Low Rectal Cancer Research Articles

Saturday, July 13, 20248:00 AM - 9:00 AMMSOR01 Presentation Time: 8:00 AM: Papillon Brachytherapy and External Beam Radiotherapy in Low Rectal Cancer Patients: An Insight on Side Effect Comparisons

Saturday, July 13, 20248:00 AM - 9:00 AMMSOR01 Presentation Time: 8:00 AM: Papillon Brachytherapy and External Beam Radiotherapy in Low Rectal Cancer Patients: An Insight on Side Effect Comparisons

Predictive factors for pathological complete response to neoadjuvant therapy in locally advanced rectal cancer: a review of current research

The guidelines advocate for preoperative neoadjuvant radiotherapy and chemotherapy in cases of middle and low locally advanced rectal cancer. While some patients achieved pathological complete response (pCR), which is favorable and allows for potential organ preservation, treatment sensitivity varies and not all patients reach pCR. Identifying the factors influencing pCR is important for enhancing the effectiveness of neoadjuvant therapy and improving patient outcomes. Previous research has identified various factors associated with response to neoadjuvant therapy, which can serve as predictors of pCR. This study reviews recent literature on imaging, pathological, genetic, and molecular characteristics, laboratory indices, and therapeutic factors related to tumor response, both domestically and internationally. The aim is to summarize the latest advancements in understanding the factors associated with pCR in patients with locally advanced middle and low rectal cancer undergoing neoadjuvant therapy, thereby providing a theoretical foundation for standardized clinical treatment approaches.

A study of intersphincteric resection rate following robotic-assisted total mesorectal excision versus laparoscopic-assisted total mesorectal excision for patients with middle and low rectal cancer: study protocol for a multicenter randomized clinical trial

IntroductionRobotic-assisted complete mesorectal excision (RATME) is increasingly being used by colorectal surgeons. Most surgeons consider RATME a safe method, and believe it can facilitate total mesorectal excision (TME) in rectal cancer, and may potentially have advantages over intersphincteric resection (ISR) and anus preservation. Therefore, this trial was designed to investigate whether RATME has technical advantages and can increase the ISR rate compared with laparoscopic-assisted TME (LATME) in patients with middle and low rectal cancer.Methods and analysisThis is a multicenter, superiority, randomized controlled trial designed to compare RATME and LATME in middle and low rectal cancer. The primary endpoint is the ISR rate. The secondary endpoints are coloanal anastomosis (CAA) rate, conversion to open surgery, conversion to transanal TME (TaTME), abdominoperineal resection (APR) rate, postoperative morbidity and mortality within 30 days, pathological outcomes, long-term survival outcomes, functional outcomes, and quality of life. In addition, certain measurements will be conducted to ensure quality and safety, including centralized photography review and semiannual assessment.DiscussionThis trial will clarify if RATME improves ISR and promotes anus preservation in patients with mid- and low-rectal cancer. Furthermore, this trial will provide evidence on the optimal treatment strategies for RATME and LATME in patients with mid- and low-rectal cancer regarding improved operational safety.Trial registrationClinicalTrials.gov NCT06105203. Registered on October 27, 2023.

Prognostic impact of lateral sentinel lymph node biopsy using indocyanine green on oncological outcomes for clinical stage II/III lower rectal cancer without suspected lateral lymph node metastasis.

Sentinel lymph node biopsy (SLNB) can detect occult nodal metastasis. We have previously reported the safety and feasibility of indocyanine green (ICG)-guided SLNB for clinical stage II/III lower rectal cancer (RC). However, little is known about the influence of lateral pelvic SLNB using ICG on oncological outcomes. The present study aimed to evaluate the prognostic impact of lateral pelvic SLNB on oncological outcomes compared with prophylactic lateral lymph node dissection (LLND). Participants comprised consecutive patients with clinical stage II/III lower RC who underwent lateral pelvic SLNB or prophylactic LLND (Non-SLNB) between January 2010 and December 2020. The primary outcome measure was the 5-year cumulative incidence of local recurrence (LR). Secondary endpoints included cancer-specific survival (CSS), overall survival (OS), recurrence-free survival (RFS), local recurrence-free survival (LRFS), and distant recurrence-free survival (DRFS). Among the 150 eligible patients included, 79 patients underwent lateral pelvic SLNB. Of those 79 patients, 4 patients who were SLNB-positive underwent LLND. LLND was omitted for the 75 patients who were SLNB-negative. Median follow-up was 61.0 months (range, 1.3-143.2 months). The overall recurrence rate was 30.7% (46 patients), with LR in 12.0% (18 patients). LR comprised lateral lymph node recurrence in 2.6% and central pelvic recurrence in 9.4%. No significant differences were seen between groups in terms of the frequency of LR or in CSS, OS, RFS, LRFS, or DRFS. Oncological outcomes were not different between the SLNB and Non-SLNB groups. ICG-guided SLNB appears promising as a method for determining indications for LLND.

Lateral node metastasis in low rectal cancer as a hallmark to predict recurrence patterns.

Lateral node metastasis confers a poor prognosis in rectal cancer. Several multidisciplinary treatments have been proposed with favorable outcomes. However, appropriate neoadjuvant/adjuvant treatments or follow-up plans based on information about the probable recurrence site have not been specified. We aimed to clarify the distinctive features of recurrence patterns for lateral node-positive low rectal cancer according to the lateral and mesorectal lymph node status. We retrospectively analyzed 508 patients with stage III low rectal cancer who underwent lateral node dissection. We investigated the impact of lateral and mesorectal lymph node status on site-specific recurrence rates and patient survival. Analyses for relapse-free survival revealed the prognostic impact of lateral node positivity in stage III low rectal cancer (p < 0.0001). Lateral node-positive patients exhibited higher risk of overall recurrence, local recurrence, and recurrence in extra-regional nodes than lateral node-negative patients (p < 0.0001, p = 0.001, and p < 0.0001, respectively). However, lateral node positivity was not statistically associated with a hematogenous recurrence rate. In lateral node-positive patients, both tumor-node-metastasis (TNM)-N status and number of lateral nodes involved were revealed as significant prognostic factors (p < 0.0001, both). In addition, the number of lateral nodes involved could be a discriminatory indicator of probabilities of local recurrence and recurrence in extra-regional nodes (p = 0.02, and p < 0.0001, respectively). Lateral node-positive low rectal cancer exhibits higher local recurrence and extra-regional node recurrence rates that correlate with the number of lateral nodes involved.

First in human intraarterial delivery of tislelizumab for the treatment of pMMR locally advanced rectal cancer: A single-arm, open label, phase II clinical trial

BackgroundIntravenous immune checkpoint inhibitors (ICIs) have shown efficacy in treating locally advanced rectal cancer (LARC), but concerns about systemic toxicity persist. This study developed a unique approach termed chemo-immuno-embolization with transcatheter rectal arterial intervention (CIETAI), aiming to enhance the anti-tumor response while minimizing systemic toxicity. MethodThis is a prospective, single-arm, phase II clinical trial conducted in Daping hospital. Patients with previously untreated stage II/III LARC underwent preoperative CIETAI combined with PD-1 inhibitor tislelizumab plus oxaliplatin, followed by standard concomitant chemoradiotherapy (capecitabine and 50.4 Gy radiation). Intravenous tislelizumab was administered for an additional two cycles. ResultsBetween January 2023 and December 2023, a total of 38 patients were enrolled. As the primary endpoint, 17 (44.74 %) patients achieved pathological complete response (TRG0), with a major pathologic response (MPR) rate of 65.79 %. The anal preservation rate was 84.21 % (32/38), and importantly, 15 of 21 patients with low rectal cancer achieved organ preservation with functional maintenance. Eight patients experienced grade 3–4 adverse events (AEs). All immune-related AEs were grade 1–2, with the most common being endocrine toxicity (5/6, 83.33 %). No grade 5 AEs occurred. ConclusionThis study provides preliminary evidence supporting the safety and efficacy of intraarterial tislelizumab delivery in the neoadjuvant setting for LARC. These promising results encourage further exploration in larger cohorts to validate the clinical impact of this novel CIETAI strategy. Trial registrationClinicalTrials.gov Identifier: NCT05957016.

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.

Transperineal minimally invasive surgery during laparoscopic abdominoperineal resection for low rectal cancer could improve short-term outcomes: A single-institution retrospective cohort study.

Transperineal minimally invasive surgery (TpMIS) during laparoscopic abdominoperineal resection (APR) is an emerging approach that allows for the precise treatment of lower rectal cancer. However, evidence regarding the efficacy of TpMIS is insufficient. This study evaluated the efficacy of TpMIS during laparoscopic APR for patients with lower rectal cancer. Patients who underwent laparoscopic APR with TpMIS (TpMIS group; n = 12) and those who underwent conventional laparoscopic APR for low rectal cancer (conventional group; n = 13) were enrolled consecutively in this retrospective study. Standardized TpMIS was performed at our institution. Patient and tumor characteristics and intraoperative, postoperative, and pathological outcomes were compared between groups. The primary outcome was postoperative perineal wound infection. No patients in the TpMIS group experienced postoperative perineal wound infection; however, five (38.5%) patients in the conventional group experienced postoperative perineal wound infection (significant difference; p = 0.016). The estimated blood loss (median, 81mL vs. 463mL) and incidence of postoperative urinary dysfunction (8.3% vs. 46.1%) were significantly lower in the TpMIS group than in the conventional group. The postoperative hospital stay (median, 13 vs. 20days) of the TpMIS group was significantly shorter than that of the conventional group. Pathological outcomes did not differ between groups. The positive circumferential resection margin rates of the TpMIS and conventional groups were 8.3% and 15.4%, respectively. TpMIS during laparoscopic APR was associated with significant improvements in the postoperative outcomes of patients with low rectal cancer.

A New Approach to Ultra-Low Anterior Resection-Intersphincteric Dissection With Total Hiatal Ligament Excision for Very Low Rectal Cancer Located in the Posterior Wall of the Rectum: A More Satisfactory Technique for Local Recurrence Control.

The hiatal ligament, as the anatomical landmark for the completion of total mesorectal excision (TME) for ultra-low rectal cancer, represents a continuation of the longitudinal muscle of the rectum. It receives vascular supply from the median sacral artery and contains lymphatic vessels. In cases where ultra-low rectal cancer is located in the posterior rectal wall, the hiatal ligament may theoretically serve as an anatomical region susceptible to direct tumor cell spread or distant metastasis. To evaluate the effect of circumferential tumor location (CTL) on postoperative survival of low rectal cancer and to determine the effect of total hiatal ligament excision (THLE) on the prognosis of patients with posterior rectal cancer. Patients with ultra-low rectal cancer who underwent laparoscopic surgery between March 2014 and October 2021 were enrolled in this study. Propensity score matching (PSM) analysis was used to compare the clinicopathological characteristics and prognosis of patients in the posterior group and the non-posterior group. Prognostic factors were identified using COX regression. PSM analysis was also used in the posterior tumor subgroup to compare the clinicopathological characteristics and prognosis of patients in the hiatal ligament traditional transection (HLTT) and THLE groups. After PSM, OS, and DFS were comparable between the posterior and non-posterior groups. Similarly, no difference was noted in the local recurrence rate between the two groups (p = 0.23). The prognosis of ultra-low rectal cancer was not affected by CTL. However, the local recurrence rate was significantly lower in the THLE group compared with the HLTT group (p = 0.023). Multivariate analysis of the posterior group identified CRM, TNM stage III, and HLTT as independent risk factors for local recurrence-free survival. CTL is not a prognostic risk factor for low rectal cancer. In posterior wall tumors, THLE significantly reduces the local recurrence rate for low rectal cancer.

A prospective observational study on functional outcomes and condition-specific quality of life after intersphincteric resection for low rectal cancer

Objective: To investigate functional outcomes and condition-specific quality-of-life (CSQoL) after intersphincteric resection (ISR) in patients with low rectal cancer using traditional and exploratory questionnaires. Methods: A prospective observational study was conducted in the Characteristic Medical Center of the People's Liberation Army Rocket Force. Patients with low rectal cancer who underwent ISR with ileostomy reversal from May 2020 to April 2023 were enrolled. An electronic self-assessment survey was sent to enrolled patients at 3 to 6, 12, and 24 to 36 months after reversal, and differences in functional and CSQoL results between the 3 groups were analyzed with generalized estimation equations. Functional outcomes were determined by the Wexner incontinence score (WIS) and the low anterior resection syndrome (LARS) score. In line with the five frequency responses ranging from never (score 0) to always (score 4) defined by the WIS, an exploratory survey was used to measure the severity of 16 LARS-specific variables confirmed by the latest international Delphi consensus. Furthermore, CSQoL was evaluated using the fecal incontinence quality-of-life scale (FIQL) and the visual analog scale (VAS). Results: A total of 90 patients were enrolled in the study. There were 64 males and 26 females, aged (58.6±10.4) years (range: 28 to 79 years). The median distance from the distal tumor margin to the anal verge(M(IQR)) was 3.0 (1.5) cm (range: 1.0 to 5.0 cm). There were 55 patients who completed the questionnaires at 3 to 6 months, 59 patients at 12 months, and 40 patients at 24 to 36 months of follow-up, respectively. The summary score of FIQL and VAS improved significantly after reversal (2.33±0.69 vs. 2.40±0.66 vs. 2.79±0.76, χ2=11.703,P=0.003; 5.31±1.65 vs. 5.61±1.90 vs. 6.58±1.92, χ2=12.781,P=0.002), but the differences in the WIS and LARS score did not reach statistical significance (both P>0.05). The survey responses for the LARS-specific variables indicated that "emptying difficulties" and "dissatisfaction with the bowels" were the most frequent symptom and consequence after ISR, respectively. The exploratory severity score for LARS improved significantly among the 3 time periods(34 (14) vs. 31 (13) vs. 23 (17), χ2=13.952,P=0.001). Furthermore, the FIQL summary score was strongly correlated with the LARS severity score (rs=-0.72, P<0.01). Conclusions: Although a high prevalence of LARS may persist for years, patients reported an improvement in CSQoL and functional outcomes after ISR. The highest priorities recommended by the international consensus might provide better assessments the severity of LARS.

Oncological and functional outcomes of sphincter saving procedures versus abdominoperineal resection for low rectal cancer: A comparative prospective cohort study.

Oncological and functional outcomes of sphincter saving procedures versus abdominoperineal resection for low rectal cancer: A comparative prospective cohort study.

Tolerability and Safety Assessment of Adjuvant Chemoradiotherapy with S-1 after Limited Surgery for T1 or T2 Lower Rectal Cancer

Background: The short-term outcomes of chemoradiotherapy (CRT) with S-1 (a combination of tegafur, gimeracil, and oteracil) following limited surgery for patients with T1 or T2 lower rectal cancer have shown encouraging results. Objectives: This study was designed to delve deeper into the long-term outcomes of CRT with S-1 after limited surgery, with the goal of evaluating both the long-term efficacy and potential risks associated with this treatment approach in patients diagnosed with T1 or T2 lower rectal cancer. Methods: This was conducted as a multicenter, single-arm, prospective phase II trial. The patient population consisted of individuals clinically diagnosed with either T1 or T2 lower rectal or anal canal cancer, with a maximum tumor diameter of 30 mm and classified as N0 or M0. Patients underwent local excision or endoscopic resection. After surgery, CRT with S-1 was administered to patients meeting several criteria, including the confirmation of well-differentiated or moderately differentiated adenocarcinoma, negative surgical margins, submucosal invasion depth of ≥1000 µm, and high tumor-budding grade (2/3). The primary endpoint of this study was relapse-free survival, while secondary endpoints included local recurrence-free survival, overall survival, anal sphincter preservation rate, and safety. Results: A total of 52 patients were included, with pathological diagnoses revealing T1 in 36 patients and T2 in 16 patients. The 3-year and 5-year relapse-free survival rates were 90.17% and 85.87%, respectively. The 3-year and 5-year local recurrence-free survival rates were 90.17% and 88.07%, respectively, while the 3-year and 5-year overall survival rates were 94.03% and 91.94%, respectively. Conclusions: CRT with S-1 after limited surgery for T1 lower rectal cancer demonstrated favorable outcomes in terms of recurrence, survival, and local control rates while effectively maintaining anal function in patients. However, further treatment approaches may be necessary to improve outcomes for patients diagnosed with stage T2 lower rectal cancer

Deep pelvis and low visceral fat mass as risk factors for neurogenic bladder after rectal cancer surgery

BackgroundPostoperative neurogenic bladder (PONB) frequently occurs as a complication after rectal cancer surgery. This study aimed to analyze risk factors for developing PONB after rectal cancer surgery, particularly the association between pelvic anatomy and visceral fat mass.MethodsWe included 138 patients who underwent rectal resection for lower rectal cancer in our department between 2017 and 2021. PONB was defined as the need for urethral catheter reinsertion or oral medication administration for urinary retention after catheter removal with severe NB that required treatment for ≥ 60 days. We obtained visceral fat area (VFA) at the umbilical level based on a CT scan and measured five pelvic dimensions.ResultsOf the 138 patients, 19 developed PONB, with 16 being severe cases. PONB more frequently occurs in patients with a height of < 158 cm, age ≥ 70 years, surgery lasting ≥ 8 h, intraoperative bleeding volume ≥ 150 mL, lateral lymph node dissection, and narrower pelvis. It was more prevalent in cases with low VFA. Conversely, gender, body mass index (BMI), and medical history showed no significant correlations. Multivariate analysis revealed older age, prolonged surgery, and low VFA as independent risk factors for PONB. Independent risk factors for severe PONB included low VFA, older age, prolonged surgery, and deep pelvis.ConclusionLower VFA, older age, and prolonged surgery are independent risk factors for developing PONB. Additionally, a deep pelvis is an independent risk factor for severe PONB. Delicate surgical techniques should consider the risk of nerve injury in cases with low VFA and deep pelvis.

Efficacy and long-term outcomes of abdominoperineal resection using transperineal total mesorectal excision approach for rectal cancer.

Although abdominoperineal resection (APR) is essential for a certain population of patients with low rectal cancer, it is technically difficult and sometimes contains oncological disadvantages. Thus, the use of the transperineal total mesorectal excision (TpTME) approach might overcome such concerns regarding APR. In total, 27 patients who underwent conventional APR (conventional group) and 49 patients who underwent APR using the TpTME approach (TpTME group) for low rectal cancer were included. After propensity score matching, the outcomes of the 25 matched cases were compared between groups. The operative time was significantly shorter in the TpTME group than in the conventional group (452 vs. 565min, P = 0.039). Intraoperative blood loss and transfusion rates were also significantly lower in the TpTME group than in the conventional group (25mL vs. 200mL, P < 0.001 and 0% vs. 28.0%, P = 0.015, respectively). Although the incidence of postoperative complications did not differ significantly, the postoperative hospital stay was significantly shorter in the TpTME group than in the conventional group (24 vs. 36days, P = 0.001). The 5year relapse-free survival rates in the TpTME and conventional groups were 62.0% and 57.6%, respectively (P = 0.648). APR using the TpTME approach for the treatment of low rectal cancer is feasible and can achieve favorable oncological outcomes.

Application of modified extralevator abdominoperineal excision for low rectal cancer resection.

Laparoscopic ELAPE surgery has been carried out in our center for a long time, and some modifications have been made in clinical practice. In this study, we compared conventional ELAPE operation with modified ELAPE operation to investigate the efficacy and safety of modified ELAPE operation. We retrospectively analyzed the data from 339 patients with low rectal cancer undergoing abdominoperineal resection from 2017 to 2021 in the Department of General Surgery, Qilu Hospital of Shandong University. Patients were classified into modified ELAPE groups (199 patients) and conventional ELAPE groups (140 patients). Total operation time, reconstruction time, postoperative hospital stay, total cost, intraoperative data, postoperative short-term and long-term complications and tumor recurrence were compared. The baseline characteristics were comparable between the two groups. Total operation time was less with modified ELAPE group compared to conventional ELAPE group (190.6 ± 33.1min vs 230.1 ± 51.6min, P = 0.022). Pelvic floor reconstruction time was also less with modified ELAPE group compared to conventional ELAPE group (4.3 ± 1.2min vs 11.9 ± 1.7min, P = 0.004). Positive CRM was observed in 11 and 9 patients in modified ELAPE groups and conventional ELAPE groups (P = 0.744). IOP occurred in 12 and 7 patients in modified ELAPE group and conventional ELAPE group (P = 0.701). Total cost was also less with modified ELAPE group compared to conventional ELAPE group (9004 ± 1146 USD vs 10,336 ± 2047 USD, P = 0.031). The incidence of parastomal hernia was less with modified ELAPE group compared to conventional ELAPE group (7/199 vs 22/140, P < 0.001). Three-year follow-up data did not show any difference in overall survival rate or local occurrence between the two groups. Modified ELAPE surgery is technically safe and feasible, and oncologically comparable to that of conventional ELAPE surgery, which can be considered for popularization and application.

Neoadjuvant Immunotherapy Alone for Patients With Locally Advanced and Resectable Metastatic Colorectal Cancer of dMMR/MSI-H Status.

The use of programmed death-1 blockade has a significant therapeutic effect in patients with mismatch repair-deficient/microsatellite instability-high metastatic colorectal cancer. However, data on preoperative single-agent programmed death-1 blockade are rare. This study aims to evaluate the effectiveness and safety of preoperative programmed death-1 blockade as a conversion strategy in patients with locally advanced and resectable metastatic mismatch repair-deficient/microsatellite instability-high colorectal cancer. This is a retrospective observational study. This study was conducted at a high-volume tertiary referral cancer center in China. Twenty-four patients of consecutive cases since 2020 to 2022 with mismatch repair-deficient/microsatellite instability-high colorectal cancer who received preoperative single-agent programmed death-1 blockade were retrospectively reviewed. These patients had either bulking tumors scheduled for multivisceral resection, a strong desire for organ preservation, or potentially resectable metastatic lesions. Pathological complete response, clinical complete response, toxicity, R0 resection rate, and complications were evaluated. Patients tolerated preoperative immunotherapy well. The R0 resection rate was 95.2%, and the pathological complete response rate was 47.6%. Three patients (12.5%) were evaluated as having a clinical complete response and then underwent "watch and wait." One-half of the patients with cT4b were spared multivisceral resection, whereas 60% (3/5) achieved pathological complete response. All 3 patients with liver metastases obtained complete response of all liver lesions after programmed death-1 blockade treatment. Grade III postoperative complications occurred in 2 patients. The limitations of this study are as follows: retrospective study, small sample size, and short follow-up. Preoperative anti-programmed death-1 therapy alone as a conversion strategy in initially resected difficult mismatch repair-deficient/microsatellite instability-high colorectal cancer can achieve a high tumor complete response. The use of immunopreoperative therapy in patients with T4b colon cancer or low rectal cancer can reduce multivisceral resection and achieve high organ function preservation. See the Video Abstract . ANTECEDENTES:El uso del bloqueo de muerte programada-1 tiene un efecto terapéutico significativo en pacientes con cáncer colorrectal metastásico deficiente en reparación de desajustes/inestabilidad de microsatélites-alta (dMMR/MSI-H). Sin embargo, los datos sobre el bloqueo preoperatorio de muerte programada-1 con un solo agente son escasos.OBJETIVO:Este estudio tiene como objetivo evaluar la eficacia y seguridad del bloqueo preoperatorio de muerte programada-1 como estrategia de conversión en pacientes con cáncer colorrectal localmente avanzado y metastásico resecable con dMMR/MSI-H.DISEÑO:Este es un estudio observacional retrospectivo.ESCENARIO:Este estudio se realizó en un centro oncológico terciario de referencia de gran volumen en China.PACIENTES:Se revisaron retrospectivamente veinticuatro pacientes de casos consecutivos desde 2020-2022 con cáncer colorrectal y dMMR/MSI-H que recibieron bloqueo preoperatorio de muerte programada-1 con un solo agente. Estos pacientes tenían un tumor voluminoso programado para resección multivisceral, un fuerte deseo de preservación del órgano o lesiones metastásicas potencialmente resecables.PRINCIPALES MEDIDAS DE RESULTADO:Se evaluaron la respuesta patológica completa, la respuesta clínica completa, la toxicidad, la tasa de resección R0 y las complicaciones.RESULTADOS:Los pacientes toleraron bien la inmunoterapia preoperatoria. La tasa de resección R0 fue del 95,2% y la tasa de respuesta patológica completa fue del 47,6%. Tres pacientes (12,5%) fueron evaluados como respuesta clínica completa y luego sometidos a "observar y esperar". La mitad de los pacientes cT4b se salvaron de la resección multivisceral, mientras que el 60% (3/5) lograron una respuesta patológica completa. Los tres pacientes con metástasis hepáticas obtuvieron respuesta completa de todas las lesiones hepáticas después del tratamiento de bloqueo de muerte programada-1. En dos pacientes se produjeron complicaciones postoperatorias de grado III.LIMITACIONES:Las limitaciones de este estudio son las siguientes: estudio retrospectivo, tamaño de muestra pequeño y seguimiento corto.CONCLUSIONES:La terapia preoperatoria anti muerte programada-1 sola como estrategia de conversión en el cáncer colorrectal inicialmente difícil de resecar con dMMR/MSI-H puede lograr una alta respuesta completa tumoral. El uso de terapia inmunopreoperatoria en pacientes con cáncer de colon T4b o cáncer de recto bajo puede reducir la resección multivisceral y lograr una alta preservación de la función del órgano. (Traducción-Dr. Felipe Bellolio ).

Super minimally invasive surgery changing the treatment paradigm for rectal cancer

The treatment mode for patients with low rectal cancer (LRC) is still mainly surgical treatment. With the advancement of medical technology, the current surgical mode is more inclined towards super minimally invasive surgery (SMIS) that preserves organs and functions. SMIS belongs to organ preservation surgery, including non-full thickness and full-thickness resection under digestive endoscopy, laparoscopic or robotic full-thickness resection, and transanal minimally invasive surgery, which can cover all stages of TNM staging. The paper elaborates on the importance of preoperative accurate diagnosis and risk stratification in selecting appropriate SMIS methods, the new progress of imaging technology in accurately predicting lymph node metastasis, providing preoperative TNM staging and risk stratification, and guiding SMIS treatment. Finally, the paper introduces the SMIS surgical options for the treatment of LRC that have been developed and are currently in the clinical research stage, with the aim of maximizing the quality of life for LRC patients.

FP3.9 - Loop ileostomy reversal in anterior resection: A single centre cohort Study

Abstract Aims Defunctioning loop ileostomy is commonly undertaken in &amp;lt;40% of anterior resections especially mid and low rectal cancer resections. Loop ileostomy allows early enteral nutrition and rehabilitation and reduces the impact of post operative ileus, anastomotic leaks and pelvic sepsis complications Closure of loop ileostomy is usually advocated after 3 months of the index malignant colorectal resection. The aim of this study was to assess the reversal intervals and delays in ileostomy reversal. Methods This is a cohort study carried out since January 2008 to December 2023 at a single centre. Descriptive demography &amp; surgical outcomes were evaluated for all Anterior Resections with loop ileostomy. All anterior resections without covering loop ileostomy carried out since 2008 were recruited as controls. Results AR loop ileostomy (n = 152) AR no stoma (n = 297) Mann Whitney U (p test) Age(yrs) 67.0 ± 0.8 68.4 ± 0.7 NS Sex(M:F) 96 : 56 180 : 117 NS ASA(median) 2 2 NS BMI 26.5 ± 0.4 27.2 ± 0.3 NS Lap : Open(n) 94 : 58 220 : 77 &amp;lt; 0.05 Op time(mins) (index op) 256.3 ± 6.8 219.2 ± 4.7 &amp;lt; 0.0001 LOS(days)(index op) 10 ± 4.5 6 ± 3 Reversal (n) 111 Days to reversal 262 ± 102 Reverse op time(mins) 84.3 ± 4.9 LOS reversal(days) 6 ± 3.5 Conclusion Delays in loop ileostomy reversal in our intuition were due to: progressive CRC disease diagnosis, adjuvant treatments, patient frailty/death, patient choice, delays in anastomotic integrity checks, &amp; theatre availability. To avoid delay, reversal should be planned at time of defunctioning loop ileostomy.

SP3.3 - Real World Experience of 600+ Minimally Invasive Abdominoperineal Resections (APR) Done for Low Rectal Cancers in Tertiary Cancer Care Center

Abstract Introduction APR is standard of care surgery for low rectal cancers involving sphincter. Surgery is commonly done in minimally invasive way. Robotic surgery has recently gained popularity due to ease of procedure. Margin positivity and local recurrence still remain a challenge. Methods It is a retrospective study from prospectively maintained database from Aug 2013 to Aug 2023. Surgical and oncological outcome were analyzed using SPSS version 25 software. Results Total 657 minimally invasive APRs were done. All were done in supine lithotomy position. 570 were laparoscopic and 87 robotic. Mean age was 48.4 years. 6 cases were converted to open (5 lap and 1 robotic). Mean BMI was 22.3. Mean distance from anal verge was 3 cm. Majority patients were cT3 (74%). Median blood loss was 150 ml. Clavien Dindo grade III and beyond complications were seen in 11.2%. Mean hospital stay was 7 days. Mean nodes harvested were 13. Mean no of positive nodes were 1.22. Extended resections (extended TME) were 25% in lap and 42% in robotic. Poorly differentiated and signet histology was seen in 27%. CRM positivity was 6.9%. It increases to 15.5% in signet ring histology. Median follow up achieved was 46 months. Local recurrence was 5.5%. Distant recurrence was 20%. 3-year OS and DFS were 73% and 63% respectively. Conclusion In high volume minimally invasive surgery centre, MIS abdominoperineal resection - both laparoscopic and robotic has acceptable surgical and oncological outcomes.

FP2.7 - Results of Lower Rectum Cancer Treatment

Abstract Objective The objective of this study is to evaluate oncological outcomes, specifically, the rate of locoregional recurrences in lower third rectum cancers treated with concurrent radio-chemotherapy and radical surgery. Methods Locoregional and metastatic recurrences were analyzed based on the initial tumor stage, response to neoadjuvant treatment, and the type of surgery. We utilized the biomedical statistics software SPSS24 and Microsoft Excel. Statistical analysis was performed using the chi-square test, with the calculation of the P-value (Pearson's test). Results During the period from 2000 to December 2021, 638 consecutive resections for lower third rectum cancer were conducted. One hundred and sixty-one patients (25.23%) underwent abdominoperineal amputation (AAP), while 477 (74.76%) underwent conservative surgery. There were 389 men and 249 women, with an average age of 51 years (ranging from 20 to 88). Thirty of our patients were classified as T1, 163 as T2, 420 as T3, and 25 as T4. One hundred and thirty-five patients (21%) received preoperative radiotherapy, and four hundred and eighty-six (76%) underwent concurrent preoperative radio-chemotherapy. Two hundred and six patients (43%) had an ultralow colorectal anastomosis, and 252 (52.8%) had a coloanal anastomosis. Local resection was performed in nineteen patients. The mortality rate was 0.78%, and the morbidity rate was 34%, including twenty-seven anastomotic fistulas (5.6%). Forty-one local recurrences were observed (6.4%). Conclusion During surgery for lower rectal cancer, the surgeon's primary concern is to achieve a valid oncological resection, preserve sphincter function, and ensure patients a recurrence-free survival.