RNF43 is an E3 ligase that suppresses the Wnt/β-catenin signaling pathway and is frequently mutated in microsatellite-unstable colorectal carcinoma. To investigate the pathogenetic role of RNF43 in the serrated pathway, we conducted mutation analysis of RNF43 in several types of colorectal neoplasms. RNF43 mutation was found in 2 of 20 (10%) sessile serrated adenomas, 10 of 36 (28%) traditional serrated adenomas, 7 of 37 (19%) traditional serrated adenomas with cytologic dysplasia, and 9 of 31 (29%) BRAF-mutated/microsatellite-stable colorectal carcinomas; however, no mutation was found in 30 tubulovillous/villous adenomas. All mutations were located upstream of the ring finger domain of RNF43 without clustering, which is distinct from the pattern described for microsatellite-unstable colorectal carcinoma. RNF43 mutation was closely associated with BRAF mutation but inversely associated with KRAS mutation in traditional serrated adenoma with or without cytologic dysplasia (P=0.018 and 0.045, respectively). The finding of RNF43 mutation in sessile serrated adenoma and traditional serrated adenoma, but not in tubulovillous/villous adenoma, indicated that RNF43 mutation is an early and specific molecular aberration in the serrated pathway. The frequency of RNF43 mutation was significantly higher in traditional serrated adenoma with or without cytologic dysplasia and BRAF-mutated/microsatellite-stable colorectal carcinoma than sessile serrated adenoma. The unique molecular spectrum of these tumors suggests a stepwise neoplastic progression from sessile serrated adenoma to traditional serrated adenoma and BRAF-mutated/microsatellite-stable colorectal carcinoma, which should be recognized as the traditional serrated pathway to distinguish from the sessile serrated pathway.

Annexin A10 (ANXA10) is a member of the ANX family that is normally expressed in gastric mucosa. ANXA10 was recently observed to be upregulated in sessile serrated adenoma, a precursor to microsatellite-unstable colorectal cancer. We investigated the use of ANXA10 in diagnosing colorectal carcinoma. In an immunohistochemical analysis, the intensity and quantity of ANXA10, MUC5AC, MUC6 and CDX2 in 123 colorectal carcinomas were graded. We determined the molecular status of BRAF and KRAS mutations, as well as the microsatellite instability status and the CpG island methylator phenotype in all colorectal carcinomas, and subcategorized into four molecular subgroups according to the molecular derangements. Nuclear ANXA10 staining was present in 36 colorectal carcinomas, exhibiting a strong significant association with the BRAF mutation status (Po0.0001) and positive CpG island methylator phenotype (Po0.0001), and a borderline significant association with high levels of microsatellite instability (P ¼ 0.072). The ANXA10-positive colorectal carcinomas were frequently positive for MUC5AC and MUC6, and were associated with absent or reduced CDX2 expression (all Po0.0001). According to a classification and regression tree analysis, ANXA10 is a superior marker for the molecular subtyping of colorectal carcinomas and represents a specific marker for colorectal cancers of the serrated pathway. Our results indicated that ANXA10 expression is implicated in gastric programming in serrated-pathway-associated colorectal carcinoma. ANXA10-positive colorectal carcinoma is highly associated with the molecular features of the serrated neoplasia pathway.

Aims The aims of this study were to identify the genetic features of appendiceal epithelial neoplasms and correlate the genetic features with morphology. Methods and results We analysed the genetic features of a series of 47 appendiceal epithelial neoplasms of various morphologies by using targeted next‐generation sequencing of 11 genes commonly mutated in gastrointestinal neoplasms. Seven of nine serrated polyps harboured BRAF mutations, which are rare in other types of appendiceal tumours. Most cases of low‐grade appendiceal mucinous neoplasms (LAMNs) exhibited GNAS and KRAS mutations. LAMNs with a coexisting serrated polyp were all KRAS mutated. Four LAMNs with mutations in the Wnt/β‐catenin pathway, either through inactivating mutations in APC or RNF43 or activating mutations in CTNNB1, had focal proliferation of mucin‐poor low‐grade tumour cells, reminiscent of colorectal adenomas. Mutations in the Wnt/β‐catenin pathway were also identified in high‐grade appendiceal mucinous neoplasms, suggesting that Wnt/β‐catenin pathway activation is the driving force for the progression of LAMN to a higher‐grade lesion. Adenomatous polyps of the appendix frequently had APC, KRAS and TP53 mutations and were morphologically and molecularly similar to adenomatous polyps of the colorectum. Conclusions Our results indicate a close association between morphology and genetic events in appendiceal neoplasms and suggest a phylogenetic relationship between different entities.

The prognostic implication of BRAF mutant colorectal cancer remains paradoxical. Records of BRAF mutant and wild-type colorectal cancer patients at all stages were reviewed. Clinicopathologic features, including microsatellite instability, CpG islands methylator phenotype, and overall survival, of these patients were analyzed. Between 2005 and 2013, 428 colorectal cancer patients were enrolled in this study. The overall survival between BRAF mutant and wild-type patients with early-stage (stages I and II) colorectal cancer differed nonsignificantly (P = 0.99). By contrast, in late-stage (stages III and IV) patients, the median overall survival of BRAF mutant patients (N = 25) was significantly poorer than that of BRAF wild-type (N = 207) patients (BRAF mutant: 21.3 months (95% confidence interval [CI] 7.1-35.5); BRAF wild-type: 53.5 months (95% CI 37.5-69.5), P < 0.0001). In early-stage patients, we found that BRAF mutation was significantly associated with CpG island methylator phenotype-positive (P < 0.001), and microsatellite instability-high status (P = 0.0013). Conversely, in late-stage patients, BRAF mutation was significantly associated with CpG island methylator phenotype-positive (P = 0.0015) and the right-side colon (P = 0.014). BRAF mutation may have different prognostic implications in early- and late-stage colorectal cancer.

To identify better regimens in currently available chemotherapy would be beneficial to KRAS mutant metastatic colorectal cancer (mCRC) patients because they have fewer treatment options than KRAS wild-type mCRC patients. Clinicopathologic features and overall survival (OS) of KRAS mutant and wild-type mCRC patients who had used oxaliplatin-based, irinotecan-based, bevacizumab-based, as well as cetuximab-based regimens were compared to those who had never-used oxaliplatin-based, irinotecan-based, bevacizumab-based, as well as cetuximab-based regimens respectively. Between 2007 and 2012, a total of 394 mCRC patients, in whom 169 KRAS mutant and 225 KRAS wild-type, were enrolled. In KRAS mutant patients who had used oxaliplatin-based regimens (N = 131), the OS was significantly longer than that in KRAS mutant patients who had never-used oxaliplatin-based regimens (N = 38). The OS was 28.8 months [95% confidence interval (CI): 23.2–34.4] in KRAS mutant patients who had used oxaliplatin-based regimens versus 17.8 months [95% CI: 6.5–29.1] in KRAS mutant patients who had never-used oxaliplatin-based regimens (P = 0.026). Notably, OS in KRAS wild-type mCRC patients who had used oxaliplatin-based regimens (N = 185) was not significantly longer than that in KRAS wild-type mCRC patients who had never-used oxaliplatin-based regimens (N = 40) (P = 0.25). Furthermore, the OS in KRAS mutant patients who had used either irinotecan-based, bevacizumab-based or cetuximab-based regimens was not significantly different than that in KRAS mutant patients who had never-used either irinotecan-based, bevacizumab-based or cetuximab-based regimens respectively. In multivariate analyses, patients who had used oxaliplatin-based regimens remains an independent prognostic factor for longer OS in KRAS mutant mCRC patients. In conclusion, oxaliplatin-based regimens are more beneficial in KRAS mutant than in KRAS wild-type mCRC patients.