Locally Advanced Rectal Cancer Patients Research Articles

Circulating DNA in Rectal Cancer to Unravel the Prognostic Potential for Radiation Oncologist: A Meta-analysis.

Liquid biopsy, with its noninvasive nature and ability to detect tumor-specific genetic alterations, emerges as an ideal biomarker for monitoring recurrences for locally advanced rectal cancer (LARC). Completed studies have small sample sizes and different experimental methods. To consolidate and assess the collective evidence regarding the prognostic role of circulating DNA (ctDNA) detection in LARC patients undergoing neoadjuvant chemoradiotherapy (nCRT). Computerized bibliographic searches of MEDLINE and CANCERLIT (2000 to 2023) were supplemented with hand searches of reference lists. Study selection: studies evaluating oncological outcomes of patients with LARC treated with a nCRT comparing patients with positive and negative liquid biopsy at baseline and after nCRT. Data extraction: data on population, intervention, and outcomes were extracted from each study, in accordance with the intention to treat method, by 2 independent observers, and combined using the DerSimonian method and Laird method. Nine studies follow inclusion criteria including 678 patients treated with nCRT. The pooled RD rate of ctDNA negative between measure at baseline and after nCRT is statistically significant 61% (95% CI: 53-70, P=0.0002). The hazard ratio (HR) of progression-free survival between ct-DNA negative and positive is significant 7.41 (95% CI: 4.87-11.289, P<0.00001). ctDNA can identify patients with different recurrence risks following nCRT and assess prognosis in patients with LARC. Further prospective study is necessary to determine the utility of ctDNA in personalised therapy for patients with LARC.

Fractional order calculus model-derived histogram metrics for assessing pathological complete response to neoadjuvant chemotherapy in locally advanced rectal cancer

AimThis study evaluates the value of diffusion fractional order calculus (FROC) model for the assessment of pathological complete response (pCR) after neoadjuvant chemoradiotherapy (nCRT) for locally advanced rectal cancer (LARC) by using histogram analysis derived from whole-tumor volumes. Materials and methodsNinety-eight patients were prospectively included. Every patient received MRI scans before and after nCRT using a 3.0-Tesla MRI machine. Parameters of the FROC model, including the anomalous diffusion coefficient (D), intravoxel diffusion heterogeneity (β), spatial parameter (μ), and the standard apparent diffusion coefficient (ADC), were calculated. Changes in median values (ΔX-median) and ratio (rΔX-median) were calculated. Receiver operating characteristic (ROC) curves were used for evaluating the diagnostic performance. ResultsPre-treatmentβ-10th percentile values were significantly lower in the pCR group compared to the non-pCR group (p < 0.001). The Δβ-median showed higher diagnostic accuracy (AUC = 0.870) and sensitivity (76.67 %) for predicting tumor response compared to MRI tumor regression grading (mrTRG) scores (AUC = 0.722; sensitivity = 90.0 %). DiscussionThe use of FROC alongside comprehensive tumor histogram analysis was found to be practical and effective in evaluating the tumor response to nCRT in LARC patients.

Comprehensive malnutritional index for predicting clinical outcomes in locally advanced rectal cancer receiving neoadjuvant chemoradiotherapy.

The objective of this investigation was to assess the prognostic significance of the comprehensive malnutritional index (CNI) in patients with locally advanced rectal cancer (LARC) who underwent neoadjuvant chemoradiotherapy (nCRT) followed by surgery. A total of 240 LARC patients were recruited. The CNI was calculated using principal components analysis based on hemoglobin (Hb), total lymphocyte count (TLC), albumin (ALB), body mass index (BMI), and usual body weight percentage (UBW%). The patients were then categorized into two groups based on the median CNI value. Cox regression and survival analyses were performed. The CNI-low (120 cases) and CNI-high (120 cases) groups were classified based on the median CNI value. The results indicated that the CNI demonstrated superior predictive ability for disease-free survival (DFS) and overall survival (OS) compared to other malnutritional indexes. LARC patients in the CNI-high group had significantly longer DFS and OS compared to those in the CNI-low group. Multivariate analysis revealed that the CNI was an independent prognostic factor for DFS (hazard ratio [HR] = 0.49; 95% confidence interval[CI], 0.29-0.83; P= 0.008) and OS (HR = 0.30; 95% CI, 0.16-0.58; P < 0.001). Additionally, the CNI-high group benefited from postoperative chemotherapy (DFS: P = 0.029, OS: P = 0.024), while the CNI-low group did not show such benefits (DFS: P = 0.448, OS: P = 0.468). These findings suggest that the CNI could serve as a valuable prognostic indicator for LARC patients who undergo nCRT followed by surgery. Preoperative nutrition optimization is important for LARC patients.

Node-sparing modified short-course Radiotherapy Combined with CAPOX and Tislelizumab for locally Advanced MSS of Middle and low rectal Cancer (mRCAT): an open-label, single-arm, prospective, multicentre clinical trial

BackgroundNeoadjuvant chemoradiotherapy followed by total mesorectal excision is a standard treatment for locally advanced rectal cancer. Mismatch repair-deficient locally advanced rectal cancer (LARC) was highly sensitive to PD-1 blockade. However, most rectal cancers are microsatellite stable (MSS) or mismatch repair-proficient (pMMR) subtypes for which PD-1 blockade is ineffective. Radiation can trigger the activation of CD8 + T cells, further enhancing the responses of MSS/pMMR rectal cancer to PD-1 blockade. Radioimmunotherapy offers a promising therapeutic modality for rectal cancer. Progenitor T exhausted cells are abundant in tumour-draining lymph nodes and play an important role in immunotherapy. Conventional irradiation fields include the mesorectum and regional lymph nodes, which might cause considerable damage to T lymphocytes and radiation-induced fibrosis, ultimately leading to a poor response to immunotherapy and rectal fibrosis. This study investigated whether node-sparing modified short-course irradiation combined with chemotherapy and PD-1 blockade could be effective in patients with MSS/ pMMR LARC.MethodsThis was a open-label, single-arm, multicentre, prospective phase II trial. 32 LARC patients with MSS/pMMR will receive node-sparing modified short-course radiotherapy (the irradiated planned target volume only included the primary tumour bed but not the tumour-draining lymph nodes, 25 Gy/5f, 5 Gy/f) followed by CAPOX and tislelizumab. CAPOX and tislelizumab will be started two days after the completion of radiotherapy: oxaliplatin 130 mg/m2 intravenous infusion, day 1; capecitabine 1000 mg/m2 oral administration, days 1–14; and tislelizumab 200 mg, intravenous infusion, day 1. There will be four 21-day cycles. TME will be performed at weeks 14–15. We will collect blood, tumour, and lymphoid specimens; perform flow cytometry and in situ multiplexed immunofluorescence detection; and analyse the changes in various lymphocyte subsets. The primary endpoint is the rate of pathological complete response. The organ preservation rate, tumour regression grade, local recurrence rate, disease-free survival, overall survival, adverse effects, and quality of life will also be analysed.DiscussionIn our research, node-sparing modified radiotherapy combined with immunotherapy probably increased the responsiveness of immunotherapy for MSS/pMMR rectal cancer patients, reduced the occurrence of postoperative rectal fibrosis, and improved survival and quality of life. This is the first clinical trial to utilize a node-sparing radiation strategy combined with chemotherapy and PD-1 blockade in the neoadjuvant treatment of rectal cancer, which may result in a breakthrough in the treatment of MSS/pMMR rectal cancer.Trial registrationThis study was registered at www.clinicaltrials.gov. Trial registration number: NCT05972655. Date of registration: 31 July 2023.

Characterization and proteomic analysis of plasma-derived small extracellular vesicles in locally advanced rectal cancer patients.

Neoadjuvant chemoradiotherapy (nCRT) stands as a pivotal therapeutic approach for locally advanced rectal cancer (LARC), yet the absence of a reliable biomarker to forecast its efficacy remains a challenge. Thus, this study aimed to assess whether the proteomic compositions of small extracellular vesicles (sEVs) might offer predictive insights into nCRT response among patients with LARC, while also delving into the proteomic alterations within sEVs post nCRT. Plasma samples were obtained from LARC patients both pre- and post-nCRT. Plasma-derived sEVs were isolated utilizing the TIO2-based method, followed by LC-MS/MS-based proteomic analysis. Subsequently, pathway enrichment analysis was performed to the Differentially Expressed Proteins (DEPs). Additionally, ROC curves were generated to evaluate the predictive potential of sEV proteins in determining nCRT response. Public databases were interrogated to identify sEV protein-associated genes that are correlated with the response to nCRT in LARC. A total of 16 patients were enrolled. Among them, 8 patients achieved a pathological complete response (good responders, GR), while the remaining 8 did not achieve a complete response (poor responders, PR). Our analysis of pretreatment plasma-derived sEVs revealed 67 significantly up-regulated DEPs and 9 significantly down-regulated DEPs. Notably, PROC (AUC: 0.922), F7 (AUC: 0.953) and AZU1 (AUC: 0.906) demonstrated high AUC values and significant differences (P value < 0.05) in discriminating between GR and PR patients. Furthermore, a signature consisting of 5 sEV protein-associated genes (S100A6, ENO1, MIF, PRDX6 and MYL6) was capable of predicting the response to nCRT, yielding an AUC of 0.621(95% CI: 0.454-0.788). Besides, this 5-sEV protein-associated gene signature enabled stratification of patients into low- and high-risk group, with the low-risk group demonstrating a longer overall survival in the testing set (P = 0.048). Moreover, our investigation identified 11 significantly up-regulated DEPs and 31 significantly down-regulated DEPs when comparing pre- and post-nCRT proteomic profiles. GO analysis unveiled enrichment in the regulation of phospholipase A2 activity. Differential expression of sEV proteins distinguishes between GR and PR patients and holds promise as predictive markers for nCRT response and prognosis in patients with LARC. Furthermore, our findings highlight substantial alterations in sEV protein composition following nCRT.

Prognostic and Predictive Value of a Modified Diagnostic Biopsy–Adapted Immunoscore in Patients with Rectal Cancer After Neoadjuvant Treatment: A Translational Study From the STELLAR Trial

BackgroundThe purpose of this study was to assess the prognostic significance of the modified diagnostic biopsy-adapted immunoscore (mISb) in determining the outcomes for patients with locally advanced rectal cancer (LARC) in a neoadjuvant setting. MethodsWe included 181 LARC patients from a single subcenter of a prospective study comparing total neoadjuvant therapy (TNT) based on short-course radiotherapy with long-term chemoradiotherapy (CRT). Tumor biopsies at baseline were stained for CD8+ and CD3+ T-cell densities. The mISb was developed using mean percentile of CD8+ T-cell density and CD8/CD3 ratios. Patients were classified into low (0%-25%), intermediate (>25%-70%), and high (>70%-100%) in both groups. The relativity among different lymphocytes and their correlation with survival were illustrated. Survival analyses and Cox regression models were used to compare the prognostic value of mISb and ISb for survival outcomes, and to assess the role of mISb in TNT and CRT subgroups respectively. ResultsIn this study, 151 (83.4%) patients received surgery and 30 (16.6%) followed a watch and wait strategy. A strong correlation was found between CD8+ and CD3+ T-cell densities (R=0.86, P<0.001), while a weak correlation witnessed between CD8+ and CD8/CD3 ratio (R=0.45). The 3-year disease-free survival (DFS) for the entire cohort was 69.9%, with 57.2%, 68.6%, and 85.5% for the low, intermediate, and high mISb groups respectively (P=0.01), while ISb failed to distinguish survival outcomes. Multivariate analysis revealed mISb to be an independent prognostic factor for DFS in surgically treated patients (P=0.01). Specifically, patients with high mISb score showed longer PFS than other subgroups in the TNT cohort (P=0.049), but no significant difference was found in the CRT population. ConclusionsIn this study, mISb demonstrates significant prognostic value in LARC patients receiving preoperative therapies, especially in the TNT subgroup. These findings may help tailor the intensity of neoadjuvant therapy for patients.

Developing Individualized Follow-Up Strategies Based on High-Risk Recurrence Factors and Dynamic Risk Assessment for Locally Advanced Rectal Cancer.

Locally advanced rectal cancer (LARC) is one of the most common malignant tumors worldwide, and its incidence is increasing year by year. Despite multimodal treatment, the recurrence rate of LARC patients remains high, about 20%-50%. However, the follow-up strategy according to tumor stage has certain limitations. There is no consensus on the optimal frequency and duration of follow-up. This study aims to comprehensively analyze the high-risk factors for recurrence in LARC from clinical characteristics, nutritional indicators, and imaging indexes. It intends to utilize conditional survival (CS) evaluation to assess dynamic survival and recurrence risks after comprehensive treatment of LARC and to develop individualized follow-up strategies. Logistic regression was utilized to analyze the independent recurrence factors in LARC patients. Calibration curve, decision curve, and ROC curve were employed to evaluate the model's efficacy. Kaplan-Meier curve was used to calculate CS rate and compare survival differences among different risk groups. A total of 561 patients were analyzed in our study. Our multivariable logistic regression analysis revealed that the prognostic nutritional index (PNI), extramural vascular invasion (EMVI), vascular tumor thrombus, perineural invasion, and tumor size were independent factors for recurrence. Subsequently, a nomogram model was constructed and risk stratification was performed. Calibration curves and decision curves demonstrated that the model exhibited good clinical efficacy. The area under the ROC curve for the model was 0.763, indicating good sensitivity and specificity. Kaplan-Meier curves showed significant differences in survival among different risk groups. Furthermore, we observed that the CS without local recurrence and distant metastasis increased each year, while the cumulative recurrence risk decreased annually with prolonged survival time. Tailored follow-up intensities were developed for different risk groups and clinical stages based on the cumulative recurrence risk. The personalized follow-up strategy based on risk stratification can optimize resource allocation, early detection of recurrence or metastasis, and ultimately enhance the overall care and prognosis of LARC patients.

Comparing robust proton versus online adaptive photon radiotherapy for short-course treatment of rectal cancer

Background and purposeImage-guided proton beam therapy (IG-PBT) and cone-beam CT (CBCT)-based online adaptive photon radiotherapy (oART) have potentials to restrict radiation toxicity. They are both hypothesised to reduce therapy limiting bowel toxicity in the multimodality treatment of locally advanced rectal cancer (LARC). This study aimed to quantify the difference in relevant dose-volume metrics for these modalities. Material and MethodsSix-degrees-of-freedom IG-PBT and oART short-course radiotherapy (SCRT) were simulated for 18 LARC patients. Relative biological effectiveness (RBE) was 1.1 for IG-PBT. Delivered dose was evaluated using post-CBCTs. Target coverage was considered robust if average dose to 99 % of the clinical target volume was ≥ 95 % of the prescription. Organ at risk (OAR) doses were compared using dose-volume histograms and severe bowel toxicity estimated using dose–response modelling. ResultsTarget coverage was robust in all patients for oART and all but one patient for IG-PBT. For the main OARs, IG-PBT increased the volume exposed to ≥ 15 Gy (RBE), but reduced volumes exposed to lower doses. Both low- and high-dose exposure to bowel loops were significantly different between the modalities (median (interquartile range) IG-PBT-V8.9Gy(RBE) = 92 cm3 (51–156), oART-V8.9Gy(RBE) = 166 cm3 (107–234), p < 0.001; IG-PBT-V23Gy(RBE) = 62 cm3 (25–106), oART-V23Gy(RBE) = 38 cm3 (18–75), p < 0.001), translating into similar total grade ≥ 3 bowel toxicity risk. ConclusionIG-PBT and oART delivered comparable and satisfying target coverage in SCRT for LARC with similar estimated risk of severe bowel toxicity. Volumes of OAR exposed to 15 Gy (RBE) or more were reduced by oART, while IG-PBT reduced the volumes receiving doses below this level.

Outcomes and failure patterns after chemoradiotherapy for locally advanced rectal cancer with positive lateral pelvic lymph nodes: a propensity score-matched analysis

PurposeThis study aimed to use propensity score matching (PSM) to explore the long-term outcomes and failure patterns in locally advanced rectal cancer (LARC) patients with positive versus negative lateral pelvic lymph node (LPLN).Materials and methodsPatients with LARC were retrospectively divided into LPLN-positive and LPLN-negative groups. Clinical characteristics were compared between the groups using the chi-square test. PSM was applied to balance these differences. Progression-free survival (PFS) and overall survival (OS), and local–regional recurrence (LRR) and distant metastasis (DM) rates were compared between the groups using the Kaplan–Meier method and log-rank tests.ResultsA total of 651 LARC patients were included, 160 (24.6%) of whom had positive LPLN and 491 (75.4%) had negative LPLN. Before PSM, the LPLN-positive group had higher rates of lower location (53.1% vs. 43.0%, P = 0.025), T4 stage (37.5% vs. 23.2%, P = 0.002), mesorectal fascia (MRF)-positive (53.9% vs. 35.4%, P < 0.001) and extramural venous invasion (EMVI)-positive (51.2% vs. 27.2%, P < 0.001) disease than the LPLN-negative group. After PSM, there were 114 patients for each group along with the balanced clinical factors, and both groups had comparable surgery, pathologic complete response (pCR), and ypN stage rates. The median follow-up was 45.9 months, 3-year OS (88.3% vs. 92.1%, P = 0.276) and LRR (5.7% vs. 2.8%, P = 0.172) rates were comparable between LPLN-positive and LPLN-negative groups. Meanwhile, despite no statistical difference, 3-year PFS (78.8% vs. 85.9%, P = 0.065) and DM (20.4% vs. 13.3%, P = 0.061) rates slightly differed between the groups. 45 patients were diagnosed with DM, 11 (39.3%) LPLN-positive and 3 (17.6%) LPLN-negative patients were diagnosed with oligometastases (P = 0.109).ConclusionsOur study indicates that for LPLN-positive patients, there is a tendency of worse PFS and DM than LPLN-negative patients, and for this group patients, large samples are needed to further confirm our conclusion.

Tumor Immune Microenvironment Biomarkers for Recurrence Prediction in Locally Advanced Rectal Cancer Patients after Neoadjuvant Chemoradiotherapy.

The tumor microenvironment (TME) has emerged as a significant prognostic factor. This study aimed to identify prognostic factors by combining clinicopathologic parameters and the TME biomarkers in patients who underwent surgery following neoadjuvant chemoradiotherapy (nCRT) for locally advanced rectal cancer (LARC). CD8+ T cells, CXCR3, CXCL10, and α-smooth muscle actin (α-SMA) were analyzed via immunohistochemical staining. We also incorporated AI-powered digital pathology to assess the spatial TME. The associations between these biomarkers, clinicopathologic parameters, and survival outcomes were evaluated. CD8+ T cell expression, CXCR3 expression in tumor-infiltrating lymphocytes (TILs), and immune phenotypes were correlated. LARC patients with a high expression of CD8+ T cells, CXCR3 in TILs, and an inflamed phenotype had a significantly better prognosis than their counterparts did. In the multivariate analysis, the expression of CD8+ T cells and the inflamed/immune-excluded phenotype were significant tumor immune microenvironment (TiME) biomarkers for recurrence-free survival (RFS) but not for overall survival (OS). Notably, patients with the immune-desert phenotype had a poor prognosis regardless of pathologic stage, even if postoperative chemotherapy was administered (p < 0.001). CD8+ T cells and AI-powered immune phenotypes, alongside clinical factors, can guide personalized treatment in LARC patients receiving nCRT. A therapeutic strategy to modify the TiME after nCRT could help reduce recurrence after surgery.

Does the initial treatment of primary tumor impact prognosis after recurrence in locally advanced rectal cancer? Results from a retrospective cohort analysis

IntroductionThe role of neoadjuvant therapy (NAT) in the treatment of locally advanced rectal cancer (LARC) has been well proven, but its impact on patients who relapse remains unknown. This study aims to elucidate the influence of initial treatment and MRI-defined risk factors on postrecurrent survival in patients with LARC recurrence.Patients and methodsLARC patients who underwent radical surgery and subsequently developed recurrence were retrospectively identified. Patients were stratified on the basis of MRI-defined local risk assessment and the initial treatment modality for the primary tumor (NAT or primary surgery). The patients were classified into four groups: high-risk LARC with NAT (HiN), high-risk LARC with primary surgery (HiS), low-risk LARC with NAT (LoN), and low-risk LARC with primary surgery (LoS). The primary endpoint was survival after recurrence.ResultsA total of 381 patients who experienced relapse were identified from among 2329 LARC patients. Salvage surgery was performed on 33.1% of these patients. Patients who experienced single-site recurrence or who underwent salvage surgery exhibited significantly prolonged survival times after recurrence (P < 0.001). Patients in the HiS group had poorer survival after recurrence than those in the other three groups (P = 0.034). This subset of patients, characterized by receiving less adjuvant treatment after primary surgery, had a shorter recurrence interval than those in the other groups (P = 0.001).ConclusionsOur findings reaffirm the prognostic significance of salvage surgery in patients from a LARC cohort who experienced relapse. Moreover, MRI-defined high-risk LARC patients who received upfront surgery without NAT had shorter intervals of recurrence and poorer survival outcomes after recurrence. Our results highlight the critical role of NAT in improving patient survival after recurrence.Trial registrationSupplementary registration was carried out at clinicaltrials.gov (Registration number: NCT06314737) on March 14, 2024. The study was retrospectively registered.

Prediction of pathological response and lymph node metastasis after neoadjuvant therapy in rectal cancer through tumor and mesorectal MRI radiomic features

Establishing predictive models for the pathological response and lymph node metastasis in locally advanced rectal cancer (LARC) treated with neoadjuvant chemoradiotherapy (nCRT) based on MRI radiomic features derived from the tumor and mesorectal compartment (MC). This study included 209 patients with LARC who underwent rectal MRI both before and after nCRT. The patients were divided into a training set (n = 146) and a test set (n = 63). Regions of interest (ROIs) for the tumor and MC were delineated on both pre- and post-nCRT MRI images. Radiomic features were extracted, and delta radiomic features were computed. The predictive endpoints were pathological complete response (pCR), pathological good response (pGR), and lymph node metastasis (LNM). Feature selection for various models involved sequentially removing features with a correlation coefficient > 0.9, and features with P-values ≥ 0.05 in univariate analysis, followed by LASSO regression on the remaining features. Logistic regression models were developed, and their performance was evaluated using the area under the receiver operating characteristic curve (AUC). Among the 209 LARC patients, the number of patients achieving pCR, pGR, and LNM were 44, 118, and 40, respectively. The optimal model for predicting each endpoint is the combined model that incorporates pre- and delta-radiomics features for both the tumor and MC. These models exhibited superior performance with AUC values of 0.874 (for pCR), 0.801 (for pGR), and 0.826 (for LNM), outperforming the MRI tumor regression grade (mrTRG) which yielded AUC values of 0.800, 0.715, and 0.603, respectively. The results demonstrate the potential utility of the tumor and MC radiomics features, in predicting treatment efficacy among LARC patients undergoing nCRT.

Barriers to Offering Organ Preservation for Rectal Cancer in a Predominantly Hispanic Safety Net Hospital.

Total neoadjuvant therapy (TNT) for locally advanced rectal cancer (LARC) has shown promise in achieving pathologic complete response (pCR) and enabling organ preservation through watch-and-wait (WW) strategies. However, implementation of WW protocols in diverse patient populations and safety-net hospitals faces unique challenges. The objective of this study is to evaluate TNT outcomes and identify barriers to WW implementation in a predominantly Hispanic safety-net hospital in South Texas. A retrospective review was conducted of 40 LARC patients treated with TNT at an academic tertiary referral center in South Texas between 2018 and 2023. Patient demographics, disease characteristics, and pCR rates were analyzed. A survey of multidisciplinary providers assessed perceived institutional and patient-related barriers to WW implementation. The cohort was 70% Hispanic, with a median age of 54 years. Most patients had advanced disease at diagnosis (57.5% T4, 65% N2). The pCR rate was 18.5% (5/27) among patients undergoing surgery. Re-review of MRIs for pCR patients revealed that 2/5 had minimal residual disease. The provider survey identified MRI quality variability, lack of dedicated treatment coordinators, and concerns about patient compliance and financial barriers as key obstacles to WW implementation. Despite advanced disease presentation in a predominantly Hispanic population, TNT achieved pCR rates comparable to international trials. Institutional and patient-level barriers to WW were identified, informing the development of a tailored WW protocol for this unique patient population.

Predictive value of mono-exponential and multiple mathematical models in locally advanced rectal cancer response to neoadjuvant chemoradiotherapy.

This prospective study aimed to assess the predictive value of mono-exponential and multiple mathematical diffusion-weighted imaging (DWI) models in determining the response to neoadjuvant chemoradiotherapy (nCRT) in patients with locally advanced rectal cancer (LARC). The study included 103 LARC patients scheduled for preoperative chemoradiotherapy between December 2021 and June 2023 Magnetic resonance imaging (MRI) scans were performed using a 3.0-T MR scanner, encompassing sagittal, axial, and oblique coronal T2-weighted images without fat saturation, along with DWI perpendicular to the rectum's long axis. Various DWI parameters, including apparent diffusion coefficient (ADC), stretched exponential model (SEM), continuous-time random-walk model (CTRW), and fractional-order calculus model (FROC), were measured. The pathologic complete response (pCR) rate and tumor downstaging (T-downstage) rate were determined. After nCRT, SEM-α, SEM-DDC, CTRW-α, CTRW-β, CTRW-D, FROC-β, and ADC values were significantly higher in the pCR group compared to the non-pCR group (all P < 0.05). SEM-DDC, CTRW-α, CTRW-D, FROC-β, FROC-µ, and ADC values were significantly higher in the T-downstage group (ypT0-1) than in the non-T-downstage group (ypT2-4) (P < 0.05). The combination of CTRW (α + β + D) exhibited the best diagnostic performance for assessing pCR after nCRT (AUC = 0.840, P < 0.001). Pre-nCRT CTRW (α + β) demonstrated a predictive AUC of 0.652 (95%CI: 0.552-0.743), 90.3% sensitivity, and 43.1% specificity for pCR. Regarding T-downstage assessment after nCRT, the combination of CTRW (α + D) yielded the best diagnostic performance (AUC = 0.877, P = 0.048). In LARC patients, imaging markers derived from CTRW show promise in predicting tumor response before nCRT and assessing pCR after nCRT.

SP5.10 - Statin use during neoadjuvant therapy is an independent marker for a favourable Neoadjuvant Rectal (NAR) score in locally advanced rectal cancer when analysing common concomitant medications

Abstract Aim The extent of neoadjuvant therapy (NAT) response is an important prognosticator in locally advanced rectal cancer (LARC). The Neoadjuvant Rectal (NAR) is validated as a pseudo-continuous measurement of response, and a surrogate marker of long-term outcomes. We investigated the impact of common concomitant medications (statins, antiplatelets, metformin) on the extent of response using the NAR score. Methods A retrospective review of regional cancer centre LARC patients undergoing NAT was performed between June 2016 - 2021. The NAR score was calculated as previously described by George et al (2015). Results 253 patients were included. 104(34%), 52(17%), and 19(6%) patients took statins, antiplatelets, and metformin respectively. 90% of those on an antiplatelet are also on a statin. Of those on statins, 45.2% and 14.4% also took antiplatelets or metformin respectively. There was no significant association with concomitant medication use and disease stage or tumour size. Only metformin use associated with the absence of Extramural vascular invasion (EMVI) (p=0.031) on pre-NAT MRI. Neither antiplatelets nor metformin use associated with the extent of NAT response. Statin use associated with a favourable NAR score (p=0.008). On multivariate analysis with pre-NAT mrEMVI and nodal status, concomitant statin use independently predicted a favourable NAR score of &amp;lt;16 (OR 2.019, 95%CI 1.11-3.67, p=0.021). Conclusion Concomitant statin use at time of neoadjuvant therapy associates with a favourable response. Antiplatelet and metformin use does not appear to influence response. Analysis through a clinical trial of statin use combined with neoadjuvant therapy may give more insight into how it influences response.

Predictive and prognostic value of preoperative pan-immune-inflammation value in patients with locally advanced rectal cancer.

This study aimed to investigate the prognostic value of the pan-immune-inflammation value (PIV) in patients with locally advanced rectal cancer (LARC) who received neoadjuvant chemoradiotherapy (nCRT) followed by total mesorectal excision. We retrospectively collected and analyzed the clinicopathological data of 215 resected LARC patients. X-tile software was used to determine the optimal threshold value for PIV in predicting overall survival (OS). The predictive ability of PIV for pathological complete regression (pCR), OS, and disease-free survival (DFS) was evaluated and compared with other inflammation markers. Univariate and multivariate logistic regression analyses for pCR and Cox regression analyses for OS and DFS were conducted. Theoptimal threshold value for PIV was determined to be 454.7 based on the X-tile software. Patients were then categorized into low (≤ 454.7) and high (> 454.7) PIV groups comprising 153 and 62 patients, respectively. PIV demonstrated superior predictive ability for pCR, OS, and DFS compared to other inflammation markers. LARC patients with low PIV had significantly higher pCR (P = 0.029), OS (P = 0.002), and DFS (P = 0.001) rates compared to those with high PIV. Multivariate regression analysis identified PIVas an independent prognostic factor for pCR (odds ratio = 0.32; 95% confidence interval [CI], 0.10-0.80; P = 0.014), OS (hazard ratio = 3.08; 95% CI, 1.77-5.35; P = 0.001), and DFS (hazard ratio = 2.53; 95% CI, 1.58-4.06; P = 0.002). Thisstudy confirmed thatpreoperativePIVcould serve asa useful independent prognostic factor in LARC patients treated with nCRT.

Post-hoc analysis of clinicopathological factors affecting lateral lymph node metastasis based on STELLAR study for rectal cancer

PurposeIn post-hoc analyses of phaseIII randomized controlled study(STELLAR), to analyzethe prognostic impact oflateral pelvic lymph node (LPLN)metastasis in locally advanced rectal cancer (LARC). MethodsLPLN metastasis was defined as a short diameter > 7 mm on magnetic resonance imaging (MRI).The studyincluded 591 patients with LARC.All patients received neoadjuvant (chemo)radiotherapy combined withradical resection. ResultsAmong 591 patients, 99 (16.8 %) were diagnosed with LPLN metastasis, mostly with unilateral metastasis (79.8 %), with internal iliac lymph node metastasis being more common (81.8 %).Significant differences were found among with and without LPLN metastasis in rectal segmentation (P=0.001),N disease (P<0.001), mesenteric LN metastasis or not (P=0.030). The median follow-up timewas 34.0 months, three-year disease-free survival (DFS),overall survival (OS), andmetastasis-free survival (MFS)were significantly lower in LPLN metastaticgroup than those in LPLN non-metastaticgroup (51.4 % vs. 68.2 %, P<0.001; 71.8 % vs. 84.2 %, P=0.006; 60.8 % vs. 80.1 %,P<0.001), respectively; while there were no significant differences in locoregional recurrence(11.4 % vs. 8.5 %, P=0.564). Multivariate analysis found that LPLN metastasis was an independent prognostic factor affecting DFS (P=0.005), OS (P=0.036),MFS (P=0.001).No significantly survival benefit was observed for the short-term radiotherapy based total neoadjuvant therapy compared to long-term concurrent chemoradiotherapy. ConclusionsLPLN metastasis observed byMRI should be considered in LARC patients, especially in populations with lowrectal cancer, N2 disease, and mesenteric LN metastasis. LPLN metastasis diagnosed by MRI is a significant and independent risk factor and is associated with worse DFS, OS, MFS.

Circulating tumor DNA for predicting radiographic and pathologic response to total neoadjuvant therapy in locally advanced rectal cancer: ENSEMBLE-1.

71 Background: Total neoadjuvant therapy (TNT) has dramatically shifted the treatment paradigm for locally advanced rectal cancer (LARC), prolonging survival with high rates of pathologic complete response (pCR) and introducing opportunities for nonoperative management (NOM). However, there is a need for robust predictive biomarkers of TNT efficacy, local cancer regrowth in NOM, and overall prognosis. Circulating tumor DNA (ctDNA) is a minimally invasive biomarker used to detect molecular residual disease (MRD) and predict recurrence in colorectal cancer after curative resection. The effectiveness of ctDNA MRD status specifically as a predictive biomarker for TNT was evaluated in the Phase II TNT study, ENSEMBLE-1 (jRCTs051200113), conducted in Japan. Methods: Patients with LARC undergoing TNT were enrolled in ENSEMBLE-1. Protocol treatment was defined as short-course radiotherapy (SCRT: 25Gy) followed by six cycles of CAPOX and total mesorectal excision (TME). NOM was allowed if a clinical complete response (cCR) was achieved after TNT. ctDNA was measured by SignateraTM (Natera, Inc.) at the following time points: baseline (pre-treatment), after SCRT, after 4 cycles of CAPOX, before TME, and post operatively at 4w, 12w, 24, 36 and 48w in the GALAXY trial (UMIN000039205). Results: A total of 30 patients were enrolled in the study. After completing TNT, TME and NOM were performed in 20 and 7 patients, respectively. ctDNA was measured in 26 patients (TME: 19 patients, NOM: 7 patients). ctDNA was detected in 100% (25/25) at baseline, 81% (21/26) after SCRT, 31% (8/26) after 4 cycles of CAPOX, and 45% (9/20) after TNT. The attached table shows the results of statistical analyses of the correlation between ctDNA status, clinical response, TME or NOM, and pathologic complete response (pCR). It was found that ctDNA status after SCRT and after 4 cycles of CAPOX was associated with cCR or non cCR (p=0.007 and p=0.007, respectively). Additionally, ctDNA status after TNT was associated with pCR or non pCR (p=0.029). Conclusions: Our study demonstrates that ctDNA-based MRD may predict TNT response in LARC patients. Negative ctDNA during treatment correlates with favorable responses and may be an aid in NOM decision making. Clinical trial information: jRCTs051200113 . [Table: see text]

Factors associated with pathological complete remission after neoadjuvant chemoradiotherapy in locally advanced rectal cancer: a real-world clinical setting.

This study aims to identify factors associated with achieving a pathological complete remission (pCR) in patients with locally advanced rectal cancer (LARC) after neoadjuvant chemoradiotherapy (nCRT). We conducted a cohort analysis of 171 LARC patients who underwent curative resection post-nCRT at the First Affiliated Hospital of Guangxi Medical University between January 2015 and December 2021. The data encompassed clinical and pathological information. Univariate and binary logistic regression multivariate analyses were employed to examine the factors influencing pCR achievement after nCRT. Kappa value tests were utilized to compare clinical staging after nCRT with postoperative pathological staging. Postoperative histopathology revealed that of the 171 patients, 40 (23.4%) achieved TRG 0 grade (pCR group), while 131 (76.6%) did not achieve pCR, comprising 36 TRG1, 42 TRG2, and 53 TRG3 cases. Univariate analysis indicated that younger age (p=0.008), reduced tumor occupation of intestinal circumference (p =0.008), specific pathological types (p=0.011), and lower pre-nCRT CEA levels (p=0.003) correlated with pCR attainment. Multivariate analysis identified these factors as independent predictors of pCR: younger age (OR=0.946, p=0.004), smaller tumor occupation of intestinal circumference (OR=2.809, p=0.046), non-mucinous adenocarcinoma pathological type (OR=10.405, p=0.029), and lower pre-nCRT serum CEA levels (OR=2.463, p=0.031). Clinical re-staging post-nCRT compared to postoperative pathological staging showed inconsistent MRI T staging (Kappa=0.012, p=0.718, consistency rate: 35.1%) and marginally consistent MRI N staging (Kappa=0.205, p=0.001, consistency rate: 59.6%). LARC patients with younger age, presenting with smaller tumor circumferences in the intestinal lumen, lower pre-nCRT serum CEA levels, and non-mucinous adenocarcinoma are more likely to achieve pCR after nCRT. The study highlights the need for improved accuracy in clinical re-staging assessments after nCRT in LARC.

Efficacy and safety of combining short-course neoadjuvant chemoradiotherapy with envafolimab in locally advanced rectal cancer patients with microsatellite stability: A phase II PRECAM experimental study.

Conventional neoadjuvant chemoradiotherapy (nCRT) yields a pathologic complete response (pCR) rate of 15%-30% for locally advanced rectal cancer (LARC). This study ventures to shift this paradigm by incorporating short-course nCRT with immunotherapy, specifically Envafolimab, to achieve improved treatment efficacy and possibly redefine the standard of care for LARC. The PRECAM study is a prospective, single-arm, phase 2 clinical trial for LARC in patients with microsatellite stable (MSS) tumors. Participants received short-course radiotherapy (25Gy/5f), followed by two cycles of CAPEOX chemotherapy and six weekly doses of Envafolimab, a PD-L1 antibody, before total mesorectal excision surgery. The primary endpoint was the pCR rate. From April to December 2022, 34 patients were enrolled, of whom 32 completed the study, each diagnosed with an MSS rectal adenocarcinoma. All patients underwent preoperative CRT combined with Envafolimab. Remarkably, a pCR rate of 62.5% (20/32) was attained, and a significant pathologic response rate of 75% (24/32) was achieved. Additionally, 21 of 32 participants achieved a neoadjuvant rectal (NAR) score below 8, suggesting an effective treatment response. Common adverse events included tenesmus (78.1%), diarrhea (62.5%), and leukocyte decrease (40.6%). Two Grade 3 adverse events were noted, one related to liver function abnormality and the other to a decrease in platelet count. Surgical procedures were performed in all cases, with minor complications, including ileus, infections, and anastomotic leakage. As of this report, there have been no reported cases of recurrence or death during the follow-up period, ranging from 12 to 20 months. In LARC patients exhibiting MSS tumors, combining short-course nCRT with Envafolimab demonstrated favorable efficacy, leading to a significant pCR rate. Minor adverse effects and surgical complications were observed. These preliminary but promising results underscore the potential of this approach and call for further exploration and validation through a randomized controlled trial.