Clinicopathological characteristics of cancer associated with Crohn's disease

Machine learning‑based radiomics models accurately predict Crohn's disease‑related anorectal cancer

The radiological diagnosis of Crohn's disease (CD)-related anorectal cancer is difficult; it is often found in advanced stages and has a poor prognosis because of the difficulty of curative surgery. However, there are no studies on predicting the diagnosis of CD-related cancer. The present study aimed to develop a predictive model to diagnose CD cancerous lesions more accurately in a way that can be interpreted by clinicians. Patients with CD who developed anorectal CD lesions at Hyogo Medical University (Nishinomiya, Japan) between March 2009 and June 2022 were included in the present study. T2-weighted and T1-weighted magnetic resonance (MR) images were utilized for our analysis. Images of anorectal lesions were segmented using open-source 3D Slicer software, and radiomic features were extracted using PyRadiomics. Six machine learning models were investigated and compared: i) Support vector machine; ii) naive Bayes; iii) random forest; iv) light gradient boosting machine; v) extremely randomized trees; vi) and regularized greedy forest (RGF). SHapley Additive exPlanations (SHAP) values were calculated to assess the extent to which each radiomic feature contributed to the model's predictions compared to baseline, represented as the average of the model's predictions for all test data. The T2-weighted images of 28 patients with anorectal cancer and 40 non-cancer patients were analyzed and the contrast-enhanced T1-weighted images of 22 cancer and 40 non-cancer patients. The model with the highest area under the curve (AUC) was the RGF-based model constructed using T2-weighted image features, achieving an AUC of 0.944 (accuracy, 0.862; recall, 0.830). The SHAP-based model explanation suggested a strong association between the diagnosis of CD-related anorectal cancer and features such as complex lesion texture; greater pixel separation within the same coronal cross-section; larger, randomly distributed clumps of pixels with the same signal intensity; and a more spherical lesion shape on T2-weighted images. The MRI radiomics-based RGF model demonstrated outstanding performance in predicting CD-related anorectal cancer. These results may affect the diagnosis and surveillance strategies of CD-related colorectal cancer.

Possible poor prognosis in younger-onset Crohn's disease-associated anorectal cancer: A subanalysis of the Nationwide Japanese study

Background and aims

Crohn's disease (CD)-associated intestinal cancers are characterized by their high incidence, particularly at the anorectal site in the Japanese population. Accumulating evidence revealed that younger-onset sporadic colorectal cancer may exhibit unique biological features. To the best of our knowledge, few previous articles reported clinicopathological features in patients with CD-associated anorectal cancer (CDAAC). Therefore, we aimed to clarify the relationship between the younger onset of cancer and clinicopathological characteristics and prognosis, and the efficacy of cancer surveillance in patients with CDAAC.

Methods

CD patients who had been diagnosed with intestinal cancers from 1983 to 2020 were collected from 39 Japanese institutions in this study. Of 316 patients with CD-associated intestinal cancers, we analyzed 211 patients with CDAAC. We divided the patients into two groups according to the median age at cancer diagnosis (45 years old).

Results

Younger-onset CDAAC (YO-CDAAC) patients were significantly more likely to have a poor outcome than those with older-onset CDAAC (OO-CDAAC) in terms of both disease-free survival (DFS) (p = 0.0014) and overall survival (OS) (p = 0.023). Multivariate analysis showed that age under 45 years old at diagnosis of cancer was one of the independent factors for poor DFS and OS (hazard ratios: 2.15, 95% confidence interval: 1.09-4.26, p = 0.028, hazard ratios: 1.95, 95% confidence interval: 1.05-3.60, p = 0.033, respectively). Patients detected via surveillance showed significantly better DFS and OS rates than symptomatic patients in YO-CDAAC (p = 0.012 and 0.0031, respectively).

Conclusions

YO-CDAAC may have a poorer prognosis compared with OO-CDAAC. Surveillance could be important to improve cancer prognosis, especially in young CD patients with anorectal disease.

Quantifying 18F-Fluorodeoxyglucose Uptake in Perianal Fistulas on PET/CT: A Retrospective Analysis

RATIONALE AND OBJECTIVES

The use of 18F-fluorodeoxyglucose positron emission tomography-computed tomography (FDG-PET/CT) in assessing inflammatory diseases has shown significant promise. Uptake patterns in perianal fistulas, which may be an incidental finding on PET/CT, have not been purposefully studied. Our aim was to compare FDG uptake of perianal fistulas to that of the liver and anal canal in patients who underwent PET/CT for hematologic/oncologic diagnosis or staging.

MATERIALS AND METHODS

We retrospectively identified patients who underwent FDG-PET/CT imaging between January 2011 and May 2023, where the report described a perianal fistula or abscess. PET/CTs of patients included in the study were retrospectively analyzed to record the maximum standardized uptake value (SUVmax) of the fistula, abscess, anal canal, rectum, and liver. Fistula-to-liver and Fistula-to-anus SUVmax ratios were calculated. We statistically compared FDG activity among the fistula, liver, and anal canal. We also assessed FDG activity in patients with vs. without anorectal cancer, as well as across different St. James fistula grades.

RESULTS

The study included 24 patients with identifiable fistulas. Fistula SUVmax (mean=10.8 ± 5.28) was significantly higher than both the liver (mean=3.09 ± 0.584, p < 0.0001) and the anal canal (mean=5.98 ± 2.63, p = 0.0005). Abscess fistula SUVmax was 15.8 ± 4.91. St. James grade 1 fistulas had significantly lower SUVmax compared to grades 2 and 4 (p = 0.0224 and p = 0.0295, respectively). No significant differences existed in SUVmax ratios between anorectal and non-anorectal cancer groups.

CONCLUSION

Perianal fistulas have increased FDG avidity with fistula SUVmax values that are significantly higher than the anal canal.

Crohn's Disease-Associated Anorectal Cancer Has a Poor Prognosis With High Local Recurrence: A Subanalysis of the Nationwide Japanese Study

INTRODUCTION

Colorectal cancer (CRC) is one of the major life-threatening complications in patients with Crohn's disease (CD). Previous studies of CD-associated CRC (CD-CRC) have involved only small numbers of patients, and no large series have been reported from Asia. The aim of this study was to clarify the prognosis and clinicopathological features of CD-CRC compared with sporadic CRC.

METHODS

A large nationwide database was used to identify patients with CD-CRC (n = 233) and sporadic CRC (n = 129,783) over a 40-year period, from 1980 to 2020. Five-year overall survival (OS), recurrence-free survival (RFS), and clinicopathological characteristics were investigated. The prognosis of CD-CRC was further evaluated in groups divided by colon cancer and anorectal cancer (RC). Multivariable Cox regression analysis was used to adjust for confounding by unbalanced covariables.

RESULTS

Compared with sporadic cases, patients with CD-CRC were younger; more often had RC, multiple lesions, and mucinous adenocarcinoma; and had lower R0 resection rates. Five-year OS was worse for CD-CRC than for sporadic CRC (53.99% vs 71.17%, P < 0.001). Multivariable Cox regression analysis revealed that CD was associated with significantly poorer survival (hazard ratio 2.36, 95% confidence interval: 1.54-3.62, P < 0.0001). Evaluation by tumor location showed significantly worse 5-year OS and RFS of CD-RC compared with sporadic RC. Recurrence was identified in 39.57% of CD-RC cases and was mostly local.

DISCUSSION

Poor prognosis of CD-CRC is attributable primarily to RC and high local recurrence. Local control is indispensable to improving prognosis.

Clinical features and oncological outcomes of intestinal cancers associated with ulcerative colitis and Crohn's disease

BACKGROUND

Patients with longstanding inflammatory bowel disease are at high risk of developing intestinal cancers. In this study, we aimed to elucidate the differences between intestinal cancers associated with ulcerative colitis and Crohn's disease.

METHODS

Intestinal cancers in ulcerative colitis and Crohn's disease patients treated between 1983 and 2020 at 43 Japanese institutions were retrospectively analyzed..

RESULTS

A total of 1505 intestinal cancers in 1189 ulcerative colitis and 316 Crohn's disease patients were studied. Almost all of ulcerative colitis-associated cancers (99%) were in the colon and rectum, whereas half of Crohn's disease-associated cancers (44%) were in the anus, with 11% in the small intestine. Ulcerative colitis-associated cancers were diagnosed more frequently by surveillance (67% vs. 25%, P < 0.0001) and at earlier stages (stages 0-1, 71% vs. 27%, P < 0.0001) compared with Crohn's disease-associated cancers. Colorectal cancers associated with Crohn's disease showed a significantly worse 5-year overall survival rate than those associated with ulcerative colitis (stage 2, 76% vs. 89%, P = 0.01, stage 3, 18% vs. 68%, P = 0.0009, and stage 4, 0% vs. 13%, P = 0.04). Surveillance correlated with earlier diagnoses for ulcerative colitis- and Crohn's disease-associated intestinal cancers, whereas shorter intervals between endoscopic examinations correlated with an earlier cancer diagnosis in ulcerative colitis patients but not in Crohn's disease patients.

CONCLUSIONS

The clinical and oncological features of ulcerative colitis- and Crohn's disease-associated cancers were very different. Crohn's disease-associated cancers were diagnosed at more advanced stages and were detected less frequently by surveillance. Additionally, they showed a significantly poorer prognosis.

Postoperative results and complications of fecal diversion for anorectal Crohn's disease

PURPOSE

Fecal diversion is a less-invasive technique that can alleviate symptoms in patients with refractory anorectal Crohn's disease. However, complications, including recurrence of residual anorectal Crohn's disease, may develop. We aimed to evaluate the postoperative results and complications associated with fecal diversion in patients with refractory anorectal Crohn's disease.

METHODS

We enrolled 1218 Crohn's disease patients who underwent laparotomy at our institute. We retrospectively analyzed the clinical features of 174 patients who underwent fecal diversion for refractory anorectal Crohn's disease, complications of the diverted colorectum, and the incidence and risk factors for proctectomy after fecal diversion.

RESULTS

After fecal diversion, 74% of patients showed improved symptoms. However, bowel continuity restoration was successful in four patients (2.2%), and anorectal Crohn's disease recurred in all patients. Seventeen patients developed cancer with a poor prognosis. The rate of conversion to proctectomy after fecal diversion was 41.3%, and the risk factors included rectal involvement (p = 0.02), loop-type stoma (p < 0.01), and the absence of treatment with biologics after fecal diversion (p = 0.03).

CONCLUSION

Fecal diversion for refractory anorectal Crohn's disease can improve clinical symptoms. Patients with rectal involvement or loop-type stoma have a greater risk of requiring proctectomy following fecal diversion. The administration of biologic may decrease the rate of proctectomy.

Colorectal cancer in Crohn's disease: a series of 6 cases

Background

Colorectal cancer (CRC) is the most malignant complication in patients with Crohn’s disease (CD). We report 6 cases of CD-related CRC treated surgically at our hospital.

Case presentation

From 2010 to 2016, six CD patients were diagnosed with CRC. All patients were diagnosed with CD at < 25 years old, and the interval from onset of CD to diagnosis of CRC was > 10 years (range, 15–42 years) in all patients. The histological type of cancer was mucinous carcinoma in two cases, well-differentiated tubular adenocarcinoma in two cases, and moderately differentiated tubular adenocarcinoma in two cases. CRC was detected by screening colonoscopy in three cases (50%), and from clinical symptoms in the remaining three cases (50%). Two cases underwent colonoscopy within 2 months after symptom onset, detecting CRC in the relatively early stage. However, one case was diagnosed with advanced-stage CRC by endoscopy 1 year after symptom onset, and experienced poor prognosis.

Conclusions

Regular surveillance colonoscopy is needed to detect early-stage CRC in CD patients. Clear surveillance methods need to be established based on evidence.

Adverse Oncologic Outcomes of Adenocarcinoma of the Anal Canal in Patients With Crohn's Disease

BACKGROUND

Anal lesions in cases of Crohn's disease can give rise to adenocarcinoma of the anal canal; however, the oncologic outcomes in these patients have not yet been thoroughly investigated.

OBJECTIVE

This study aimed to clarify the influence of Crohn's disease on the oncologic outcomes in patients with adenocarcinoma of the anal canal.

DESIGN

This was a retrospective observational study from a prospectively collected database.

SETTINGS

The study was conducted at a single institution.

PATIENTS

This study included 102 patients with adenocarcinoma of the anal canal, including 34 (33.3%) with Crohn's disease-associated lesions and 68 (66.7%) with non-Crohn's disease-associated lesions.

MAIN OUTCOME MEASURES

Prognostic factors were detected using a Cox regression analysis, and the oncologic outcomes were calculated using the Kaplan-Meier method.

RESULTS

Crohn's disease-associated patients were significantly younger (45 vs 62 y; p < 0.001), had a high incidence of external/anal gland-type disease (61.8% vs 5.9%, p < 0.001) and had large tumors (7.1 ± 3.0 vs 4.7 ± 2.3 cm; p = 0.03) in comparison with non-Crohn's disease-associated patients. A Cox regression analysis showed that an advanced clinical T stage (T3 or T4; tumor size ≥5 cm) was an independent risk factor for 5-year local recurrence-free survival (HR = 3.49; p = 0.04), disease-free survival (HR = 2.82; p = 0.008), and overall survival (HR = 2.92; p = 0.006), and Crohn's disease association was an independent prognostic factor for local recurrence-free survival (HR = 2.29; p = 0.04) and overall survival (HR = 2.86; p = 0.04). The oncologic outcomes of patients who had the 2 abovementioned negative factors (cT3,4 Crohn's disease-associated patients) were significantly poorer than those of T3,4 non-Crohn's disease-associated patients (5-year local recurrence-free survival: 32.5% vs 70.4%, p = 0.001; disease-free survival: 15.9% vs 40.7%, p = 0.04; overall survival: 25.8% vs 71.0%, p = 0.007).

LIMITATIONS

This was a single-arm, retrospective study.

CONCLUSIONS

Significantly poorer oncologic outcomes were confirmed in Crohn's disease-associated patients with large tumors. Thus, it is important to perform careful surveillance of anal lesions in patients with Crohn's disease while taking these facts into consideration. See Video Abstract at http://links.lww.com/DCR/B449.

RESULTADOS ONCOLGICOS ADVERSOS DEL ADENOCARCINOMA DEL CANAL ANAL EN PACIENTES CON ENFERMEDAD DE CROHN

ANTECEDENTES:Las lesiones anales en casos de enfermedad de Crohn pueden dar lugar a un adenocarcinoma del canal anal; sin embargo, los resultados oncológicos en estos pacientes aún no se han investigado a fondo.OBJETIVOS:Este estudio tuvo como objetivo aclarar la influencia de la enfermedad de Crohn en los resultados oncológicos en pacientes con adenocarcinoma del canal anal.DISEÑO:Estudio observacional retrospectivo de una base de datos recopilada prospectivamente.ENTORNO CLINICO:El estudio se realizó en una sola institución.PACIENTES:Este estudio incluyó 102 pacientes con adenocarcinoma del canal anal, incluidos 34 (33,3%) con lesiones asociadas a la enfermedad de Crohn y 68 (66,7%) con lesiones no asociadas a la enfermedad de Crohn.PRINCIPALES MEDIDAS DE VOLARACION:Los factores pronósticos se detectaron mediante un análisis de regresión de Cox y los resultados oncológicos se calcularon utilizando el método de Kaplan-Meier.RESULTADOS:Los pacientes asociados a la enfermedad de Crohn eran significativamente más jóvenes (45 versus a 62 años, p <0,001), tenían una alta incidencia de enfermedad de tipo glandular externo/ anal (61,8% versus a 5,9%, p <0,001) y tumores grandes (7,1 ± 3,0 cm versus a 4,7 ± 2,3 cm, p = 0,03) en comparación con los pacientes no asociados a la enfermedad de Crohn. Un análisis de regresión de Cox mostró que un estadío clínico T avanzado (T3,4; tamaño del tumor ≥5 cm) era un factor de riesgo independiente para la supervivencia sin recidiva local (SLF) a 5 años (índice de riesgo [HR]: 3,49, p = 0,04), supervivencia libre de enfermedad (SSE) (HR: 2,82, p = 0,008) y supervivencia general (SG) (HR: 2,92, p = 0,006), y la enfermedad de Crohn asociada fue un factor pronóstico independiente para la SLF (HR: 2,29, p = 0,04) y SG (HR: 2,86, p = 0,04). Los resultados oncológicos de los pacientes que tenían los dos factores negativos mencionados anteriormente (pacientes asociados con la enfermedad de Crohn cT3,4) fueron significativamente peores que los de los pacientes no asociados con la enfermedad de Crohn con T3,4 (LFS a 5 años: 32,5% versus a 70,4 %, p = 0,001; SSE: 15,9% versus a 40,7%, p = 0,04; SG: 25,8% versus a 71,0%, p = 0,007).LIMITACIONES:Un estudio retrospectivo de un solo brazo.CONCLUSIONES:Se confirmaron resultados oncológicos significativamente peores en pacientes asociados con la enfermedad de Crohn con tumores grandes. Por lo tanto, es importante realizar una vigilancia cuidadosa de las lesiones anales en pacientes con enfermedad de Crohn. Consulte Video Resumen en http://links.lww.com/DCR/B449.

Intestinal cancer in patients with Crohn's disease: A systematic review and meta-analysis

BACKGROUND AND AIM

Although surveillance colonoscopy is recommended by several guidelines for Crohn's disease (CD), the evidence is insufficient to support the validity of this recommendation. Moreover, the efficacy of surveillance colonoscopy for anorectal cancer remains unclear. Therefore, we performed a systematic review of cancer in patients with CD before considering the proper surveillance methods.

METHODS

We conducted a systematic review and meta-analysis examining the incidence of intestinal cancer and a literature review to clarify the characteristic features of cancer in CD. We performed the systematic literature review of studies published up to May 2019.

RESULTS

Overall, 7344 patients were included in eight studies. The standardized incidence ratios (95% confidence intervals) of colorectal cancer (CRC) and small bowel cancer (SBC) were 2.08 (1.43-3.02) and 22.01 (9.10-53.25), respectively. The prevalence of CRC and SBC was 57/7344 (0.77%) and 17/7344 (0.23%), respectively, during a median follow-up of 12.55 years. Additionally, 54 studies reporting 208 anorectal cancer cases were identified. In patients with anorectal cancer, the prognosis for survival was 2.1 ± 2.3 years, and advanced cancer greater than stage T3 occurred in 46/74 patients (62.1%). Many more reports of anorectal cancer were published in Asia than in Western countries.

CONCLUSION

Although we were unable to state a recommendation for surveillance for SBC, we should perform cancer surveillance for CRC in patients with CD. However, the characteristics of cancer may differ according to geography or race. We must establish proper and effective surveillance methods that are independently suitable to detect these differences.

A rare cecal subepithelial tumor in a Crohn´s Disease patient

Appendiceal tumors comprise a variety of histologic types, including appendiceal mucinous neoplasms, which can be grouped as premalignant lesions, tumors of uncertain malignant potential, and malignant lesions. The appendiceal mucinous neoplasms are characterized by mucinous epithelial proliferation with extracellular mucin and pushing tumor margins, commonly an incidental finding during operative exploration. We report the case of a low-grade appendiceal mucinous neoplasm presenting as a subepithelial lesion in Crohn´s Disease patient. The diagnosis was not straightforward, and only surgical resection allowed an accurate diagnosis. Although Inflammatory Bowel Disease is a risk factor for the development of colorectal neoplasms, the absolute risk for appendiceal tumors is uncertain. The frequency of progression to malignancy remains to be determined.

Incidence, Risk Factors and Outcomes of Cancer of the Anal Transitional Zone in Patients with Ulcerative Colitis

BACKGROUND AND AIMS

Performing a mucosectomy with a hand-sewn ileal pouch-anal anastomosis [IPAA] for ulcerative colitis [UC] theoretically reduces the risk of carcinoma arising from the anal transitional zone [ATZ]. Although current guidelines suggest a stapled anastomosis due to the low incidence of cancer after pouch surgery in UC patients, only a few small series have addressed the oncological advantage of mucosectomy. Therefore, we aimed to investigate the incidence of ATZ/pouch cancer.

METHODS

A total of 1970 UC patients who underwent surgery between April 1987 and December 2018 were included. We retrospectively analysed the incidences of primary ATZ cancer in the original operative specimen and de novo ATZ/pouch cancer after surgery. Possible risk factors for primary ATZ cancer and the pouch survival rate were assessed.

RESULTS

Fourteen [6.4%] primary ATZ cancers developed in 220 UC-colorectal cancer [CRC] cases. Multiple (odds ratio [OR] = 8.79, 95% confidence interval [CI] 2.77-27.83, p < 0.01) and rectal [OR = 6.48, 95% CI 1.41-29.7, p = 0.01] cancers were identified as independent risk factors for primary ATZ cancer. Four of 1970 [0.2%] patients developed de novo ATZ/pouch cancer and dysplasia. The 10-year estimated cumulative pouch survival rate was not significantly different between stapled IPAA and hand-sewn IPAA cases [95.9% and 97.3%, p = 0.25].

CONCLUSION

The risk of de novo ATZ/pouch cancer and dysplasia was rare. The decision to perform a hand-sewn or a stapled IAA should be made on a case-by-case basis. However, the relatively high incidence of primary ATZ cancer in UC patients with CRC suggests that mucosectomy should be recommended for this patient group.

Efficacy of Preoperative Oral Antibiotic Prophylaxis for the Prevention of Surgical Site Infections in Patients With Crohn Disease: A Randomized Controlled Trial

OBJECTIVES

We investigated the efficacy of oral antimicrobial prophylaxis in patients undergoing surgery for Crohn disease.

BACKGROUND

Although oral antibiotic prophylaxis with mechanical bowel preparation has been recommended for colorectal surgery, the use of this approach remains somewhat controversial. Moreover, the efficacy of this approach for inflammatory bowel disease also remains unclear.

METHODS

This study was conducted as a randomized controlled trial at the Hyogo College of Medicine. The study protocols were registered with the University Hospital Medical Information Network Clinical Trials Registry (000013369). In this study, 335 patients with Crohn disease who were scheduled to undergo intestinal resection with an open approach were randomly assigned to either group A or group B. The patients in group A received both preoperative oral antibiotics and intravenous antimicrobial prophylaxis, and intravenous antimicrobial prophylaxis alone was given to the patients in group B. All patients underwent preoperative mechanical bowel preparation with sodium picosulfate hydrate. The primary endpoint of this study was the incidence of surgical site infection (SSI) according to an intention-to-treat analysis.

RESULTS

Although the incidences of overall and organ/space SSI were not significantly different, the incidence of incisional SSI was significantly lower in group A (12/163; 7.4%) than in group B (27/162; 16.6%) (P = 0.01). In the multivariate analysis, the absence of oral antibiotic prophylaxis was an independent risk factor for incisional SSI (odds ratio: 3.3; 95% confidence interval: 1.3-8.3; P = 0.01).

CONCLUSIONS

Combined oral and intravenous antimicrobial prophylaxis in patients with Crohn disease contributed to the prevention of SSI.

The Supercarbonate Apatite-MicroRNA Complex Inhibits Dextran Sodium Sulfate-Induced Colitis

The incidence of inflammatory bowel disease (IBD) is increasing. Nucleic acid-based medicine has potential as a next-generation treatment, but it is rarely successful with IBD. The aim of this study was to establish a microRNA-based therapy in an IBD model. For this purpose, we used microRNA-29 (miR-29) and a supercarbonate apatite (sCA) nanoparticle as a drug delivery system. Injection of sCA-miR-29a-3p or sCA-miR-29b-3p into mouse tail veins markedly prevented and restored inflammation because of dextran sulfate sodium (DSS)-induced colitis. RNA sequencing analysis revealed that miR-29a and miR-29b could inhibit the interferon-associated inflammatory cascade. Subcutaneous injection of sCA-miR-29b also potently inhibited inflammation, and it efficiently targeted CD11c+ dendritic cells (DCs) among various types of immune cells in the inflamed mucosa. RT-PCR analysis indicated that the miR-29 RNAs in CD11c+ DCs suppressed the production of interleukin-6 (IL-6), transforming growth factor β (TGF-β), and IL-23 subunits in DSS-treated mice. This may inhibit Th17 differentiation and subsequent activation, which is critical in IBD pathogenesis. In vivo experiments using a non-natural artificial microRNA sequence revealed that targeting of DCs in the inflamed colon is an exceptional feature of sCA. This study suggests that sCA-miR-29s may open a new avenue in nucleic acid-based medicine for IBD treatment.

Genomic characterization of colitis-associated colorectal cancer

BACKGROUND

Inflammatory bowel disease (IBD), which includes ulcerative colitis (UC) and Crohn's disease (CD), is a chronic, idiopathic, repeated inflammatory disease. Colorectal cancer (CRC) that develops in patients with IBD is known as colitis-associated colorectal cancer (CAC), but the underlying carcinogenic mechanism remains unclear. Genomic analysis of sporadic CRC has been well described based on next-generation sequencing (NGS) data. Using NGS, we compared all exons of 415 cancer-associated genes in patients in Japan and the USA who had CRC and found similar genomic alteration patterns among the two populations. However, genomic analysis of CAC has not been thoroughly investigated.

MAIN BODY

The molecular pathogenesis of CAC shares many features with sporadic CRC, but there are distinct variations in the time and frequency of some alterations. Gene alterations in CAC are gradually being elucidated using genomic sequencing analyses. Some studies have shown that gene alteration patterns differ between UC and CD. The carcinogenesis of CAC depends on unique environmental, genetic, and immunological factors.

CONCLUSIONS

In this review, we have discussed the differences in genomic alterations between sporadic CRC and CAC. NGS in patients with IBD has the potential to detect early CAC and to suggest therapeutic targets.

Genomic landscape of colitis-associated cancer indicates the impact of chronic inflammation and its stratification by mutations in the Wnt signaling

Inflammatory bowel disease (IBD) increases the risk of colorectal cancer, known as colitis-associated cancer (CAC). It is still unclear what driver mutations are caused by chronic inflammation and lead to CAC development. To get insight into this issue, we investigated somatic alterations in CAC. We performed exome sequencing of 22 fresh CACs and targeted sequencing of 43 genes on 90 archive specimens from Japanese CAC patients, of which 58 were ulcerative colitis (UC) and 32 were Crohn's disease (CD). Consistently with the previous reports, TP53 was commonly mutated (66%) whereas APC, KRAS and SMAD4 were mutated less frequently (16%, 11% and 11%, respectively). Mucinous CD-CACs in the anus, an Asian-specific subtype of CD-CAC, had less somatic mutations in our target genes. We also found that RNF43, a negative regulator of the Wnt signaling, was somatically mutated in a significant fraction of CACs (10 of 90; 11%). Two lines of evidence indicated that somatic mutations of RNF43 were related to chronic inflammation. First, somatic mutations of RNF43 were significantly associated with longer duration of IBD. Second, clinico-pathological features suggested many of the APC-mutated CACs were actually sporadic colorectal cancer whereas RNF43-mutated CACs did not have this tendency. RNA-Seq analysis showed that RNF43-mutated CACs had elevated expression of c-Myc and its target genes, suggesting that RNF43 is a bona fide driver of CAC development. This study provides evidence that somatic mutation of RNF43 is the driver genetic alteration that links chronic inflammation and cancer development in about 10% of CACs.