit from a colonoscopy through early detection of CRCs or by removal of advanced polyps.
Histopathology is an emerging treatment target in ulcerative colitis (UC) clinical trials. Our aim was to provide guidance on standardizing biopsy collection protocols, identifying optimal evaluative ...indices, and defining thresholds for histologic response and remission after treatment.
An international, interdisciplinary expert panel of 19 gastroenterologists and gastrointestinal pathologists was assembled. A modified RAND/University of California, Los Angeles appropriateness methodology was used to address relevant issues. A total of 138 statements were derived from a systematic review of the literature and expert opinion. Each statement was anonymously rated as appropriate, uncertain, or inappropriate using a 9-point scale. Survey results were reviewed and discussed before a second round of voting.
Histologic measurements collected using a uniform biopsy strategy are important for assessing disease activity and determining therapeutic efficacy in UC clinical trials. Multiple biopsy strategies were deemed acceptable, including segmental biopsies collected according to the endoscopic appearance. Biopsies should be scored for architectural change, lamina propria chronic inflammation, basal plasmacytosis, lamina propria and epithelial neutrophils, epithelial damage, and erosions/ulcerations. The Geboes score, Robarts Histopathology Index, and Nancy Index were considered appropriate for assessing histologic activity; use of the modified Riley score and Harpaz Index were uncertain. Histologic activity at baseline should be required for enrollment, recognizing this carries operational implications. Achievement of histologic improvement or remission was considered an appropriate and realistic therapeutic target. Current histologic indices require validation for pediatric populations.
These recommendations provide a framework for standardized implementation of histopathology in UC trials. Additional work is required to address operational considerations and areas of uncertainty.
We studied 2332 individuals with monoallelic mutations in MUTYH among 9504 relatives of 264 colorectal cancer (CRC) cases with a MUTYH mutation. We estimated CRC risks through 70 years of age of 7.2% ...for male carriers of monoallelic mutations (95% confidence interval CI, 4.6%–11.3%) and 5.6% for female carriers of monoallelic mutations (95% CI, 3.6%–8.8%), irrespective of family history. For monoallelic MUTYH mutation carriers with a first-degree relative with CRC diagnosed by 50 years of age who does not have the MUTYH mutation, risks of CRC were 12.5% for men (95% CI, 8.6%–17.7%) and 10% for women (95% CI, 6.7%–14.4%). Risks of CRC for carriers of monoallelic mutations in MUTYH with a first-degree relative with CRC are sufficiently high to warrant more intensive screening than for the general population.
Germline pathogenic variants (PVs) in the DNA mismatch repair (MMR) genes and in the base excision repair gene
underlie hereditary colorectal cancer (CRC) and polyposis syndromes. We evaluated the ...robustness and discriminatory potential of tumour mutational signatures in CRCs for identifying germline PV carriers.
Whole-exome sequencing of formalin-fixed paraffin-embedded (FFPE) CRC tissue was performed on 33 MMR germline PV carriers, 12 biallelic
germline PV carriers, 25 sporadic
methylated MMR-deficient CRCs (MMRd controls) and 160 sporadic MMR-proficient CRCs (MMRp controls) and included 498 TCGA CRC tumours. COSMIC V3 single base substitution (SBS) and indel (ID) mutational signatures were assessed for their ability to differentiate CRCs that developed in carriers from non-carriers.
The combination of mutational signatures SBS18 and SBS36 contributing >30% of a CRC's signature profile was able to discriminate biallelic
carriers from all other non-carrier control CRCs with 100% accuracy (area under the curve (AUC) 1.0). SBS18 and SBS36 were associated with specific
variants p.Gly396Asp (p=0.025) and p.Tyr179Cys (p=5×10
), respectively. The combination of ID2 and ID7 could discriminate the 33 MMR PV carrier CRCs from the MMRp control CRCs (AUC 0.99); however, SBS and ID signatures, alone or in combination, could not provide complete discrimination (AUC 0.79) between CRCs from MMR PV carriers and sporadic MMRd controls.
Assessment of SBS and ID signatures can discriminate CRCs from biallelic
carriers and MMR PV carriers from non-carriers with high accuracy, demonstrating utility as a potential diagnostic and variant classification tool.
To examine whether quantitative pathologic analysis of digitized hematoxylin and eosin slides of colorectal carcinoma (CRC) correlates with clinicopathologic features, molecular alterations, and ...prognosis.
A quantitative segmentation algorithm (QuantCRC) was applied to 6468 digitized hematoxylin and eosin slides of CRCs. Fifteen parameters were recorded from each image and tested for associations with clinicopathologic features and molecular alterations. A prognostic model was developed to predict recurrence-free survival using data from the internal cohort (n = 1928) and validated on an internal test (n = 483) and external cohort (n = 938).
There were significant differences in QuantCRC according to stage, histologic subtype, grade, venous/lymphatic/perineural invasion, tumor budding, CD8 immunohistochemistry, mismatch repair status, KRAS mutation, BRAF mutation, and CpG methylation. A prognostic model incorporating stage, mismatch repair, and QuantCRC resulted in a Harrell’s concordance (c)-index of 0.714 (95% confidence interval CI, 0.702–0.724) in the internal test and 0.744 (95% CI, 0.741–0.754) in the external cohort. Removing QuantCRC from the model reduced the c-index to 0.679 (95% CI, 0.673–0.694) in the external cohort. Prognostic risk groups were identified, which provided a hazard ratio of 2.24 (95% CI, 1.33–3.87, P = .004) for low vs high-risk stage III CRCs and 2.36 (95% CI, 1.07–5.20, P = .03) for low vs high-risk stage II CRCs, in the external cohort after adjusting for established risk factors. The predicted median 36-month recurrence rate for high-risk stage III CRCs was 32.7% vs 13.4% for low-risk stage III and 15.8% for high-risk stage II vs 5.4% for low-risk stage II CRCs.
QuantCRC provides a powerful adjunct to routine pathologic reporting of CRC. A prognostic model using QuantCRC improves prediction of recurrence-free survival.
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We demonstrate that quantitative analysis of digitized images of colorectal carcinoma can improve prediction of tumor recurrence and place tumors into clinically relevant prognostic risk groups.
Tropical sprue is an acquired chronic diarrheal disorder of unclear etiology affecting residents of and visitors to tropical regions. Patients usually present with profuse diarrhea, weight loss, and ...malabsorption, notably of vitamin B12 and folate. The histologic changes typically resemble that of gluten-sensitive enteropathy. Reports of tropical sprue have become infrequent in the literature, and the diagnosis is often not considered either clinically or pathologically. This disease may, however, cause significant morbidity, although it is eminently treatable with broad-spectrum antibiotics. In this study, we report the clinical presentation of 12 tropical sprue patients along with the histologic changes of the intestinal mucosa and compare it with those of a series of 150 cases of gluten-sensitive enteropathy, the condition with which it is most frequently misdiagnosed. The cohort comprised 6 men and 6 women with a median age of 59 years (range, 38 to 78 y) with a history of residence or visitation in South Asia or Papua New Guinea. Partial villous blunting in the duodenal mucosa was present in 75% of cases, and a marked intraepithelial lymphocytosis was observed in all cases (mean per 100 epithelial cells 77.3; range, 42 to 124). A villous tip accentuation of intraepithelial lymphocytosis was not appreciable in most cases. No case of complete villous blunting (Marsh stage 3c) was identified in tropical sprue, contrasting with 25% in gluten-sensitive enteropathy cases. A duodenal mucosa eosinophil infiltrate was present in all cases with significantly higher counts compared with untreated gluten-sensitive enteropathy patients (26.6/HPF vs. 14.6/HPF; P=0.009). The ileal mucosa displayed more severe villous blunting with higher Marsh stages than in the corresponding duodenum from 5 patients. There was a mild intraepithelial lymphocytosis and eosinophil infiltrate in the colonic mucosa of half of the cases. Follow-up biopsies in 6 patients demonstrated a histologic response after oral folates and doxycycline treatment. In summary, tropical sprue is a pan-enteric inflammatory process often mistaken for gluten-sensitive enteropathy. Histologic findings suggesting tropical sprue in the appropriate clinical context include incomplete duodenal villous blunting without development of flat mucosa, frequent involvement of the terminal ileum with more marked inflammation and villous blunting than in the duodenum, and a conspicuous eosinophil infiltrate in the lamina propria. With the expansion of tourism and increasing employment opportunities in tropical regions, pathologists in the West are increasingly likely to encounter cases of tropical sprue and should be aware of this diagnosis.
Mucinous differentiation is associated with both CpG island methylator phenotype and microsatellite instability in colorectal cancer. The mucinous phenotype derives from abundant expression of the ...colonic goblet cell mucin, MUC2, and de novo expression of gastric foveolar mucin, MUC5AC. We, therefore, investigated the protein expression levels of MUC2 and MUC5AC, as well as MUC5B and MUC6, in molecular subtypes of colorectal cancer. Seven-hundred and twenty-two incident colorectal carcinomas occurring in 702 participants of the Melbourne Collaborative Cohort Study were characterized for methylator status, MLH1 methylation, somatic BRAF and KRAS mutations, microsatellite-instability status, MLH1, MSH2, MSH6, and PMS2 mismatch repair, and p53 protein expression, and their histopathology was reviewed. Protein expression levels of MUC2, MUC5AC, MUC5B, MUC6, and the putative mucin regulator CDX2 were compared with molecular and clinicopathological features of colorectal cancers using odds ratios and corresponding 95% confidence intervals. MUC2 overexpression (>25% positive tumor cells) was observed in 33% colorectal cancers, MUC5B expression in 53%, and de novo MUC5AC and MUC6 expression in 50% and 39%, respectively. Co-expression of two or more of the mucins was commonly observed. Expression of MUC2, MUC5AC and MUC6 was strongly associated with features associated with tumorigenesis via the serrated neoplasia pathway, including methylator positivity, somatic BRAF p.V600E mutation, and mismatch repair deficiency, as well as proximal location, poor differentiation, lymphocytic response, and increased T stage (all P<0.001). Overexpression was observed in tumors with and without mucinous differentiation. There were inverse associations between expression of all four mucins and p53 overexpression. CDX2 expression was inversely associated with MUC2, MUC5AC and MUC6 expression. Our results suggest that, in methylator-positive tumors, mucin genes on chromosome 11p15.5 region undergo increased expression via mechanisms other than direct regulation by CDX2.
Serrated polyposis has only recently been accepted as a condition which carries an increased personal and familial risk of colorectal cancer. Described over four decades ago, it remains one of the ...most underrecognized and poorly understood of all the intestinal polyposes. With a variety of phenotypic presentations, it is likely that serrated polyposis represents a group of diseases rather than a single entity. Further, neoplastic progression in serrated polyposis may be associated with premature aging in the normal mucosa, typified by widespread gene promoter hypermethylation. From this epigenetically altered field, arise diverse polyps and cancers which show a range of molecular features. Despite a high serrated polyp count, only one-third of colorectal cancers demonstrate a BRAF V600E mutation, the molecular hallmark of the canonical serrated pathway, suggesting that though multiple serrated polyps act as a marker of an abnormal mucosa, the majority of CRC in these patients arise within lesions other than BRAF-mutated serrated polyps.
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