Background Chemotherapy is recommended for metastatic colorectal cancer (mCRC). However, chemotherapy may be interrupted by malignant left-large bowel obstruction (MLLBO). The aim of this study was to investigate the oncologic outcomes and risk factors for MLLBO in metastatic left-sided colon cancer (mLCC) patients undergoing chemotherapy. Methods Three large medical centers in Sichuan province, Southwest of China, took part in this multicenter retrospective cohort study. Consecutive mLCC patients who received chemotherapy from June 2012 to July 2021 at those centers were divided into two groups based on whether MLLBO occurred during chemotherapy. Patients were propensity score matched (PSM) at a ratio of 1:2 into MLLBO and non-MLLBO groups. Univariable and multivariable Cox proportional hazards regression models were used to identify predictors of survival. Results Among 1,638 mLCC patients, 156 were included in the matched cohort. The median overall survival was 37.5 months in the non-MLLBO group and 28.0 months in the MLLBO group (p = 0.018). The corresponding median cancer-specific survival was 39.0 months in the non-MLLBO group and 30.0 months in the MLLBO group (p = 0.02). Multivariable Cox regression analysis showed that MLLBO was independently associated with reduced overall survival (hazard ratio [HR] = 1.473, 95% CI: 1.186-1.812, P < 0.001) and cancer-specific survival (HR = 1.619, 95% CI: 1.391-1.899, P < 0.001). Additionally, tumor length ≥5 cm (P = 0.043) and TTI ≥1.5 cm (P < 0.001) were identified as independent risk factors for MLLBO. Conclusion Patients without MLLBO had a better prognosis than those with MLLBO during chemotherapy. Preventive measures are recommended for mLCC patients at higher risk of developing MLLBO during chemotherapy.

Representativeness of Study Participants

Supplementary Material 5. Summary of patient characteristics (grouped by baseline ctDNA status).

Supplementary Material 4. Criteria of the pathological tumor regression grade (pTRG).

Double-Negative T (DNT) cells, lacking both CD4 and CD8 expression, play critical roles in cancer immunology, and have garnered increasing attention in cancer research. However, their heterogeneity and functional diversity within the tumor microenvironment (TME) remain underexplored. In-house and publicly available single-cell RNA sequencing (scRNA-seq) data for different cancer types were integrated after quality control and batch effect correction, followed by DNT cells separation from CD3+ T cells subtypes. Functional characteristics, intercellular communication, differentiation trajectories, regulatory networks, and clinical relevance were analyzed among different DNT subsets. Key findings were validated using multiplex immunofluorescence and spatial transcriptomics to investigate the spatial localization of DNT subsets and their interactions within the TME. Impact of γδ T cells on immunotherapy response was also assessed using MC38-based murine tumor model. By integrating scRNA-seq data from 2,369 samples across 23 cancer types, we established a comprehensive single-cell atlas of 157,025 high-quality DNT cells. Fourteen distinct DNT subsets (6 αβ DNT and 8 γδ T cell subsets) were identified, demonstrating tumor both type-specific and shared distribution patterns, as well as unique cell-cell interaction network within the TME. These subsets displayed specialized functional profiles, including cytotoxicity, antigen presentation, and immune modulation, indicating that the functional diversity of DNT cells is largely subset-specific rather than a manifestation of multifunctionality within a single population. We also delineated divergent trajectories for αβ DNT and γδ T cell subsets, including the functional plasticity of gut-resident γδ T cells transitioning between cytotoxic and immunosuppressive states. Notably, several DNT subsets were significantly associated with favorable clinical treatment outcomes, including improved responses to cancer immunotherapy. Consistently, depletion of γδ T cells in the murine tumor model significantly decreased the efficacy of PD-1 blockade, underscoring their critical role in therapeutic response. Our study uncovers the previously underappreciated heterogeneity and functional diversity of DNT cells in the TME and demonstrates their profound impact on tumor progression and immunotherapy outcomes.

Supplementary Material 9. Univariate and multivariate analysis for poor responders to neoadjuvant chemotherapy and dynamic ctDNA satus: subgroup analysis between low-risk and recurred ctDNA positive groups.

The high prevalence of cancer immunotherapy resistance, coupled with substantial tumor heterogeneity, underscores the urgent need for innovative therapeutic targets. A deeper understanding of immunoregulatory mechanisms would provide new targets and combination therapeutic strategies for tumor therapy. In this study, we demonstrate that HSD17B12 enhances anti-tumor immunity and represents a promising therapeutic target. Mechanistically, HSD17B12 promotes lysosome-dependent degradation of PD-L1 via the VAC14 and ESCRT complexes across various malignancies, regardless of its 3-ketoacyl-CoA reductase activity. HSD17B12-deficient cells displayed PD-L1 accumulation in both tumor cells and exosomes, reducing T cell-mediated cytotoxicity. Notably, we found a significant negative correlation between HSD17B12 and PD-L1 expression in colorectal cancer tissues. Furthermore, high HSD17B12 expression in CRC correlated with increased infiltration of cytotoxic T cells. Based on these findings, we designed a peptide, HSD-CC1-NPGY, which effectively reduces PD-L1 expression in cells and suppresses tumor growth in a mouse model. Overall, our results establish HSD17B12 as an important regulator of anti-tumor immunity and a promising therapeutic target for cancer treatment.

Supplementary Material 7. Univariate and multivariate analysis for poor responders to neoadjuvant chemotherapy and dynamic ctDNA status.

Supplementary Material 2. The list of 769 genes in the NGS panel.

Aging is linked to a higher incidence of gut diseases such as inflammatory bowel disease (IBD), yet the underlying mechanisms remain unclear. We identified an age-related decline in magnesium (Mg) levels specifically in the gut across species, prompting investigation of its role in intestinal health. Functional studies demonstrated that Mg restriction accelerates gut aging in old but not in young mice and aggravates colitis severity. Multi-omics analysis of mouse tissues revealed that dietary Mg deficiency reshapes the phosphoproteome and N-glycoproteome, destabilizing adhesion complexes, a hallmark of intestinal aging and inflammation. In the UK Biobank cohort (n = 182,213), dietary Mg intake was inversely correlated with gut disorder risk, with 334.7-420.0 mg/day conferring significant protection against Crohn's disease, ulcerative colitis, irritable bowel syndrome, and diverticular disease. These findings identify Mg homeostasis as a key regulator of gut health and highlight Mg supplementation as a potential strategy to counteract age-related gut dysfunction.

Supplementary Material 1. Details of the inclusion, exclusion, and withdrawal criteria.

BACKGROUND: Large-scale evidence on the role of endoscopy alone as the assessment tool to identify complete response after neoadjuvant therapy in locally advanced rectal cancer, particularly across different neoadjuvant therapy regimens, is scarce. OBJECTIVE: This study aims to evaluate the diagnostic accuracy of endoscopy for predicting luminal complete response after neoadjuvant therapy and compare its performance between patients receiving neoadjuvant chemotherapy and neoadjuvant chemoradiotherapy. DESIGN: Retrospective cohort study. SETTINGS: The study was conducted at a teaching hospital. PATIENTS: A total of 349 locally advanced rectal cancer patients (223 neoadjuvant chemotherapy, 126 neoadjuvant chemoradiotherapy) who underwent neoadjuvant therapy and restaging endoscopy were included. INTERVENTIONS: Three reviewers assessed endoscopic images independently to determine the occurrence of endoscopic complete response. MAIN OUTCOME MEASURES: The diagnostic accuracy for predicting pathological luminal complete response (ypT0) was calculated. RESULTS: The overall accuracy of endoscopy for predicting complete response was 92.0% (321/349), with a positive predictive value of 69.6%, sensitivity of 69.6% and specificity of 95.4%. A flat scar was the most predictive feature (positive predictive value = 70.3%). The sensitivity of endoscopic performance was significantly higher in the neoadjuvant chemoradiotherapy group compared to the neoadjuvant chemotherapy group (90.0% vs. 53.8%, p = 0.008), despite comparable overall accuracy and area under the curve. The addition of biopsy did not significantly improve diagnostic ability. Inter-reviewer agreement was substantial to excellent (κ=0.754-0.883). LIMITATIONS: No video or artificial intelligence was involved. CONCLUSIONS: Endoscopy is an optional tool for identifying luminal complete response after neoadjuvant therapy. Its sensitivity is lower after neoadjuvant chemotherapy than after neoadjuvant chemoradiotherapy, warranting caution against missed diagnoses. Beyond the flat scar, other features like small flat ulcers also have a non-negligible complete response rate. The role of routine biopsy still needs further exploration. See Video Abstract.

Supplementary Material 3. Methods for Bioinformatical analysis

Supplementary Material 10. Univariate and multivariate analysis for poor responders to neoadjuvant chemotherapy and preoperative ctDNA status.

Supplementary Material 8. Univariate and multivariate analysis for poor responders to neoadjuvant chemotherapy and dynamic ctDNA status: subgroup analysis between low-risk and delayed/no clearance groups.

Surgery remains curative for esophageal gastrointestinal stromal tumors (GISTs), while debates persist between minimally invasive enucleation and radical esophagectomy. Limited evidence from case reports and small cohorts necessitates a systematic evaluation to guide clinical decisions. This review showed that enucleation may be considered for small and low-mitotic-index esophageal GISTs with benign tendency. Despite higher R1 and tumor rupture rates, survival outcomes were comparable to esophagectomy. Enucleation, including endoscopic enucleation, was safe and effective in selected cases.

ABSTRACT Early‐onset colorectal cancer (EOCRC) is increasing worldwide, yet the molecular basis underlying its age‐related heterogeneity remains insufficiently defined. To address this gap, we performed whole‐exome sequencing in a Chinese EOCRC cohort diagnosed before 40 years of age ( n = 111), bulk transcriptome sequencing in a subset of these tumors ( n = 59), and whole‐exome sequencing in an independent Chinese colorectal cancer cohort spanning a broader age range ( n = 210). We then integrated these data with publicly available somatic mutation, bulk RNA‐seq, and single‐cell transcriptomic datasets to characterize age‐associated tumor‐intrinsic and microenvironmental features. Genomic analyses revealed a distinct EOCRC landscape, including lower frequencies of APC and KRAS mutations, more frequent SMAD4 disruption through mutation or copy‐number loss, and enrichment of the PTPRK‐RSPO3 fusion. Single‐cell analyses further showed increased infiltration of CD4 + memory T cells and mast cells in EOCRC, whereas later‐onset colorectal cancer was characterized by SPP1 + macrophage predominance and a strengthened interaction axis between FAP + cancer‐associated fibroblasts and SPP1 + macrophages. Therapeutic evaluation in aged mouse models, together with single‐cell analysis of immunotherapy‐treated patients, indicated reduced PD‐1 blockade efficacy with increasing age. Together, these findings support age‐informed molecular classification and therapeutic stratification in colorectal cancer.

BACKGROUND:Recurrence of colorectal cancer (CRC) after curative-intent treatment is largely driven by minimal residual disease (MRD). Circulating tumor DNA (ctDNA) offers a noninvasive approach to detect MRD and tailor adjuvant therapy and surveillance. METHODS:This scoping review synthesized prospective cohorts, interventional/randomized trials, and real-world registries on ctDNA-based MRD testing in resected CRC, comparing tumor-informed vs plasma-only (mutation- and/or methylation-based) assays. RESULTS:Postoperative ctDNA positivity strongly predicts recurrence and often precedes radiologic relapse by 3 to 10 months. Tumor-informed assays provide high specificity and analytical sensitivity, whereas plasma-only assays enable tissue-free, faster testing but often require serial sampling. In stage II colon cancer, ctDNA-guided management reduced the use of chemotherapy without compromising recurrence-free survival. ctDNA dynamics add prognostic resolution. Clearance after adjuvant therapy is associated with excellent outcomes, whereas persistent positivity signals a very high relapse risk. Escalation approaches tested to date (eg, intensified chemotherapy or trifluridine/tipiracil) have not shown definitive disease-free survival gains in patients with a positive ctDNA. Implementation data indicate that ctDNA can influence treatment and surveillance decisions. However, barriers include assay variability, optimal timing, counseling, and reimbursement. CONCLUSION:ctDNA-based MRD testing is a robust prognostic tool and a practical framework for biology-guided postoperative CRC care. Ongoing phase III trials should establish standardized algorithms and effective MRD-directed therapies.

Supplementary Material 6. Distribution of dynamtic ctDNA status.

PURPOSE:Neoadjuvant chemotherapy (NCT) has been accepted as the standard management for locally advanced rectal cancer (LARC) without high-risk factors. However, many patients experience poor pathologic response, necessitating early-prediction tools. We investigated dynamic circulating tumor DNA (ctDNA) analysis for early response monitoring in patients with LARC undergoing NCT. EXPERIMENTAL DESIGN:In this biomarker substudy of the multicenter randomized COPEC trial, 153 patients with low-/intermediate-risk LARC were enrolled. Plasma samples (n = 526) were collected at baseline and after each cycle of NCT. ctDNA was analyzed via tumor-informed sequencing. Patients were classified by dynamic status into high-risk (delayed/no clearance and recurred positive) and low-risk (early clearance and persistent negative) groups. Poor response was defined as pathologic tumor regression grade (pTRG) 3 or distant metastasis. The association between ctDNA status and responses was analyzed. RESULTS:No patient with high-risk ctDNA dynamics achieved a major pathologic response (pTRG 0-1). The poor response rate was 59.4% in the high-risk group versus 12.4% in the low-risk group (P < 0.001). High-risk dynamic ctDNA status was a strong independent predictor of poor response (OR = 11.69; 95% confidence interval, 5-27.25; P < 0.001). Both delayed/no clearance (OR = 12.64; P < 0.001) and recurred positivity (OR = 8.91; P < 0.001) were significant risk factors. A single preoperative ctDNA-positive result also predicted poor response (OR = 11.27; P < 0.001). CONCLUSIONS:Dynamic ctDNA monitoring identifies patients with LARC at high risk for NCT failure as early as two cycles into treatment, which can form the basis for an adaptive trial design and eventual personalization of therapy selection.