Diagnosis and treatment of colorectal tumors: Differences between Japan and the West and future prospects

Dye‐based chromoendoscopy has long been used routinely for endoscopic diagnosis of gastrointestinal tumors including colorectal tumors in Japan. In the West, on the other hand, dye‐based chromoendoscopy was not so commonly used. However, with the development of narrow band imaging (NBI), image‐enhanced endoscopy diagnosis has rapidly increased in the West.

The most critical difference between Japan and the West is the histopathological evaluation of the lesions, which determines a major cause of differences in diagnostic and treatment strategies. In the West, intramucosal adenocarcinoma is not diagnosed until the cancer has invaded submucosal layer. In Japan, on the other hand, cancer is mainly diagnosed based on nuclear and structural atypia, and thus intramucosal adenocarcinoma is diagnosed in lesions that correspond to high‐grade adenoma in the West.

In the West, since intramucosal carcinoma is not diagnosed by pathology, all benign adenomas are treated by piecemeal endoscopic resection, and only cancer invading the superficial submucosal layer is indicated for endoscopic submucosal dissection (ESD). Because of the risk of lymph node metastasis in the deep submucosal invasion, the European Society of Gastrointestinal Endoscopy and American Society for Gastrointestinal Endoscopy guidelines state that only superficial submucosal cancer is an indication for ESD. Unfortunately, it is impossible to selectively extract only superficial submucosal invasive cancer even with the use of magnified NBI and pit pattern observation. Therefore, we think that pathologists need to diagnose intramucosal adenocarcinoma with the potential to invade the submucosal layer based on the nuclear and structural atypia. Consequently, intramucosal adenocarcinoma and superficial submucosal cancers should be considered for en‐bloc ESD.

Prediction of tissue origin of adenocarcinomas in the esophagogastric junction by DNA methylation

BACKGROUND

Prediction of tissue origin of esophagogastric junction (EGJ) adenocarcinomas can be important for therapeutic decision, but no molecular marker is available. Here, we aimed to develop such a marker taking advantage of tissue-specific profiles of DNA methylation.

METHODS

DNA methylation profiles of gastric adenocarcinomas (GACs) were obtained by an Infinium HumanMethylation450 BeadChip array, and those of esophageal adenocarcinoma (EACs) were obtained from the TCGA database. DNA from formalin-fixed paraffin-embedded (FFPE) samples was analyzed by bisulfite pyrosequencing.

RESULTS

In the screening set, 51 of 145,841 CpG sites in CpG islands were methylated at significantly higher levels in 30 GACs compared to those in 30 EACs. Among them, SLC46A3 and cg09177106 were unmethylated in all the 30 EACs. Predictive powers of these two markers were successfully confirmed in an independent validation set (18 GACs and 18 EACs) (SLC46A3, sensitivity = 77.8%, specificity = 100%; cg09177106, sensitivity = 83.3%, specificity = 94.4%), and could be applied to FFPE samples (37 GACs and 18 EACs) (SLC46A3, P = 0.0001; cg09177106, P = 0.0028). On the other hand, EAC-specific markers informative in the FFPE samples could not be isolated. Using these GAC-specific markers, nine of 46 (19.6%) TCGA EGJ adenocarcinomas were predicted to be GACs.

CONCLUSIONS

Two GAC-specific markers, SLC46A3 and cg09177106, had a high specificity for identifying the tissue origin of EGJ adenocarcinoma.

Randomized phase III study of etoposide plus cisplatin versus irinotecan plus cisplatin in advanced neuroendocrine carcinoma of the digestive system: A Japan Clinical Oncology Group study (JCOG1213)

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Background: Neuroendocrine carcinoma (NEC) arising in the digestive system is a rare and high-grade malignant tumor. Treatment guidelines for advanced NEC recommend platinum-based chemotherapy regimens. Etoposide plus cisplatin (EP) and irinotecan plus cisplatin (IP) are commonly used as community standard regimens for NEC. However, it is unknown which is more effective. This phase III study aimed to identify more effective regimen between EP and IP in terms of overall survival (OS) for patients with advanced NEC. Methods: Eligibility criteria included chemotherapy-naïve patients with recurrent or unresectable, histologically confirmed NEC (WHO2010) arising from the gastrointestinal tract (GI), hepatobiliary and pancreas (HBP), ECOG PS of 0-1, age of 20–75 years. In the EP arm, etoposide (100 mg/m2 on days 1, 2 and 3) and cisplatin (80 mg/m2 on day 1) were administered every 3 weeks. In the IP arm, irinotecan (60 mg/m2 on days 1, 8 and 15) and cisplatin (60 mg/m2 on day 1) were repeated every 4 weeks. The primary endpoint was OS. Total of 140 patients (114 events) were required to detect a hazard ratio (HR) of 0.67 (median OS; 8/12 months in inferior/superior arms) with a two-sided alpha of 10% and power of 70%. Due to a rapid accrual, the sample size was increased to 170 (power of 80%). Pathology was centrally reviewed after the start of treatment. Results: Of all enrolled 170 patients (GI: 100, HBP: 70) from Aug 2014 to March 2020, median OS was 12.5 months in EP and 10.9 months in IP (HR 1.043 [a ratio of EP to IP], 90% CI, 0.794-1.370, p= 0.797). Median progression-free survival (PFS) was 5.6 months in EP and 5.1 months in IP (HR 1.060, 95% CI, 0.777-1.445). Response rate (RR) was 54.5% (42/77) in EP and 52.5% (42/80) in IP among patients with target lesions. No interactions with OS, PFS, or RR were seen in pre-planned subgroup analyses including primary organs or pathological findings. The common Grade 3-4 AEs (EP/IP) was neutropenia (91.5%/53.7%), leukocytopenia (61.0%/30.5%), and febrile neutropenia (26.8%/12.2%). Conclusions: A superiority was not demonstrated, which indicates that both EP and IP remain standard first-line chemotherapy. Clinical trial information: UMIN000014795.

Correlation of combined positive score of PD-L1 expression and clinical efficacy for advanced esophageal squamous cell carcinoma treated with nivolumab monotherapy

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Background: Based on the results of the ATTRACTION-3 trial, nivolumab has shown superiority compared to taxane monotherapy as second-line treatment for advanced esophageal squamous cell carcinoma (ESCC) patients (pts). However, the PD-L1 expression by tumor proportion score (TPS) did not obviously correlate to the efficacy. In contrast, PD-L1 expression by combined positive score (CPS) was used as a companion diagnosis for pembrolizumab in ESCC. There are little data on CPS with nivolumab in ESCC. Methods: We retrospectively reviewed the medical records of the pts with ESCC who received nivolumab monotherapy in our hospital. The CPS before nivolumab was evaluated by 22C3 antibody. We evaluated the correlation of CPS and clinical efficacy of progression-free survival (PFS), overall response rate (ORR), disease control rate (DCR) by using Cox proportional regression model and Fisher’s exact test. Results: Eighty-seven pts were selected for this analysis with a median follow-up time of 7.9 (1.2-84.1) months. Thirty pts (34.5%) had CPS < 10, and 57 patients (65.5%) had CPS≥10. Between two groups, the characteristics were as follows; median age (range): 62 (35-85) and 66 (46-85) years, PS 0: 20.0/36.8%, prior taxane: 50.0/40.4%, prior radiotherapy: 86.7/77.2%, respectively. The median PFS (95%CI) were 1.8 (1.2-2.8)/2.6 (1.8-33.8) months (HR: 0.85 [0.52-1.38], p = 0.50). The ORR/DCR were 21.1/31.6% in CPS < 10 group, and 22.2/57.8% in CPS≥10 group, and there was no statistical significance, respectively (p = 1.0/0.10). In multivariate analysis, only higher age was the favorite factor for PFS. From the result with another cut-off level of CPS, the proportion of CPS≥1/CPS≥20 was 90.8/36.8%. The HR of multivariate analysis with CPS≥1/CPS≥20 was 1.24/0.73, respectively. Conclusions: There was a trend toward better PFS with a higher cut-off point of CPS. CPS had the potential to be a biomarker even for nivolumab for advanced ESCC pts.

Endoscopic features of isolated and traditional serrated adenoma-associated superficially serrated adenomas of the colorectum

BACKGROUND AND AIM

Superficially serrated adenoma (SuSA) is a recently proposed subtype of colorectal serrated lesions. It is characterized by distinct clinicopathological and molecular features, including mixed serrated and adenomatous histology and frequent genetic alterations involving KRAS and RSPO. This study aimed to characterize the endoscopic features of isolated and traditional serrated adenoma (TSA)-associated SuSAs.

METHODS

We retrospectively evaluated the endoscopic findings of 25 isolated SuSAs and 21 TSA-associated SuSAs that were histologically and molecularly characterized.

RESULTS

SuSAs appeared as a sessile polyp or slightly elevated lesion located mostly in the sigmoid colon and rectum (88%). The size was between 3 and 20 mm (median, 6 mm). Most of them exhibited KRAS mutations (96%) and RSPO fusions/overexpression (92%). Endoscopically, many lesions had a whitish color (84%), a distinct border (96%), an irregular border (76%), and a lobulated surface (72%). However, diminutive lesions exhibited overlapping features with hyperplastic polyps. On narrow-band imaging, vessel patterns were invisible or appeared as lacy microvessels in most lesions (80%). Chromoendoscopy invariably showed stellar or elongated/branched stellar pits, indicating a serrated microarchitecture. Most TSA-associated SuSAs typically presented as polyps with a two-tier raised appearance, consisting of whitish lower and reddish higher components corresponding to a SuSA and a TSA, respectively.

CONCLUSIONS

SuSAs exhibit several characteristic endoscopic features on white-light and image-enhanced endoscopy. Diminutive lesions exhibit endoscopic features overlapping with hyperplastic polyps. Nonetheless, the endoscopic diagnosis of larger and TSA-associated SuSAs may be feasible.

Comparable genetic alteration profiles between gastric cancers with current and past Helicobacter pylori infection

Gastric cancers can develop even after Helicobacter pylori (H. pylori) eradication in 0.2-2.9% cases per year. Since H. pylori is reported to directly activate or inactivate cancer-related pathways, molecular profiles of gastric cancers with current and past H. pylori infection may be different. Here, we aimed to analyze whether profiles of point mutation and gene amplification are different between the two groups. Current or past infection by H. pylori was determined by positive or negative amplification of H. pylori jhpr3 gene by PCR, and past infection was established by the presence of endoscopic atrophy. Among the 90 gastric cancers analyzed, 55 were with current infection, and 35 were with past infection. Target sequencing of 46 cancer-related genes revealed that 47 gastric cancers had 68 point mutations of 15 different genes, such as TP53 (36%), KRAS (4%), and PIK3CA (4%) and that gene amplification was present for ERBB2, KRAS, PIK3CA, and MET among the 26 genes assessed for copy number alterations. Gastric cancers with current and past infection had similar frequencies of TP53 mutations (38% and 31%, respectively; p = 0.652) and oncogene activation (20% and 29%, respectively; p = 0.444). Gastric cancers with current and past infection had comparable profiles of genetic alterations.

APC mutations are common in adenomas but infrequent in adenocarcinomas of the non-ampullary duodenum

BACKGROUND

Recent studies highlighted the clinicopathological heterogeneity of non-ampullary duodenal adenomas and adenocarcinomas, but the detailed process of the malignant transformation remains unclear.

METHODS

We analyzed 144 adenomas and 54 adenocarcinomas of the non-ampullary duodenum for immunohistochemical phenotypes, genetic alterations, and mismatch repair (MMR) status to probe their histogenetic relationship.

RESULTS

The median ages of patients with adenoma and adenocarcinoma were the same (66 years). Adenomas were histologically classified as intestinal-type adenoma (n = 124), pyloric gland adenoma (PGA, n = 10), gastric-type adenoma, not otherwise specified (n = 9), and foveolar-type adenoma (n = 1). Protein-truncating APC mutations were highly frequent in adenomas (85%), with the highest prevalence in intestinal-type adenomas (89%), but rare in adenocarcinomas (9%; P = 2.1 × 10^-23). Close associations between phenotypic marker expression and genetic alterations were observed in adenomas, but not in adenocarcinomas, excluding the common association between GNAS mutations and MUC5AC expression. MMR deficiency was more frequent in adenocarcinomas (20%) than in adenomas (1%; P = 2.6 × 10^-6). One MMR-deficient adenoma and three MMR-deficient adenocarcinomas occurred in patients with Lynch syndrome. Additionally, three other patients with an MMR-deficient adenocarcinoma fulfilled the revised Bethesda criteria.

CONCLUSION

The discrepant APC mutation frequency between adenomas and adenocarcinomas suggests that APC-mutated adenomas, which constitute the large majority of non-ampullary duodenal adenomas, are less prone to malignant transformation. Non-ampullary duodenal adenocarcinomas frequently exhibit MMR deficiency and should be subject to MMR testing to determine appropriate clinical management, including the identification of patients with Lynch syndrome.

Spontaneous Regression of Mismatch Repair-Deficient Colon Cancer: A Case Series

Spontaneous regression of cancer is a rare phenomenon, with 33 colorectal cancer cases reported between 1900 and 2020.^1-4 Spontaneous regression is defined as the partial or complete disappearance of a tumor without treatment.^1,3 Several factors may be involved in this process, including biopsy, mechanical stress, humoral factors, and infection.^1,5 However, no concrete evidence for the mechanistic insights has been indicated.

Pathological complete response at the para-aortic nodes as a possible surrogate endpoint in gastric cancer surgery with para-aortic node dissection after neoadjuvant chemotherapy

PURPOSE

Gastric cancer with para-aortic node (PAN) metastasis has a chance to be cured with multidisciplinary treatment of D2 and PAN dissection (PAND) following neoadjuvant chemotherapy (NAC), but its prognosis remains unsatisfactory. To establish a better multidisciplinary treatment, a better surrogate endpoint is needed. The present study focused on a pathological complete response at the PANs alone as a new surrogate endpoint and evaluated its prognostic value.

METHODS

The study examined patients who received radical gastrectomy with D2 and PAND after NAC for gastric cancer with PAN metastasis from 2004 to 2015. The study compared five methods of evaluating the response to NAC: RECIST, clinical disappearance of PANs (cPAN), histological response of the primary tumor defined by Japanese Classification of Gastric Carcinoma (JCGC histological criteria) and Becker's criteria, and pathological disappearance of PANs (pPAN). The efficacy of these methods was compared using the hazard ratio (HR) for death between responders and non-responders.

RESULTS

Thirty-two patients were analyzed. The respective HR and 5-year overall survival rates of responders and non-responders were 1.316 and 49.1% vs. 60.0% by RECIST, 1.106 and 52.9% vs. 52.5% by cPAN, 0.246 and 71.3% vs. 28.6% by JCGC histological criteria, 0.239 and 76.2% vs. 36.8% by Becker's criteria, and 0.074 and 81.0% vs. 0.0% by pPAN.

CONCLUSIONS

A pathological complete response at the PANs had the lowest HR and clearly differentiated the survival, suggesting it might be a good surrogate endpoint for identifying future candidates for NAC in multidisciplinary treatment for gastric cancer with PAN metastasis.

Treatment outcomes of endoscopic submucosal dissection and surgery for colorectal neoplasms in patients with ulcerative colitis

Objectives

This study aimed to clarify the validity and long‐term outcomes of colorectal endoscopic submucosal dissection (ESD) of visible lesions (≥20 mm) in patients with ulcerative colitis (UC) and investigate the incidence of undetected lesions in surgical specimens.

Methods

This single‐center retrospective study included 11 lesions from nine patients with UC who underwent ESD and 19 lesions from nine patients with UC who underwent colectomy between March 2001 and January 2019. We evaluated the endoscopic findings of scarring, atrophy, and loss of haustra in the ESD group, and we determined the lesion visibility in the colectomy group. We investigated the clinicopathological features of all lesions and examined the follow‐up evaluations in the ESD group.

Results

The en bloc and curative resection rates of ESDs were 91% and 82%, respectively. Endoscopic findings of scarring, atrophic colitis, and loss of haustra were observed in two (18%), seven (64%), and one (9%) lesions, respectively. The two lesions with scarring showed severe submucosal fibrosis. Mortality and recurrence were not observed during the median follow‐up of 25 months. Metachronous lesions ≥20 mm were detected in two patients, which were successfully treated with ESDs. In the colectomy specimens, 21% of the lesions were undetected, 67% had multiple neoplasms, and 33% had multiple invasive cancers.

Conclusions

ESD is feasible and valid for large visible lesions in patients with UC; however, for lesions with endoscopic findings of scarring, technical difficulties in endoscopic resection must be considered. In addition, intensive surveillance colonoscopy is necessary to detect undetected lesions.

Summarise the estabished knowledge on this subject

The number of patients with ulcerative colitis (UC) has increased.

Clinical guidelines recommend that endoscopic resection for endoscopically visible dysplasia rather than colectomy in patients with UC.

Although some studies on the treatment outcomes of endoscopic submucosal dissection (ESD) for patients with UC have been conducted, the sample size was small and almost all reported lesions were relatively small (i.e., <20 mm); thus, the available data are limited.

What are the significance and/or new findins of this study?

Good outcomes of ESD for visible lesions (>20 mm) in patients with ulcerative colitis were demonstrated.

Technical difficulties are highly possible in lesions with endoscopic findings of scarring.

The prevalence of undetected lesions (approximately 20%) was the same between high (2‐3) and low (0‐1) Mayo endoscopic subscore groups based on the surgical specimens.

SAA1 is upregulated in gastric cancer-associated fibroblasts possibly by its enhancer activation

Cancer-associated fibroblasts (CAFs) tend to have tumor-promoting capacity, and can provide therapeutic targets. Even without cancer cells, CAF phenotypes are stably maintained, and DNA methylation and H3K27me3 changes have been shown to be involved. Here, we searched for a potential therapeutic target in primary CAFs from gastric cancer and a mechanism for its dysregulation. Expression microarray using eight CAFs and seven non-CAFs (NCAFs) revealed that serum amyloid A1 (SAA1), which encodes an acute phase secreted protein, was second most upregulated in CAFs, following IGF2. Conditioned medium (CM) derived from SAA1-overexpressing NCAFs was shown to increase migration of gastric cancer cells compared with that from control NCAFs, and its tumor-promoting effect was comparable to that of CM from CAFs. In addition, increased migration of cancer cells by CM from CAFs was mostly canceled with CM from CAFs with SAA1 knockdown. Chromatin immunoprecipitation (ChIP)-quantitative PCR showed that CAFs had higher levels of H3K27ac, an active enhancer mark, in the promoter and the two far upstream regions of SAA1 than NCAFs. Also, BET bromodomain inhibitors, JQ1 and mivebresib, decreased SAA1 expression and tumor-promoting effects in CAFs, suggesting SAA1 upregulation by enhancer activation in CAFs. Our present data showed that SAA1 is a candidate therapeutic target from gastric CAFs and indicated that increased enhancer acetylation is important for its overexpression.

Comparison of model fit and discriminatory ability of the 8th edition of the tumor-node-metastasis classification and the 9th edition of the Japanese classification to identify stage III colorectal cancer

BACKGROUND

The most widely accepted staging system for colorectal cancer (CRC) is the tumor-node-metastasis (TNM) classification. In Japan, the Japanese Classification of Colorectal, Appendiceal, and Anal Carcinoma (JCCRC) system is used. The two systems differ mainly in relation to tumor deposits (TD) and metastasis in the regional lymph nodes along the main feeding arteries and lateral pelvic lymph nodes (N3). Here, we investigated the prognostic ability of the two systems for stage III CRC.

METHODS

We reviewed 696 consecutive patients who underwent curative resection of stage III CRC at the National Cancer Center Hospital between May 2007 and April 2014. We examined the clinicopathological features of CRC and predicted overall survival (OS) and relapse-free survival (RFS) according to the 8th TNM and 9th JCCRC systems. The systems were compared using Akaike's information criterion (AIC), Harrell's concordance index (C-index), and time-dependent receiver-operating characteristic (ROC) curves.

RESULTS

The 9th JCCRC system was more clinically effective according to AIC (OS, 1199 vs. 1206; RFS, 2047 vs. 2057), showed better discriminatory ability according to the C-index (OS, 0.65 vs. 0.62; RFS, 0.62 vs. 0.58), and its time-dependent ROC curve was superior compared with the 8th TNM system.

CONCLUSION

These results suggest that the 9th JCCRC system has superior discriminative ability to the 8th TNM system, because the 9th JCCRC accounts for the presence of TD and N3 disease, which were both significant predictors of poor prognosis. Reconsidering the clinical value of these two factors in the TNM system could improve its clinical significance.

Histopathological atlas of desmoplastic reaction characterization in colorectal cancer

Emergent scientific evidence indicates the central role of cancer-associated fibroblasts in determining whether the microenvironment of cancer works as friend or foe of the host; however, there is no unified histological evaluation framework of fibrotic stroma in colorectal cancers. Myxoid stroma and keloid-like collagen are site-specific histopathological features generated by cancer-associated fibroblasts, which appear exclusively in the tumor front during desmoplastic reaction. On the basis of these two stromal components, desmoplastic reaction is categorized into three patterns-immature, intermediate and mature-using hematoxylin and eosin staining. In January 2020, a prospective randomized clinical trial, JCOG1805, to elucidate the value of adjuvant chemotherapy in stage II colorectal cancer patients with pathological risk factors of recurrence was launched in Japan, in which intermediate/immature desmoplastic reaction is one of the four risk factors selected as inclusion criteria. This paper covers the diagnostic criteria for the desmoplastic reaction classification being used in the JCOG1805 study.

Endoscopic Resection Before Surgery Does Not Affect the Recurrence Rate in Patients With High-Risk T1 Colorectal Cancer

INTRODUCTION

Patients with high-risk T1 colorectal cancer (CRC) after endoscopic resection (ER) should undergo surgery in view of the risk of lymph node metastasis. Although additional surgery can potentially prevent recurrence, there is a paucity of data and longitudinal studies exploring this potential. Hence, this study aimed to evaluate the prolonged influence of ER before additional surgery on recurrence in T1 CRC.

METHODS

Between January 2004 and October 2015, 162 patients who underwent secondary surgery (SS) after ER ([ER + SS] group) and 392 consecutive patients with T1 CRC who underwent primary surgery at our institution were retrospectively analyzed. Recurrence was analyzed in these 2 groups. High-risk CRC patients were histologically defined according to the Japanese Society for Cancer of the Colon and Rectum guidelines (2016) for the treatment of CRC. Data were analyzed based on clinical and histological features, including lymph node metastasis, and the number of lymph nodes evaluated.

RESULTS

The recurrence rate was comparable between the ER + SS and primary surgery groups, with no significant difference (P = 0.625, log-rank test). There was no significant difference in the recurrence in patients receiving adjuvant chemotherapy in both groups (7.4% vs 10.4%, P = 0.27). The difference in the mean number of lymph nodes dissected between both groups was also not significant (24.3 vs 25.3, P = 0.43).

DISCUSSION

There was no significant difference in recurrence rates between patients undergoing ER before surgery and those undergoing primary surgery for high-risk T1 CRC. Hence, ER may be acceptable for high-risk T1 CRC.

Influence of degree of DNA degradation in formalin-fixed and paraffin-embedded tissue samples on accuracy of genome-wide DNA methylation analysis

Aim: Depending upon the degree of DNA degradation of formalin-fixed and paraffin-embedded tissue samples, accuracy of measurement by Infinium MethylationEPIC BeadChip assay (Illumina, CA, USA) was assessed. Materials & methods: DNA quality of six formalin-fixed and paraffin-embedded lung tissue samples with different formalin fixation periods was assessed by Illumina quality control, DNA copy number and DNA integrity number value. Infinium data from restored bisulfite treated DNA were compared with datum from a fresh-frozen sample. Results: The correlation coefficient decreased from 0.993 to 0.970 depending upon DNA degradation, even if the Illumina quality control was met. Exclusion of specific probes improved the correlation regardless of tissue. Conclusion: Poor DNA quality can be assessed as an amplifiable DNA copy number and DNA integrity number value. Probe filtering has the potential to improve assay accuracy.

Risk of Lymph Node Metastasis in Patients with the Superficial Spreading Type of Esophageal Squamous Cell Carcinoma

BACKGROUND

Little is known about the clinicopathological characteristics of superficial spreading-type esophageal carcinoma extending ≥5 cm along the long axis of the esophagus. This study was aimed at investigating the frequency of lymph node metastasis (LNM) in patients with superficial spreading-type esophageal carcinoma.

METHODS

We reviewed the data of 320 patients with superficial esophageal squamous cell carcinoma who had undergone esophagectomy with lymph node dissection at our hospital between 1986 and 2010. The incidence of LNM was compared between the spreading (≥5 cm) and nonspreading (< 5 cm) types.

RESULTS

The multivariate analysis revealed significant differences in the likelihood of LNM depending on the lymphovascular invasion, the infiltrative growth pattern (INF)-c, and the depth. There was no difference in the LNM frequency between nonspreading and spreading type in the patients with epithelium (EP)-lamina propria, muscularis mucosa (MM)-submucosa (SM)1 and SM2/3 lesions. The frequencies of LNMs (nonspreading-type vs. spreading-type tumors) in the patients with MM-SM1 lesions were 7/47 (14.9%) versus 4/25 (16%) and those in the patients with SM2/3 lesions were 22/58 (37.9%) versus 4/14 (28.9%), when the lesions did not have lymphovascular invasion and INF-c.

CONCLUSIONS

Endoscopic resection can be selected for -EP-SM1 lesions, regardless of whether the lesions are of the spreading type or nonspreading type.

Gastric cancer is highly prevalent in Lynch syndrome patients with atrophic gastritis

BACKGROUND

Although gastric cancer is one of the Lynch syndrome (LS)-related tumors, the clinicopathological features of gastric cancer in patients with LS remain uncertain. To investigate the incidence risk and clinicopathological features of gastric neoplasms in LS, we conducted a retrospective cohort study in Japanese LS patients.

METHODS

LS patients with pathogenic mismatch repair (MMR) gene variants were extracted from the LS registry of the National Cancer Center Hospital, Japan. Cumulative risks of gastric neoplasm, including dysplasia and cancer, were estimated using the Kaplan-Meier method. Gastric atrophy was evaluated endoscopically and/or histologically. Immunohistochemical staining for MMR proteins was performed for all available specimens.

RESULTS

Of 118 eligible patients, 26 patients were diagnosed with 58 gastric neoplasms. The cumulative incidence of gastric neoplasm was 41.0% (95% confidence interval, 26.9-55.0) at the age of 70. Of these, 13 (50%) patients developed synchronous and/or metachronous multiple gastric neoplasms. Among the 49 gastric neoplasms available for detailed pathological evaluation, all were associated with intestinal metaplasia. Immunohistochemically, 42 (86%) were MMR-deficient. The individuals with gastric atrophy had a significantly higher risk of developing gastric neoplasms compared with those without gastric atrophy (26 cases/54 individuals vs. 0 cases/53 individuals) (P = 0.026).

CONCLUSION

LS patients, particularly those with atrophic gastritis, are at high risk of gastric neoplasm and often develop multiple tumors. Endoscopic surveillance for gastric cancer is recommended for LS patients, especially those with atrophic gastritis.

NTRK fusion-positive colorectal cancer in Japanese population

ALK, ROS1 and NTRK fusions are involved in the tumorigenesis of various organs, including colorectal cancer. This study aims to clarify the prevalence of these fusions in colorectal cancer in the Japanese population. Immunohistochemical analysis of 1012 specimens of colorectal cancer revealed two NTRK-positive cases (0.2%) whereas no ALK- or ROS1-positive cases were identified. Reverse transcription polymerase chain reaction (RT-PCR) detected an LMNA-NTRK1 fusion in a case of adenosquamous carcinoma and a TPM3-NTRK1 fusion in a case of tubular adenocarcinoma. Both NTRK1 fusion-positive cases lacked activating mutations in KRAS and BRAF and were mismatch repair-deficient with loss of MLH1 and PMS2 expression and MLH1 promoter methylation. Our results show that receptor tyrosine kinase fusions are rare but present in colorectal cancers in Japanese patients, with a prevalence similar to that reported in other countries.

Re-expression of REG family and DUOXs genes in CRC organoids by co-culturing with CAFs

Organoids derived from epithelial tumors have recently been utilized as a preclinical model in basic and translational studies. This model is considered to represent the original tumor in terms of 3D structure, genetic and cellular heterogeneity, but not tumor microenvironment. In this study, we established organoids and paired cancer-associated fibroblasts (CAFs) from surgical specimens of colorectal carcinomas (CRCs), and evaluated gene expression profiles in organoids with and without co-culture with CAFs to assess interactions between tumor cells and CAFs in tumor tissues. We found that the expression levels of several genes, which are highly expressed in original CRC tissues, were downregulated in organoids but re-expressed in organoids by co-culturing with CAFs. They comprised immune response- and external stimulus-related genes, e.g., REG family and dual oxidases (DUOXs), which are known to have malignant functions, leading tumor cells to proliferative and/or anti-apoptotic states and drug resistant phenotypes. In addition, the degree of differential induction of REG1 and DUOX2 in the co-culture system varied depending on CAFs from each CRC case. In conclusion, the co-culture system of CRC organoids with paired CAFs was able to partially reproduce the tumor microenvironment.

Recurrence after ESD curative resection for early gastric cancer

BACKGROUND

Endoscopic submucosal dissection (ESD) is gaining ground as a minimally invasive treatment for early gastric cancer (EGC) that has a negligible risk of lymph node metastasis. According to the 5th edition of Japanese gastric cancer treatment guidelines, annual or biannual follow-up with endoscopy is recommended, but follow-up with abdominal ultrasonography or computed tomography (CT) for surveillance of metastases is not recommended after the eCuraA resection. However, we experienced a case of lymph node recurrence following ESD resulting in eCuraA.

CASE PRESENTATION

A 76-year-old female received ESD for EGC in a previous hospital 4 years ago. Pathological findings were tub1, 30 mm, T1a (M), UL0, Ly0, V0, pHM-, pVM- (eCuraA) according to the 15th edition of Japanese Classification of Gastric Carcinoma. Follow-up esophagogastroduodenoscopy revealed submucosal tumor, which was suspected as a swollen lymph node by CT and endoscopic ultrasound fine-needle aspiration revealed the recurrence of gastric cancer. We performed total gastrectomy with D2 lymph node dissection. Postoperative pathological examination revealed no local recurrent tumor at the ESD site in the stomach. Swollen lymph node was diagnosed as metastasis and lymph node metastasis was limited near the cardia.

CONCLUSION

This case provides valuable information about tumor with a minimum poorly differentiated adenocarcinoma component may develop lymph node metastasis even satisfying the guidelines criteria for curative resection.

Impact of DNA integrity on the success rate of tissue-based next-generation sequencing: Lessons from nationwide cancer genome screening project SCRUM-Japan GI-SCREEN

In the nationwide cancer genome screening project SCRUM-Japan GI-SCREEN, 2590 archival formalin-fixed paraffin-embedded (FFPE) tumor tissues from 19 institutions were analyzed with two tissue-based next-generation sequencing (NGS) panels at the Clinical Laboratory Improvement Amendments (CLIA)-certified College of American Pathologists (CAP)-accredited central laboratory. The Oncomine Cancer Research Panel (OCP; 143 genes) succeeded in producing validated results for only 68.3% of the samples (%OCP-success). CE-IVD (25 genes) succeeded in 45.9% of the OCP-failed samples, leading to an overall NGS success (%combined-success) rate as high as 82.9%. Among 2573 samples, the DNA-integrity (ΔCt )-high (ΔCt  < 4.4, n = 1253) samples showed significantly higher %OCP- and %combined-success rates (90.2% and 97.4%, respectively) than the DNA-integrity-intermediate (4.4 < ΔCt  < 6.3, n = 911; 68.9% and 88.7%) and DNA-integrity-low ones (ΔCt  > 6.3 or polymerase chain reaction-failed, n = 409; 5.6% and 24.7%). Other factors associated with NGS success included the FFPE-sample storage period (<4 years), the specimen type (surgical) and the primary tumor site (colorectal). Multivariable analysis revealed DNA integrity as the factor with the strongest independent association with NGS success, although it was suggested that other institution-specific factors contribute to the discordance of inter-institutional NGS success rates. Our results emphasize the importance of DNA quality in FFPE samples for NGS tests and the impact of DNA integrity on quality monitoring of pathology specimens for achieving successful NGS.

Case report: potential treatment of metastatic amphicrine carcinoma of the rectum with FOLFOXIRI chemotherapy

Amphicrine carcinoma (AmC) is a unique epithelial tumor displaying exocrine and endocrine features in the same cell. It shows an adenocarcinoma-like cellular form and has endocrine granules. There are few reports describing chemotherapy for AmC. Here, we describe a case with metastatic AmC from the rectum that was treated with FOLFOXIRI chemotherapy.

A 64-year-old man was diagnosed with a submucosal lesion on the scar produced after an endoscopic mucosal resection, which had been performed for adenocarcinoma of the rectum 2 years before. The endoscopic submucosal dissection revealed AmC. The abdominoperineal resection including lymph nodes dissection was performed. Thereafter, computed tomography showed multiple liver metastases, and FOLFOXIRI was administered. The best overall response was partial response, and progression-free survival was 8.7 months. After 16.0 months since first-line chemotherapy the patient died. We can therefore conclude that FOLFOXIRI may be effective for AmC of the rectum.