Bridging horizons beyond CIRCULATE-Japan: a new paradigm in molecular residual disease detection via whole genome sequencing-based circulating tumor DNA assay.

Circulating tumor DNA (ctDNA) is the fraction of cell-free DNA in patient blood that originates from a tumor. Advances in DNA sequencing technologies and our understanding of the molecular biology of tumors have increased interest in exploiting ctDNA to facilitate detection of molecular residual disease (MRD). Analysis of ctDNA as a promising MRD biomarker of solid malignancies has a central role in precision medicine initiatives exemplified by our CIRCULATE-Japan project involving patients with resectable colorectal cancer. Notably, the project underscores the prognostic significance of the ctDNA status at 4 weeks post-surgery and its correlation to adjuvant therapy efficacy at interim analysis. This substantiates the hypothesis that MRD is a critical prognostic indicator of relapse in patients with colorectal cancer. Despite remarkable advancements, challenges endure, primarily attributable to the exceedingly low ctDNA concentration in peripheral blood, particularly in scenarios involving low tumor shedding and the intrinsic error rates of current sequencing technologies. These complications necessitate more sensitive and sophisticated assays to verify the clinical utility of MRD across all solid tumors. Whole genome sequencing (WGS)-based tumor-informed MRD assays have recently demonstrated the ability to detect ctDNA in the parts-per-million range. This review delineates the current landscape of MRD assays, highlighting WGS-based approaches as the forefront technique in ctDNA analysis. Additionally, it introduces our upcoming endeavor, WGS-based pan-cancer MRD detection via ctDNA, in our forthcoming project, SCRUM-Japan MONSTAR-SCREEN-3.

Whole-transcriptome sequencing in advanced gastric or gastroesophageal cancer: A deep dive into its clinical potential.

Advanced gastric and gastroesophageal junction cancers (GC/GEJCs) harbor diverse molecular signatures, highlighting the need for intricate evaluations to identify potential therapeutic targets. Although whole-transcriptome sequencing (WTS) has emerged as a useful tool for understanding these molecular intricacies, its clinical implications have yet to be fully elucidated. This study evaluated the correlation between immunohistochemistry (IHC) and WTS, compared their clinical significance, and identified potential therapeutic targets undetectable through IHC alone. We enrolled 140 patients with advanced GC/GEJC and assessed them using IHC for six pivotal biomarkers: claudin-18 (CLDN18), human epidermal growth factor receptor 2 (HER2), multiple receptor tyrosine kinases (RTKs), and programmed death ligand 1 (PD-L1). Concurrently, WTS was employed as part of the analyses in MONSTAR-SCREEN-2, a multicenter multiomics study. IHC analysis revealed 16.4% HER2, 39.3% CLDN18 (2+/3 + ≥75%), and 15.8% PD-L1 (combined positive score ≥ 10) positivity, among other molecular markers. Significant correlations were observed between IHC and WTS for all six pivotal biomarkers. Among nineteen HER2 IHC-positive patients treated with anti-HER2 therapeutics, ERBB2 status in WTS was significantly associated with progression-free survival (ERBB2-high vs. -low: median 9.0 vs. 5.6 months, log-rank p = 0.046). IHC-based molecular profiling revealed significantly high expression of CLDN18 in RTK-negative patients, with 78.4% positive for either CLDN18 or PD-L1. Additionally, WTS revealed elevated expression of pivotal biomarkers in patients displaying negative targetable biomarkers via IHC. Our findings highlighted the significant correlation between IHC and WTS, reinforcing the clinical utility of WTS. A subset with IHC-negative but WTS-positive status may benefit from specific biomarker-targeted therapies.

A multi-institutional randomized phase III study comparing minimally invasive distal pancreatectomy versus open distal pancreatectomy for pancreatic cancer; Japan Clinical Oncology Group study JCOG2202 (LAPAN study).

BACKGROUND: Minimally invasive distal pancreatectomy (MIDP), including laparoscopic and robotic distal pancreatectomy, has gained widespread acceptance over the last decade owing to its favorable short-term outcomes. However, evidence regarding its oncologic safety is insufficient. In March 2023, a randomized phase III study was launched in Japan to confirm the non-inferiority of overall survival in patients with resectable pancreatic cancer undergoing MIDP compared with that of patients undergoing open distal pancreatectomy (ODP). METHODS: This is a multi-institutional, randomized, phase III study. A total of 370 patients will be enrolled from 40 institutions within 4 years. The primary endpoint of this study is overall survival, and the secondary endpoints include relapse-free survival, proportion of patients undergoing radical resection, proportion of patients undergoing complete laparoscopic surgery, incidence of adverse surgical events, and length of postoperative hospital stay. Only a credentialed surgeon is eligible to perform both ODP and MIDP. All ODP and MIDP procedures will undergo centralized review using intraoperative photographs. The non-inferiority of MIDP to ODP in terms of overall survival will be statistically analyzed. Only if non-inferiority is confirmed will the analysis assess the superiority of MIDP over ODP. DISCUSSION: If our study demonstrates the non-inferiority of MIDP in terms of overall survival, it would validate its short-term advantages and establish its long-term clinical efficacy. TRIAL REGISTRATION: This trial is registered with the Japan Registry of Clinical Trials as jRCT 1,031,220,705 [ https://jrct.niph.go.jp/en-latest-detail/jRCT1031220705 ].

Prognostic Relevance of Primary Tumor Sidedness in Early-stage Colorectal Cancer: An Integrated Analysis of 4 Randomized Controlled Trials (JCOG2003A).

OBJECTIVE: The aim of this study was to determine the genuine prognostic relevance of primary tumor sidedness (PTS) in patients with early-stage colorectal cancer (CRC). BACKGROUND: The prognostic relevance of PTS in early-stage CRC remains a topic of debate. Several large epidemiological studies investigated survival only and did not consider the risk of recurrence so far. METHODS: Patients with stage II/III adenocarcinoma of the colon and upper rectum from 4 randomized controlled trials were analyzed. Survival outcomes were compared according to the tumor location: right-sided (cecum to transverse colon) or left-sided (descending colon to upper rectum). RESULTS: A total of 4113 patients were divided into a right-sided group (N=1349) and a left-sided group (N=2764). Relapse-free survival after primary surgery was not associated with PTS in all patients and each stage [hazard ratio (HR) adjusted =1.024 (95% CI: 0.886-1.183) in all patients; 1.327 (0.852-2.067) in stage II; and 0.990 (0.850-1.154) in stage III]. Also, overall survival after primary surgery was not associated with PTS in all patients and each stage [HR adjusted =0.879 (95% CI: 0.726-1.064) in all patients; 1.517 (0.738-3.115) in stage II; and 0.840 (0.689-1.024) in stage III]. In total, 795 patients (right-sided, N=257; left-sided, N=538) developed recurrence after primary surgery. PTS was significantly associated with overall survival after recurrence (HR adjusted =0.773, 95% CI: 0.627-0.954). CONCLUSIONS: PTS had no impact on the risk of recurrence for stage II/III CRC. Treatment stratification based on PTS is unnecessary for early-stage CRC.

Risk factors for loss of pulmonary function after wedge resection for peripheral ground-glass opacity dominant lung cancer.

OBJECTIVES: This study aimed to identify the risk factors for pulmonary functional deterioration after wedge resection for early-stage lung cancer with ground-glass opacity, which remain unclear, particularly in low-risk patients. METHODS: We analysed 237 patients who underwent wedge resection for peripheral early-stage lung cancer in JCOG0804/WJOG4507L, a phase III, single-arm confirmatory trial. The changes in forced expiratory volume in 1 s were calculated pre- and postoperatively, and a cutoff value of -10%, the previously reported reduction rate after lobectomy, was used to divide the patients into 2 groups: the severely reduced group (≤-10%) and normal group (>-10%). These groups were compared to identify predictors for severe reduction. RESULTS: Thirty-seven (16%) patients experienced severe reduction. Lesions with a total tumour size ≥1 cm were significantly more frequent in the severely reduced group than in the normal group (89.2% vs 71.5%; P = 0.024). A total tumour size of ≥1 cm [odds ratio (OR), 3.287; 95% confidence interval (CI), 1.114-9.699: P = 0.031] and pleural indentation (OR, 2.474; 95% CI, 1.039-5.890: P = 0.041) were significant predictive factors in the univariable analysis. In the multivariable analysis, pleural indentation (OR, 2.667; 95% CI, 1.082-6.574; P = 0.033) was an independent predictive factor, whereas smoking status and total tumour size were marginally significant. CONCLUSIONS: Of the low-risk patients who underwent pulmonary wedge resection for early-stage lung cancer, 16% experienced severe reduction in pulmonary function. Pleural indentation may be a risk factor for severely reduced pulmonary function in pulmonary wedge resection.

Total neoadjuvant therapy followed by a watch-and-wait strategy for patients with rectal cancer (TOWARd): protocol for single-arm phase II/III confirmatory trial (JCOG2010).

BACKGROUND: Radical surgery is the standard treatment for rectal cancer, but can impact quality of life. Recently, the concept of total neoadjuvant therapy with a watch-and-wait strategy has been proposed in which patients with a cCR after total neoadjuvant therapy do not proceed to surgery. However, most investigations of a watch-and-wait strategy have reported cases where cCR was achieved coincidentally via total neoadjuvant therapy. The aim is to assess whether total neoadjuvant therapy is effective in early-stage rectal cancer in patients that achieve cCR and are offered a watch-and-wait strategy. METHODS: JCOG2010 (TOWARd) is a multi-institutional, single-arm phase II/III confirmatory investigation of the safety and efficacy of total neoadjuvant therapy followed by a watch-and-wait strategy for rectal cancer. Key eligibility criteria include cT2-3 N0 M0 rectal adenocarcinoma, tumour diameter less than or equal to 5 cm, age 18-75 years, performance status 0-1, and no history of pelvic irradiation or rectal surgery. Total neoadjuvant therapy involves neoadjuvant chemoradiotherapy (capecitabine and radiotherapy: 45 Gy/25 fractions to the whole pelvis plus boost of 5.4 Gy/3 fractions to the primary tumour) followed by consolidation chemotherapy (four cycles of capecitabine/oxaliplatin). Patients will be re-staged every 8 weeks after total neoadjuvant therapy, and those who achieve cCR will undergo a watch-and-wait strategy, those with near complete response will undergo a watch-and-wait strategy or local resection, and those with an incomplete response will undergo radical surgery. The primary endpoint is the cCR rate in phase II and 5-year overall survival in phase III. Secondary endpoints include postoperative anal, urinary, and sexual function. A total of 105 patients (phase II, 40 patients; phase III, 65 patients) will be enrolled over 3.5 years. CONCLUSION: This trial will determine whether total neoadjuvant therapy and a watch-and-wait strategy is an effective alternative to radical surgery for early-stage rectal cancer in patients with cT2-3 N0 M0 and tumour size less than or equal to 5 cm. REGISTRATION NUMBER: jRCTs031220288 (https://jrct.niph.go.jp/en-latest-detail/jRCTs031220288).

Randomized phase II study comparing neoadjuvant 5-fluorouracil/oxaliplatin/docetaxel versus docetaxel/oxaliplatin/S-1 for patients with type 4 or large type 3 gastric cancer.

Macroscopic type 4 and large type 3 gastric cancer, mostly overlapping with scirrhous or linitis plastica type, exhibit a highly invasive nature and show unfavorable prognosis after curative surgery, even with adjuvant chemotherapy. A randomized phase III trial (JCOG0501) failed to demonstrate a survival advantage of neoadjuvant chemotherapy with S-1 plus cisplatin for this population. The current authors initiated a randomized phase II study comparing neoadjuvant chemotherapy with 5-fluorouracil/oxaliplatin/docetaxel versus docetaxel/oxaliplatin/S-1 for type 4 and large type 3 gastric cancer. 76 patients are planned to be enrolled over two years. The primary end point is the proportion of patients with a pathological response (grade 1b or higher) and secondary end points include overall survival and adverse events. Clinical Trial Registration: jRCTs031230231 (rctportal.niph.go.jp).

A randomized phase II study comparing preoperative mFOLFOX6 versus FOLFOXIRI for locally advanced colon cancer: JCOG2006.

The prognosis of locally advanced colon cancer (LACC) with surgical resection followed only by adjuvant chemotherapy is poor. Preoperative chemotherapy for LACC patients with risk factors such as cT4bN+ or cT3-4aN2-3 has attracted attention. Here, the authors describe the rationale and design of JCOG2006, a randomized phase II study comparing preoperative chemotherapy with mFOLFOX6 versus FOLFOXIRI for LACC. Their efficacy and safety are evaluated and a determination of which is the more promising treatment will be conducted in a subsequent phase III trial. A total of 86 patients will be accrued from 44 institutions over 2 years. The primary end point is the proportion of patients with a Tumor Regression Score of 0-2, and secondary end points include overall survival, response rate and adverse events. Clinical Trial Registration: jRCTs031210365 (https://jrct.niph.go.jp/).

Utility of circulating tumour DNA for prognosis and prediction of therapeutic effect in locally recurrent rectal cancer: study protocol for a multi-institutional, prospective observational study (JCOG1801A1, CAP-LR study).

INTRODUCTION: In locally recurrent rectal cancer (LRRC), surgery is a standard treatment for resectable disease. However, short-term and long-term outcomes are unsatisfactory due to the invasive nature of surgical procedures and the high proportion of local recurrence. Consequently, the identification of reliable prognostic and predictive biomarkers to guide treatment decisions may improve outcomes. The presence of circulating tumour DNA (ctDNA) in plasma after surgery may signify the presence of minimal residual disease (MRD) in various cancers. Therefore, we have launched a multi-institutional prospective observational study of ctDNA for MRD detection in conjunction with JCOG1801, a randomised, controlled phase III trial evaluating the efficacy of preoperative chemoradiotherapy (pre-CRT) compared with up-front surgery for LRRC (jRCTs031190076, NCT04288999). METHODS AND ANALYSIS: JCOG1801A1 is the first correlative study that assesses ctDNA in LRRC patients enrolled in JCOG1801. Patients randomised to up-front surgery will provide whole blood samples at three time points (prior to surgery, after surgery and after postoperative chemotherapy); those to pre-CRT will provide at five time points (prior to pre-CRT, after pre-CRT, prior to surgery, after surgery and after postoperative chemotherapy). Cell-free DNA will be extracted from plasma and analysed by Guardant Reveal, a tumour tissue-agnostic assay that assesses both genomic alterations and methylation patterns to determine the presence or absence of ctDNA. We will compare the prognosis and treatment response of patients according to their ctDNA status after surgery and at other time points. ETHICS AND DISSEMINATION: The study protocol received approval from the Institutional Review Board of National Cancer Center Hospital East on behalf of the participating institutions in February 2023. The study is conducted in accordance with the precepts established in the Declaration of Helsinki and Ethical Guidelines for Medical and Biological Research Involving Human Subjects. Written informed consent will be obtained from all eligible patients prior to registration.

Phase II biomarker identification study of anti-VEGF agents with FOLFIRI for pretreated metastatic colorectal cancer.

Chemotherapy plus antiangiogenic agents, including bevacizumab, ramucirumab and aflibercept, is a standard second-line treatment for patients with metastatic colorectal cancer, but which specific agents should be selected is ambiguous due to a lack of clear evidence from prospective studies. Previous reports have suggested ramucirumab and aflibercept could be more effective than bevacizumab in patients with high VEGF-D and high VEGF-A, respectively. JCOG2004 is a three-arm, randomized, phase II study to identify predictive biomarkers for these agents in patients who have failed first-line treatment. The study will enroll 345 patients from 52 institutions for 2 years, with progression-free survival in high VEGF-D (bevacizumab vs ramucirumab) and high VEGF-A (bevacizumab vs aflibercept) serving as the primary end point. Clinical Trial Registration: jRCTs031220058 (www.jrct.niph.go.jp).

Identifying Risk Factors of Complications following Total Gastrectomy for Gastric Cancer: Comparison between Splenectomy and Spleen-Preserving Surgery - A Supplementary Analysis of JCOG0110.

INTRODUCTION: Splenectomy for proximal gastric cancer was found to offer no survival benefit in a randomized trial clarifying the role of splenectomy (JCOG0110 study). Although many studies have explored risk factors for morbidities following total gastrectomy, none have assessed the risk factors for postoperative complications in spleen-preserving total gastrectomy. METHODS: Using data from 505 patients enrolled in a previous randomized trial, risk factors for postoperative complications were identified by multivariable logistic regression analysis. Then, the risk factors were assessed separately between splenectomy and spleen-preserving total gastrectomy. RESULTS: Postoperative complications were identified in 119 patients (23.6%) and were more common following splenectomy than following spleen-preserving surgery (30.7% and 16.1%, respectively, p < 0.01). Multivariable analysis revealed that age ≥65 years (p = 0.032), body mass index ≥25 (p = 0.003), and blood loss ≥350 (p = 0.019) were independent risk factors for postoperative complications in the entire cohort. Among them, only body mass index was a significant independent risk factor for complications in both spleen preservation (p = 0.047) and splenectomy groups (p = 0.017). CONCLUSION: Risk factors for postoperative complications were essentially the same between splenectomy and spleen preservation. Being overweight increased the risk of postoperative complications.

A multi-institutional randomized phase III trial comparing postoperative radiotherapy to observation after adjuvant chemotherapy in patients with pathological N2 Stage III non-small cell lung cancer: Japan Clinical Oncology Group Study JCOG1916 (J-PORT study).

The standard treatment for pathological N2 Stage III non-small cell lung cancer with negative surgical margins in Japan is cisplatin-based adjuvant chemotherapy. However, recent studies suggest that the addition of thoracic radiotherapy after adjuvant chemotherapy prolongs survival. While thoracic radiotherapy is considered to prolong survival by improving locoregional control, it is known to increase radiation-induced adverse events. We began a randomized controlled trial in January 2021 in Japan to confirm the superiority of radiotherapy over observation after adjuvant chemotherapy in pathological N2 Stage III non-small cell lung cancer patients with negative surgical margins. We aim to accrue 330 patients from 47 institutions over 5 years. The primary endpoint is relapse-free survival; the secondary endpoints are overall survival, proportion of patients completing radiotherapy in the radiotherapy arm, early adverse events, late adverse events in the radiotherapy arm, serious adverse events and local recurrence.

Clinical significance of chromatin remodeling factor CHD5 expression in gastric cancer.

Chromodomain helicase DNA-binding 5 (CHD5), which is a member of the CHD family, has been identified as a tumor suppressor gene in a variety of malignancies. The aim of the current study was to clarify the clinical significance of CHD5 expression in gastric cancer. CHD5 expression was evaluated using immunohistochemistry (IHC) in 154 specimens resected from patients with gastric cancer from January 2011 to December 2013, and assessed its relationships with clinicopathological characteristics and survival. In vitro cell proliferation, invasion, and migration assays and western blotting analysis were performed to clarify the role of CHD5 in human gastric cancer cell lines. Of a total of 154 patients, 57 (37.0%) exhibited low CHD5 expression, which was significantly associated with positive lymphatic invasion (P=0.032), advanced pT status (P=0.011), and advanced pStage (P=0.014). Overall survival (OS) in patients with low CHD5 expression was significantly worse compared with patients with high CHD5 expression (hazard ratio, 1.96; 95% confidence interval, 1.09-3.45; log-rank P=0.023). Cox multivariate analysis for OS revealed that CHD5 expression was an independent prognostic factor with age and pN status. In vitro, the upregulation of CHD5 in gastric cancer cells with low CHD5 expression significantly decreased cell proliferation, migration and invasion. CHD5 was associated with the regulation of multiple cancer-related targets, including p53 and enhancer of zeste homolog 2 (EZH2) in western blotting analysis. In conclusion, since CHD5 regulated multiple cancer-related targets, its expression may be a useful prognostic biomarker in patients with gastric cancer.

The Pattern of Residual Tumor After Neoadjuvant Chemotherapy for Locally Advanced Esophageal Cancer and Its Clinical Significance.

OBJECTIVES: To investigate the residual pattern of esophageal cancer in the esophageal wall after neoadjuvant chemotherapy (NAC) and its clinical significance. BACKGROUND: NAC is a standard treatment for locally advanced esophageal cancer; however, residual tumor patterns in resected specimens after NAC and their clinico-pathological characteristics remain unknown. METHODS: One hundred twenty consecutive patients with cT3 or deeper esophageal cancer underwent curative esophagectomy after NAC and achieved grade 2 histological responses between 2000 and 2016. Hematoxylin-eosin staining of residual tumor sections revealed 4 remnant categories: Type 1: shallow, Type 2: central, Type 3: deep, and Type 4: diffuse. We examined associations between these Types and clinico-pathological factors, including prognosis. RESULTS: Forty-five (38%) specimens had no residual tumor cells in the mucosal layer. The adventitia layer displayed the lowest residual tumor cell frequency (18%) among all layers. Types 1, 2, 3, and 4 residual tumor patterns were found in 49 (41%), 33 (28%), 9 (8%), and 29 (24%) patients, respectively. Type 4 showed the maximum standard uptake value after NAC; Types 3 and 4 had higher ratios of venous invasion than Type 1 or 2. Patients with Type 3 or 4 more frequently developed pleural dissemination or distant metastasis than patients with Type 1 or 2. Survival was similar among the 4 Types. CONCLUSIONS: After NAC for locally advanced esophageal cancer, the shallow residual tumor pattern was most common, but approximately 40% of specimens showed no tumor cells in the mucosal layer. Deep and diffuse remnant patterns were associated with high risks of pleural dissemination and distant metastasis.

What is the most useful body composition parameter for predicting toxicities of preoperative chemotherapy for gastric cancer?

PURPOSE: Preoperative chemotherapy is an effective treatment option for resectable gastric cancer, but it is associated with various adverse events (AEs). This study aimed to identify the body composition parameters that most accurately predicted the incidence of AEs in preoperative chemotherapy for gastric cancer. METHODS: The present study included a total of 114 patients who received preoperative chemotherapy for resectable gastric cancer. We estimated various body composition parameters using computed tomography images obtained before preoperative chemotherapy. Their associations with the incidence of hematological (grade ≥ 3) and non-hematological (grade ≥ 2) AEs were analyzed by multivariate logistic regression analyses. RESULTS: Seventy-two of the 114 (63.2%) patients experienced hematological AEs (grade ≥ 3), specifically neutropenia in 68 (59.6%), anemia in 5 (4.9%), and thrombocytopenia in 3 (2.6%). Meanwhile, 59 patients (51.8%) experienced non-hematological AEs (grade ≥ 2), namely hypoalbuminemia in 31 (27.2%), anorexia in 24 (21.1%), and febrile neutropenia in 17 (14.9%). Multivariate analyses revealed that a low psoas muscle index (PMI) was an independent risk factor for the incidence of both hematological and non-hematological AEs. CONCLUSIONS: Patients with a low PMI experienced an increased incidence of hematological and non-hematological toxicities during preoperative chemotherapy for gastric cancer. Clinicians should be aware of these risks in this population.

Postoperative Long-Term Outcomes in Elderly Patients with Gastric Cancer and Risk Factors for Death from Other Diseases.

BACKGROUND: Elderly patients with gastric cancer are frequently treated surgically in current clinical practice. Although several studies have investigated short-term outcomes after gastrectomy in elderly patients, most did not evaluate long-term outcomes. METHODS: We analyzed 1154 consecutive patients who underwent curative gastrectomy for gastric cancer between 2001 and 2013. We classified them into two groups: the elderly group (n = 241), consisting of patients aged ≥75 years, and the non-elderly group (n = 913), consisting of patients aged <75 years, and compared the short- and long-term outcomes between the two groups. The risk factors for death from other diseases in elderly patients were also examined. RESULTS: Although the incidence of postoperative pneumonia was significantly higher in the elderly group (P < 0.001), the proportion of overall postoperative complications did not differ significantly between the two groups (P = 0.097). The disease-specific survival was similar between the two groups (P = 0.743), whereas the overall survival in the elderly group was significantly shorter than that in the non-elderly group (P < 0.001) because of a higher incidence of death from other diseases throughout all gastric cancer stages. Multivariate analysis revealed that a low preoperative prognostic nutrition index (PNI) and multiple comorbidities were significant risk factors for death from other diseases within 5 years in the elderly group. CONCLUSIONS: Despite acceptable short-term outcomes, long-term outcomes in elderly patients with gastric cancer were poor due to the high incidence of death from other diseases. Indications for surgery in elderly patients with a low PNI or multiple comorbidities should be considered carefully.

Clinicopathological characteristics and survival of primary malignant melanoma of the esophagus.

Primary malignant melanoma of the esophagus (PMME) has been reported to be a rare and highly malignant disease, and to date a standard treatment strategy has not been established due to limited evidence. The aim of the present study was to investigate the clinicopathological characteristics of this extremely rare disease. A total of 6 out of 2,093 patients with PMME treated in our institution between 1995 and 2016 were retrospectively analyzed and their clinicopathological parameters including treatment course and long-term survival were investigated. The major clinicopathological characteristics of patients were that they were >70 years of age, male sex, dysphagia at first diagnosis, and macroscopic black protruding tumors located in the lower third of the thoracic esophagus. Four of the five patients receiving pretherapeutic endoscopic biopsy were correctly diagnosed with PMME, and two patients received preoperative treatment with ineffective histopathological responses. There were two unresectable cases, one was treated with an immune-checkpoint inhibitor and the other received palliative care. Three of the four patients receiving curative surgery developed hematogenous recurrence within two years of surgery and only one patient with pT1aN0M0 achieved long-term survival. The median overall survival of all six patients was 19.6 (6.4-40.5) months. Patients with stage I disease exhibited significantly more favorable prognoses than those with stage II-IV (P=0.025) and surgically-treated patients had significantly better prognoses than those who did not receive surgery (P=0.018). In conclusion, PMME was associated with highly malignant features and tended to develop hematogenous metastases even after radical resection. Early diagnosis appears to be important to cure this refractory disease.

Predictive value of MLH1 and PD-L1 expression for prognosis and response to preoperative chemotherapy in gastric cancer.

BACKGROUND: Microsatellite instability (MSI) and programmed death-ligand 1 (PD-L1) are candidate predictors for the response to immune checkpoint inhibitors, and may predict chemotherapy sensitivity. We investigated the simultaneous expression of mutL homolog 1 (MLH1), a mismatch repair gene, and PD-L1 in gastric cancers. METHODS: We examined MLH1 and PD-L1 expression in surgical specimens from 285 gastric cancer patients treated with or without preoperative chemotherapy, and assessed the relation between expression results and both histological response and recurrence-free survival (RFS). RESULTS: Of 285 patients, 28 (9.8%) and 70 (24.6%) exhibited negative MLH1 and high PD-L1 expression, respectively. Most MLH1-negative tumors (85.7%) showed high MSI, and these tumors exhibited high PD-L1 expression more frequently than MLH1-positive tumors (57.1% vs. 21.0%, P < 0.001). MLH1-negative patients were significantly less likely to respond to preoperative chemotherapy than MLH1-positive patients (16.7% vs. 61.2%, P = 0.005), whereas there was no significant difference between high- and low-PD-L1 expression patients (55.9% vs. 56.6%, P = 0.95). RFS in patients without preoperative chemotherapy was significantly longer in the MLH1-negative group than in the MLH1-positive group (HR 0.30; 95% CI 0.09-0.95; P = 0.030), whereas in patients with preoperative chemotherapy there was no significant difference in RFS between the two groups (HR 0.70; 95% CI 0.30-1.63; P = 0.41). PD-L1 expression was not associated with RFS in patients with or without chemotherapy. CONCLUSIONS: Loss of MLH1 was associated with chemoresistance and did not prolong survival following neoadjuvant chemotherapy. The strong association between MLH1 and MSI status suggests that immune checkpoint inhibitors may be preferable to conventional chemotherapy for MLH1-negative gastric cancer.

Surgical Treatment of Gastroesophageal Junction Cancer.

Although the incidence of gastroesophageal junction (GEJ) adenocarcinoma has been increasing worldwide, no standardized surgical strategy for its treatment has been established. This study aimed to provide an update on the surgical treatment of GEJ adenocarcinoma by reviewing previous reports and propose recommended surgical approaches. The Siewert classification is widely used for determining which surgical procedure is used, because previous studies have shown that the pattern of lymph node (LN) metastasis depends on tumor location. In terms of surgical approaches for GEJ adenocarcinoma, a consensus was reached based on two randomized controlled trials. Siewert types I and III are treated as esophageal cancer and gastric cancer, respectively. Although no consensus has been reached regarding the treatment of Siewert type II, several retrospective studies suggested that the optimal treatment strategy includes paraaortic LN dissection. Against this background, a Japanese nationwide prospective trial is being conducted to determine the proportion of LN metastasis in GEJ cancers and to identify the optimal extent of LN dissection in each type.