APC/PIK3CA mutations and ß-catenin status predict tankyrase inhibitor sensitivity of patient-derived colorectal cancer cells.

BACKGROUND: Aberrant WNT/ß-catenin signaling drives carcinogenesis. Tankyrases poly(ADP-ribosyl)ate and destabilize AXINs, ß-catenin repressors. Tankyrase inhibitors block WNT/ß-catenin signaling and colorectal cancer (CRC) growth. We previously reported that 'short' APC mutations, lacking all seven ß-catenin-binding 20-amino acid repeats (20-AARs), are potential predictive biomarkers for CRC cell sensitivity to tankyrase inhibitors. Meanwhile, 'Long' APC mutations, which possess more than one 20-AAR, do not predict inhibitor-resistant cells. Thus, additional biomarkers are needed to precisely predict the inhibitor sensitivity. METHODS: Using 47 CRC patient-derived cells (PDCs), we examined correlations between the sensitivity to tankyrase inhibitors (G007-LK and RK-582), driver mutations, and the expressions of signaling factors. NOD.CB17-Prkdcscid/J and BALB/c-nu/nu xenograft mice were treated with RK-582. RESULTS: Short APC mutant CRC cells exhibited high/intermediate sensitivities to tankyrase inhibitors in vitro and in vivo. Active ß-catenin levels correlated with inhibitor sensitivity in both short and long APC mutant PDCs. PIK3CA mutations, but not KRAS/BRAF mutations, were more frequent in inhibitor-resistant PDCs. Some wild-type APC PDCs showed inhibitor sensitivity in a ß-catenin-independent manner. CONCLUSIONS: APC/PIK3CA mutations and ß-catenin predict the sensitivity of APC-mutated CRC PDCs to tankyrase inhibitors. These observations may help inform the strategy of patient selection in future clinical trials of tankyrase inhibitors.

Long-term outcomes of additional surgery after endoscopic resection versus primary surgery for T1 colorectal cancer.

INTRODUCTION: There is considerable concern about whether endoscopic resection (ER) prior to additional surgery (AS) for T1 colorectal cancer (CRC) has oncologically potential adverse effects. Therefore, this study aimed to compare the long-term outcomes, including overall survival (OS), of patients treated with AS after ER versus primary surgery (PS) for T1 CRC using a propensity score-matched analysis from a large observational study. METHODS: This study investigated 6105 patients with T1 CRC treated with either ER or surgical resection between 2009 and 2016 at 27 high-volume Japanese institutions, with those undergoing surgery alone included in the PS group and those undergoing AS after ER included in the AS group. Propensity score matching was used for long-term outcomes of mortality and recurrence analysis. RESULTS: After propensity score matching, 1219 of 2438 patients were identified in each group. The 5-year OS rates in the AS and PS groups were 97.1% and 96.0%, respectively (hazard ratio: 0.72, 95% confidence interval [CI]: 0.49-1.08), indicating the non-inferiority of the AS group. Moreover, 32 patients (2.6%) in the AS group and 24 (2.0%) in the PS group had recurrences, with no significant difference between the two groups (odds ratio: 1.34, 95% CI: 0.76-2.40, p = 0.344). DISCUSSION: ER prior to AS for T1 CRC had no adverse effect on patients' long-term outcomes, including the 5-year OS rate. ER is a viable first-line treatment option for endoscopically resectable T1 CRC.

Treatment Decision for Locally Resected T1 Colorectal Carcinoma-Verification of the Japanese Guideline Criteria for Additional Surgery Based on Long-Term Clinical Outcomes.

INTRODUCTION: To verify the value of the pathological criteria for additional treatment in locally resected pT1 colorectal carcinoma (CRC) which have been used in the Japanese Society for Cancer of the Colon and Rectum (JSCCR) guidelines since 2009. METHODS: We enrolled 4,719 patients with pT1 CRC treated at 27 institutions between July 2009 and December 2016 (1,259 patients with local resection alone [group A], 1,508 patients with additional surgery after local resection [group B], and 1,952 patients with surgery alone [group C]). All 5 factors of the JSCCR guidelines (submucosal resection margin, tumor histologic grade, submucosal invasion depth, lymphovascular invasion, and tumor budding) for lymph node metastasis (LNM) had been diagnosed prospectively. RESULTS: Any of the risk factors were present in 3,801 patients. The LNM incidence was 10.3% (95% confidence interval 9.3-11.4) in group B/C patients with risk factors, whereas it was 1.8% (95% confidence interval 0.4-5.2) in those without risk factors ( P < 0.01). In group A, the incidence of recurrence was 3.4% in patients with risk factors, but it was only 0.1% in patients without risk factors ( P < 0.01). The disease-free survival rate of group A patients classified as risk positive was significantly worse than those of groups B and C patients. However, the 5-year disease-free survival rate in group A patients with no risk was 99.2%. DISCUSSION: Our large-scale real-world multicenter study demonstrated the validity of the JSCCR criteria for pT1 CRC after local resection, especially regarding favorable outcomes in patients with low risk of LNM.

Unique Biology of Pancreatic Ductal Adenocarcinoma Accompanied by Rapidly Impaired Diabetes: A Favorable Long-Term Survival Following Curative Resection.

BACKGROUND: Pancreatic ductal adenocarcinomas (PDACs) are sometimes diagnosed accompanied by rapidly impaired diabetes (PDAC-RID). Although this type of PDAC may have unusual biological features, these features have not been explained. METHODS: Patients with PDAC who underwent upfront pancreatectomy between 2010 and 2018 were retrospectively reviewed. PDAC-RID was defined as a glycated hemoglobin (HbA1c) value of ≥ 8.0% of newly diagnosed diabetes, and acute exacerbation of previously diagnosed diabetes. Other patients were classified as PDAC with stable glycometabolism (PDAC-SG). Clinicopathological factors, long-term survival rates, and recurrence patterns were evaluated. RESULTS: Of the 520 enrolled patients, 104 were classified as PDAC-RID and 416 as PDAC-SG. There was no significant difference regarding TNM staging, resectability, or adjuvant chemotherapy rate between the groups. However, 5-years cancer-specific survival (CSS) was significantly higher in the PDAC-RID group than in the PDAC-SG group (45.3% vs. 31.1%; p = 0.02). This survival difference was highlighted in relatively early-stage PDAC (≤ pT2N1) (CSS: 60.8% vs. 43.6%; p = 0.01), but the difference was not significant for advanced-stage PDAC. A multivariate analysis of early-stage PDAC showed that PDAC-SG was an independent risk factor of shorter CSS (hazard ratio 1.76; p = 0.02). The hematogenous metastatic rate in early-stage PDAC was lower in the PDAC-RID group than in the PDAC-SG group (18.3% vs. 35.8%; p = 0.01). CONCLUSIONS: PDAC-RID showed a favorable long-term survival rate after curative resection with low hematogenous metastases, which may be due to its unique biology.

Development and Validation Study of the Prognostic Impact of Deep Learning-Determined Myxoid Stroma After Neoadjuvant Chemotherapy in Patients with Esophageal Squamous Cell Carcinoma.

PURPOSE: This study was designed to investigate the prognostic significance of artificial intelligence (AI)-based quantification of myxoid stroma in patients undergoing esophageal squamous cell carcinoma (ESCC) surgery after neoadjuvant chemotherapy (NAC) and to verify its significance in an independent validation cohort from another hospital. METHODS: We evaluated two datasets of patients with pathological stage II or III ESCC who underwent surgery after NAC. Cohort 1 consisted of 85 patients who underwent R0 surgery for the primary tumor after NAC. Cohort 2, the validation cohort, consisted of 80 patients who received same treatments in another hospital. AI-based myxoid stroma was evaluated in resected specimens, and its area was categorized by using the receiver operating characteristic curve for overall survival (OS) of cohort 1. RESULTS: The F1 scores, which are the degree of agreement between the automatically detected myxoid stroma and manual annotations, were 0.83 and 0.79 for cohorts 1 and 2. The myxoid stroma-high group had a significantly poorer prognosis than the myxoid stroma-low group in terms of OS, disease-specific survival (DSS), and recurrence-free survival (RFS) in cohort 1. Comparable results were observed in cohort 2, where OS, DSS, and RFS were significantly affected by myxoid stroma. Multivariate analysis for RFS revealed that AI-determined myxoid stroma-high was one of the independent prognostic factors in cohort 1 (hazard ratio [HR] 1.97, p = 0.037) and cohort 2 (HR 4.45, p < 0.001). CONCLUSIONS: AI-determined myxoid stroma may be a novel and useful prognostic factor for patients with pathological stage II or III ESCC after NAC.

Early gastric cancer with RhoGAP fusion is linked to frequent nodal metastasis and a part of microtubular-mucocellular histology.

INTRODUCTION: Gastric cancer with fusion genes involving the Rho GTPase-activating protein domain (RhoGAP-GC) is mainly included in the genomically stable type of The Cancer Genome Atlas classification. Clinical implications and histological characteristics of RhoGAP-GC in the early phase remain unclear. METHODS: We analyzed 878 consecutive pT1b GCs for RhoGAP and its partner genes using fluorescence in situ hybridization assay. RESULTS: RhoGAP fusion was detected in 57 (6.5%) GCs. Univariate analysis revealed that female sex, middle-lower third tumor location, advanced macroscopic type, tumor diameter > 2 cm, pT1b2, lymphatic invasion, venous invasion, negative EBER-ISH, and RhoGAP fusion were significantly associated with lymph node metastasis (LNM). Multivariate analysis presented RhoGAP fusion, lymphatic invasion, tumor diameter > 2 cm, advanced macroscopic type, venous invasion, and middle-lower third tumor location as independent risk factors for LNM. Notably, RhoGAP fusion had the highest odds ratio (3.92) for LNM among analyzed parameters (95% CI 2.12-7.27; p < 0.001). Compared to non-RhoGAP-GCs, RhoGAP-GCs were significantly frequent in younger females and showed the highest incidence of lymphatic invasion (56.2%) and LNM (49.1%) (p < 0.001). Histologically, microtubular architecture with pseudo-trabecular interconnection and small aggregations of tumor cells with a varied amount of cytoplasmic mucin, named "microtubular-mucocellular (MTMC) histology," was found in 93.0% (53 of 57) of RhoGAP-GCs in the intramucosal area. MTMC histology showed high sensitivity and negative predictive value (93.0% and 99.4%, respectively) for RhoGAP fusion, albeit positive predictive value is low (34.9%). CONCLUSION: RhoGAP-GC is linked to a characteristic MTMC histology and a high incidence of LNM.

Long- vs short-segment Barrett's esophagus-derived adenocarcinoma: clinical features and outcomes of endoscopic submucosal dissection.

BACKGROUND: The incidence of Barrett's esophageal adenocarcinoma (BEA) is increasing, and endoscopic submucosal dissection (ESD) has been frequently performed for its treatment. However, the differences between the characteristics and ESD outcomes between short- and long-segment BEA (SSBEA and LSBEA, respectively) are unclear. We compared the clinicopathological characteristics and short- and long-term outcomes of ESD between both groups. METHODS: We retrospectively reviewed 155 superficial BEAs (106 SSBEAs and 49 LSBEAs) treated with ESD in 139 patients and examined their clinicopathological features and ESD outcomes. SSBEA and LSBEA were classified based on whether the maximum length of the background mucosa of BEA was < 3 cm or ≥ 3 cm, respectively. RESULTS: Compared with SSBEA, LSBEA showed significantly higher proportions of cases with the macroscopically flat type (36.7% vs. 5.7%, p < 0.001), left wall location (38.8% vs. 11.3%, p < 0.001), over half of the tumor circumference (20.4% vs. 1.9%, p < 0.001), and synchronous lesions (17.6% vs. 0%, p < 0.001). Compared with SSBEA, regarding ESD outcomes, LSBEA showed significantly longer resection duration (91.0 min vs. 60.5 min, p < 0.001); a lower proportion of submucosal invasion (14.3% vs. 29.2%, p = 0.047), horizontal margin negativity (79.6% vs. 94.3%, p = 0.0089), and R0 resection (69.4% vs. 86.8%, p = 0.024); and a higher proportion of post-procedural stenosis cases (10.9% vs. 1.9%, p = 0.027). The 5-year cumulative incidence of metachronous cancer in patients without additional treatment was significantly higher for LSBEA than for SSBEA (25.0% vs. 0%, p < 0.001). CONCLUSIONS: The clinicopathological features of LSBEA and SSBEA and their treatment outcomes differed in many aspects. As LSBEAs are difficult to diagnose and treat and show a high risk of metachronous cancer development, careful ESD and follow-up or eradication of the remaining BE may be required.

Prognostic factors for patients 85 years or older undergoing endoscopic submucosal dissection for early gastric cancer.

BACKGROUND: Little is known about prognostic factors for patients 85 years or older undergoing endoscopic submucosal dissection for early gastric cancer. Therefore, this study aimed to identify such prognostic factors. METHODS: We retrospectively evaluated the long-term outcomes and prognostic factors of 143 patients 85 years or older undergoing endoscopic submucosal dissection for early gastric cancer at a single-center between October 2005 and September 2020. Using the Kaplan-Meier method and a Cox proportional hazards regression model, we examined the relationships of patient characteristics and endoscopic curability (additional gastrectomy recommended [eCuraC-2] or not recommended) with overall survival. RESULTS: The median age of the patients was 86 years, and most patients were men (65%). The eCuraC-2 rate was 14.7%. During the follow-up period, 55 patients died; however, only two patients died due to gastric cancer. The 3-year and 5-year overall survival rates were 91.5% and 74.7%, respectively. Male sex (hazard ratio, 2.23; 95% confidence interval, 1.16-4.30), American Society of Anesthesiologists Physical Status of 3 (hazard ratio, 2.57; 95% confidence interval, 1.32-4.99), body mass index < 18.9 kg/m2 (hazard ratio, 2.21; 95% confidence interval, 1.11-4.40), and eCuraC-2 (hazard ratio, 3.04; 95% confidence interval, 1.37-6.75) were identified as independent prognostic factors. Moreover, patients with eCuraC-2 had significantly more poor prognostic factors than those who did not. CONCLUSIONS: The decision to perform endoscopic submucosal dissection for patients with the aforementioned prognostic factors should be carefully considered because follow-up without endoscopic submucosal dissection is possible.

Prognostic factors of para-aortic lymph node metastasis from colorectal cancer in highly selected patients undergoing para-aortic lymph node dissection.

PURPOSE: We investigated the surgical outcomes of para-aortic lymph node (PALN) dissection in patients with colorectal cancer and assessed the prognostic factors related to the survival. METHODS: This single-center retrospective study included 31 patients with synchronous or metachronous PALN metastasis from colorectal cancer who underwent PALN dissection between January 2006 and December 2018. RESULTS: Twenty-one patients had synchronous PALN metastasis, and 10 had metachronous PALN metastasis. Seven patients had either simultaneous distant metastasis or a history of distant metastasis other than PALN metastasis at the time of PALN dissection. Eighteen patients underwent adjuvant chemotherapy. The 5-year overall and recurrence-free survival rates were 54.2 and 17.2%, respectively. A multivariable analysis revealed that rectal cancer, metachronous PALN metastasis, and three or more pathological PALN metastases were significantly poor prognostic factors for the recurrence-free survival. Among patients with rectal cancer, lower rectal cancer and lateral pelvic lymph node metastasis were poor prognostic factors for the overall survival. CONCLUSION: Curative PALN dissection for PALN metastasis from colorectal cancer is feasible with favorable long-term outcomes. A multidisciplinary approach, including surgery and chemotherapy, is needed for colorectal cancer with PALN metastasis to improve the long-term outcomes.

Risk stratification for synchronous/metachronous recurrence after endoscopic submucosal dissection for Barrett's esophageal adenocarcinoma using the length of Barrett's esophagus.

BACKGROUND: In Japan, the standard management of Barrett's esophageal adenocarcinoma after endoscopic submucosal dissection involves follow-up; however, multifocal synchronous/metachronous lesions are sometimes observed after endoscopic submucosal dissection. Risk stratification of multifocal cancer facilitates appropriate treatment, including eradication of Barrett's esophagus in high-risk cases; however, no effective risk stratification methods have been established. Thus, we identified the risk factors for multifocal cancer and explored risk-stratified treatment strategies for residual Barrett's esophagus. METHODS: We retrospectively reviewed the data of 97 consecutive patients with superficial Barrett's esophageal adenocarcinomas who underwent curative resection with endoscopic submucosal dissection. Multifocal cancer was defined by the presence of synchronous/metachronous lesions during follow-up. We used Cox regression analysis to identify the risk factors for multifocal cancer and subsequently analyzed differences in cumulative incidences. RESULTS: The cumulative incidences of multifocal cancer at 1, 3, and 5 years were 4.4%, 8.6%, and 10.7%, respectively. Significant risk factors for multifocal cancer were increased circumferential and maximal lengths of Barrett's esophagus. The cumulative incidences of multifocal cancer at 3 years were lower for patients with circumferential length < 4 cm and maximal length < 5 cm (2.9% and 1.2%, respectively) than for patients with circumferential length ≥ 4 cm and maximal length ≥ 5 cm (51.5% and 49.1%, respectively). CONCLUSIONS: Risk stratification of multifocal cancer using length of Barrett's esophagus was effective. Further multicenter prospective studies are needed to substantiate our findings.

Risk Factors for Lymph Node Metastasis of Rectal Neuroendocrine Tumor and Its Prognostic Impact: A Single-Center Retrospective Analysis of 195 Cases with Radical Resection.

PURPOSE: The incidence of rectal neuroendocrine tumors (NETs) has been steadily increasing. The risk factors for and prognostic impact of lymph node (LN) metastasis were analyzed in 195 patients with stage I-III rectal NET who underwent radical surgery. METHODS: This retrospective, single-center study analyzed risk factors for LN metastasis focusing on previously identified factors and a novel risk factor: multiple rectal NETs. The association between LN metastasis and the prognosis was also analyzed. RESULTS: Pathologically, the LN metastasis rate (also the rate of stage III disease) was 39%, which was higher than the clinical LN metastasis rate of 14%. Tumor size > 10 mm, presence of central depression, tumor grade G2, depth of invasion, LN swelling on preoperative imaging (cN1), venous invasion and multiple NETs were identified as risk factors for LN metastasis. As the tumor size and risk factors increased, the rate of LN metastasis increased. Among these 7 factors, venous invasion, cN1, and multiple NETs were identified as independent predictors of LN metastasis. LN metastasis of rectal NETs was associated with significantly poor disease-free and disease-specific survival. CONCLUSIONS: As risk factors increase, the potential for rectal NETs to metastasize to the LNs increases and LN metastasis is associated with a poor prognosis. This is the first study to report multiple NETs as a risk factor for LN metastasis. A future study examining the survival benefit of radical surgery accompanying LN dissection compared with local resection is warranted.

Nomogram as a novel predictive tool for lymph node metastasis in T1 colorectal cancer treated with endoscopic resection: a nationwide, multicenter study.

BACKGROUND AND AIMS: Since 2009, the Japanese Society for Cancer of the Colon and Rectum guidelines have recommended that tumor budding and submucosal invasion depth, in addition to lymphovascular invasion and tumor grade, be included as risk factors for lymph node metastasis (LNM) in patients with T1 colorectal cancer (CRC). In this study, a novel nomogram was developed and validated by usirge-scale, real-world data, including the Japanese Society for Cancer of the Colon and Rectum risk factors, to accurately evaluate the risk of LNM in T1 CRC. METHODS: Data from 4673 patients with T1 CRC treated at 27 high-volume institutions between 2009 and 2016 were analyzed for LNM risk. To prepare a nonrandom split sample, the total cohort was divided into development and validation cohorts. Pathologic findings were extracted from the medical records of each participating institution. The discrimination ability was measured by using the concordance index, and the variability in each prediction was evaluated by using calibration curves. RESULTS: Six independent risk factors for LNM, including submucosal invasion depth and tumor budding, were identified in the development cohort and entered into a nomogram. The concordance index was .784 for the clinical calculator in the development cohort and .790 in the validation cohort. The calibration curve approached the 45-degree diagonal in the validation cohort. CONCLUSIONS: This is the first nomogram to include submucosal invasion depth and tumor budding for use in routine pathologic diagnosis based on data from a nationwide multi-institutional study. This nomogram, developed with real-world data, should improve decision-making for an appropriate treatment strategy for T1 CRC.

Genomic features of Helicobacter pylori-naïve diffuse-type gastric cancer.

Helicobacter pylori (HP) is a major etiologic driver of diffuse-type gastric cancer (DGC). However, improvements in hygiene have led to an increase in the prevalence of HP-naïve DGC; that is, DGC that occurs independent of HP. Although multiple genomic cohort studies for gastric cancer have been conducted, including studies for DGC, distinctive genomic differences between HP-exposed and HP-naïve DGC remain largely unknown. Here, we employed exome and RNA sequencing with immunohistochemical analyses to perform binary comparisons between 36 HP-exposed and 27 HP-naïve DGCs from sporadic, early-stage, and intramucosal or submucosal tumor samples. Among the samples, 33 HP-exposed and 17 HP-naïve samples had been preserved as fresh-frozen samples. HP infection status was determined using stringent criteria. HP-exposed DGCs exhibited an increased single nucleotide variant burden (HP-exposed DGCs; 1.97 [0.48-7.19] and HP-naïve DGCs; 1.09 [0.38-3.68] per megabase; p = 0.0003) and a higher prevalence of chromosome arm-level aneuploidies (p < 0.0001). CDH1 was mutated at similar frequencies in both groups, whereas the RHOA-ARHGAP pathway misregulation was exclusive to HP-exposed DGCs (p = 0.0167). HP-exposed DGCs showed gains in chromosome arms 8p/8q (p < 0.0001), 7p (p = 0.0035), and 7q (p = 0.0354), and losses in 16q (p = 0.0167). Immunohistochemical analyses revealed a higher expression of intestinal markers such as CD10 (p < 0.0001) and CDX2 (p = 0.0002) and a lower expression of the gastric marker, MUC5AC (p = 0.0305) among HP-exposed DGCs. HP-naïve DGCs, on the other hand, had a purely gastric marker phenotype. This work reveals that HP-naïve and HP-exposed DGCs develop along different molecular pathways, which provide a basis for early detection strategies in high incidence settings. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Clinicopathological study of surgically treated non-neoplastic diseases of the pancreas with special reference to autoimmune pancreatitis.

PURPOSE: After the popularization of serum immunoglobulin G4 (IgG4) measurement and endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) in our institute, surgical resection for non-neoplastic diseases of the pancreas became less common. Although the incidence of such false-positive cases was clarified in the 10-year period after the introduction of these measures (2009-2018), these data were not compared with the 30 years before 2009 (1979-2008). This study was performed to determine the percentage of autoimmune pancreatitis (AIP) that was included during the latter period and how the numbers of false-positive cases differed between the two periods. METHODS: From 1979 to 2008, 51 patients had clinical suspicion of pancreatic carcinoma (false-positive disease). Among these 51 patients, 32 non-alcoholic patients who had tumor-forming chronic pancreatitis (TFCP) were clinically, histologically, and immunohistochemically compared with 11 patients who had TFCP during the latter 10-year period. RESULTS: Retrospective IgG4 immunostaining of false-positive TFCP revealed 14 (35.0%) cases of AIP in the former 30 years versus 5 (45.5%) in the latter 10 years. There were 40 (5.9%) cases of TFCP among 675 patients in the former 30 years and 11 (0.9%) among 1289 patients in the latter 10 years. CONCLUSIONS: When the TFCP ratio of pancreatic resections and the AIP ratio of false-positive TFCPs were compared between the two periods, the TFCP ratio was 5.9% versus 0.9% and the AIP ratio was 35.0% versus 45.5%, respectively. It can thus be speculated that IgG4 measurement and EUS-FNA are absolutely imperative for the diagnosis of TFCP.

New approach of circumferential lymph node dissection around the superior mesenteric artery for pancreatic cancer during pancreaticoduodenectomy (with video).

PURPOSE: Various approaches have been reported for the resection of the nervous and lymphatic tissues around the superior mesenteric artery (SMA) during pancreaticoduodenectomy (PD) for pancreatic cancer. We developed a new procedure for circumferential lymph node dissection around the SMA to minimize local recurrence. METHODS: We included 24 patients who underwent PD with circumferential lymph node dissection around the SMA (circumferential dissection) and 94 patients who underwent classical mesopancreatic dissection (classical dissection) between 2019 and 2021. The technical details of this new method are described in the figures and videos, and the clinical characteristics and outcomes of this technique were compared with those of classical dissection. RESULTS: The median follow-up durations in the circumferential and classical dissection groups were 39 and 36 months, respectively. The patients' characteristics, including tumor resectability, preoperative and adjuvant chemotherapy rates, postoperative complication rates, and tumor stage, were similar between the two groups. No differences were observed in recurrence-free survival and overall survival between the two groups; however, the classical dissection group tended to have more local recurrences than the circumferential dissection group (8.3% vs. 33.3%, P = 0.168). Although no case of nodular-type recurrence after circumferential dissection was observed, 61.1% of local recurrences after classical dissection were of the nodular-type, and 36.4% were located on the left side of the SMA. CONCLUSIONS: Performing circumferential lymph node dissection around the SMA during PD can be conducted safely with minimal risks of local recurrence and may enhance the completeness of local resection.

Prediction of the invasion depth of superficial nonampullary duodenal adenocarcinoma.

OBJECTIVES: Distinguishing between intramucosal cancer and submucosal invasive cancer is vital for optimal treatment selection for patients with superficial nonampullary duodenal adenocarcinoma (SNADAC); however, standard diagnostic systems for diagnosing invasion depth are as yet undetermined. METHODS: Of 205 patients with SNADAC who underwent treatment at our institution between 2006 and 2022, 188 had intramucosal cancer and 17 had submucosal invasive cancer. The clinical, endoscopic, and pathological features used in the preoperative diagnosis of invasion depth and the diagnostic performance of endoscopic ultrasonography (EUS) were retrospectively analyzed in 85 patients. RESULTS: The oral side of the papilla tumor location, protruded or mixed macroscopic type, and moderately-to-poorly differentiated adenocarcinoma based on biopsy specimens were significantly more frequent in submucosal invasive cancer than in intramucosal cancer (88% vs. 48%; 94% vs. 42%; 47% vs. 0%, respectively). From the relationship between the endoscopic features and the submucosal invasive cancer incidence, submucosal invasion risk was stratified as: (i) low-risk (risk, 2%), all lesions located on the anal side of the papilla and superficial macroscopic type on the oral side of the papilla; and (ii) high-risk (risk, 23%), protruded or mixed macroscopic type on the oral side of the papilla. Based on the biopsy specimens, all eight patients with moderately-to-poorly differentiated adenocarcinoma had submucosal invasive cancer. Furthermore, EUS was not associated with invasion depth's diagnostic accuracy improvements. CONCLUSION: Optimal treatment indications for SNADAC can be selected based on the risk factors of submucosal invasion by tumor location, macroscopic type, and biopsy diagnosis.

KRAS variant allele frequency, but not mutation positivity, associates with survival of patients with pancreatic cancer.

KRAS mutation is a major driver of pancreatic carcinogenesis and will likely be a therapeutic target. Due to lack of sensitive assays for clinical samples of pancreatic cancer with low cellularity, KRAS mutations and their prognostic association have not been fully examined in large populations. In a multi-institutional cohort of 1162 pancreatic cancer patients with formalin-fixed paraffin-embedded tumor samples, we undertook droplet digital PCR (ddPCR) for KRAS codons 12/13/61. We examined detection rates of KRAS mutations by clinicopathological parameters and survival associations of KRAS mutation status. Multivariable hazard ratios (HRs) and 95% confidence intervals (CIs) for disease-free survival (DFS) and overall survival (OS) were computed using the Cox regression model with adjustment for potential confounders. KRAS mutations were detected in 1139 (98%) patients. The detection rate did not differ by age of tissue blocks, tumor cellularity, or receipt of neoadjuvant chemotherapy. KRAS mutations were not associated with DFS or OS (multivariable HR comparing KRAS-mutant to KRAS-wild-type tumors, 1.04 [95% CI, 0.62-1.75] and 1.05 [95% CI, 0.60-1.84], respectively). Among KRAS-mutant tumors, KRAS variant allele frequency (VAF) was inversely associated with DFS and OS with HRs per 20% VAF increase of 1.27 (95% CI, 1.13-1.42; ptrend <0.001) and 1.31 (95% CI, 1.16-1.48; ptrend <0.001), respectively. In summary, ddPCR detected KRAS mutations in clinical specimens of pancreatic cancer with high sensitivity irrespective of parameters potentially affecting mutation detections. KRAS VAF, but not mutation positivity, was associated with survival of pancreatic cancer patients.

Prediction of Recurrence Pattern of Pancreatic Cancer Post-Pancreatic Surgery Using Histology-Based Supervised Machine Learning Algorithms: A Single-Center Retrospective Study.

BACKGROUND: Patients with pancreatic cancer (PC) have poor prognosis and a high incidence of recurrence. Since further treatment is applicable for specific recurrent events, it is important to predict recurrence patterns after surgery. This study aimed to identify and predict early and late recurrence patterns of PC using a histology-based machine learning model. PATIENTS AND METHODS: Patients who underwent upfront curative surgery for PC between 2001 and 2014 were included. The timing of recurrence and prognosis of each first recurrence site were examined. A histology-based supervised machine learning method, which combined convolutional neural networks and random forest, was used to predict the recurrence and respective sites of metastasis. Accuracy was evaluated using area under the receiver operating characteristic curve (AUC). RESULTS: In total, 524 patients were included. Recurrence in the liver accounted for 47.8% of all recurrence events in the first year after surgery. Meanwhile, recurrence in the lung occurred later and could become apparent more than 5 years post-surgery, with indications for further surgery. In terms of substantial distant organ metastases, liver and lung metastases were identified as representative early and late recurrence events. The predictive AUCs of the machine learning model for training and test data were 1.000 and 0.861, respectively, and for predicting nonrecurrence were 1.000 for both. CONCLUSIONS: We identified the liver and lung as early and late recurrence sites, which could be distinguished with high probability using a machine learning model. Prediction of recurrence sites using this model may be useful for further treatment of patients with PC.

Immunogenic characteristics of microsatellite instability-low esophagogastric junction adenocarcinoma based on clinicopathological, molecular, immunological and survival analyses.

Microsatellite instability (MSI) is categorized by mutation frequency: high MSI (MSI-H), low MSI (MSI-L) and microsatellite stable (MSS). MSI-H tumors have a distinct immunogenic phenotype, with immunotherapies using checkpoint inhibitors already approved for the treatment of MSI-H gastroesophageal adenocarcinoma (GEA); this is not observed for MSI-L or MSS. Here, we tested the hypothesis that MSI-L tumors are also a distinct phenotype and potentially immunogenic. MSI-PCR assays (BAT25, BAT26, BAT40, D2S123, D5S346 and D17S250) were performed on 363 Epstein-Barr virus-negative, surgically resected esophagogastric junction (EGJ) adenocarcinoma samples. Tumors were characterized as MSI-H (≥2 markers), MSI-L (1 marker) or MSS (0 markers). CD8+ cell counts, PD-L1 and HER2 expression levels, TP53 mutations, epigenetic alterations and prognostic significance were also examined. All pathological and molecular experiments were conducted using serial, whole-tumor sections of chemo-naïve surgical specimens. MSI-H and MSI-L were assigned to 28 (7.7%) and 24 (6.6%) cases, respectively. Compared to MSS cases, MSI-L cases had significantly higher intratumoral CD8+ cell infiltration (P = .048) and favorable EGJ cancer-specific survival (multivariate hazard ratio = 0.35, 95% CI, 0.12-0.82; P = .012). MSI-L tumors were also significantly associated with TP53-truncating mutations as compared to MSI-H (P = .009) and MSS (P = .012) cases, and this trend was also observed in GEA data from The Cancer Genome Atlas (TCGA). Indel mutational burden among TCGA MSI-L tumors was significantly higher than that of MSS tumors (P = .016). These results suggest that MSI-L tumors may have a distinct tumor phenotype and be potentially immunogenic in EGJ adenocarcinoma.

Primary intramucosal synovial sarcoma of the sigmoid colon in a patient with a germline mutation in the MSH2 gene: A case report.

Synovial sarcoma is a high-grade soft tissue sarcoma that occurs primarily in the deep soft tissue of extremities, and primary colorectal synovial sarcoma is extremely rare. In this report, we present a synovial sarcoma mostly located within the mucosa of the sigmoid colon. The patient was a man in his forties with a germline deletion in the MSH2 gene. He had experienced undifferentiated pleomorphic sarcoma of the left forearm 7 years before and adenocarcinoma of the transverse colon 6 years before, both of which were successfully treated and exhibited no recurrence to date. A surveillance colonoscopy for Lynch syndrome revealed the tumor which had a submucosal tumor-like appearance with central erosion and endoscopic resection was performed. Histologically, it was composed of monotonous proliferation of spindle cells arranged in cellular fascicles; these findings were compatible with monophasic fibrous synovial sarcoma. In the tumor cells, the presence of the SS18-SSX1 fusion gene was confirmed. Protein expression of mismatch repair genes was intact in the tumor cells, indicating the association between microsatellite instability and synovial sarcoma was weak. The present case highlights a rare primary site of synovial sarcoma in a patient with Lynch syndrome.