The 1 mm rule for circumferential resection margin (CRM) involvement in rectal cancer is deeply embedded in international practice, defining R1 resection as tumour at or within 1 mm of the resection margin. While this threshold has strong evidence in major resections for primary rectal cancer, its universal application is increasingly questioned. Advances in imaging, surgical technique and pathological understanding suggest that R1 status may require context-specific interpretation across three distinct clinical settings: encapsulated nodal involvement in locally advanced rectal cancer (LARC), locally recurrent rectal cancer (LRRC) and locally excised early rectal cancer (LERC). This opinion article reviews current literature, international datasets and emerging evidence to challenge the uniformity of the 1 mm definition. It draws upon The International Collaboration on Cancer Reporting (ICCR) dataset, Royal College of Pathologists (RCPath) guidance and recent large cohort and registry analyses to explore the biological and clinical relevance of close margins in these scenarios. Evidence indicates that the prognostic value of the 1 mm rule varies by anatomical and pathological context. In LARC, a lymph node metastasis abutting the CRM without extracapsular extension behaves biologically as R0 and should not be upstaged. For LRRC, narrow but clear margins (>0 mm) confer equivalent outcomes to wider margins, supporting the use of a 0 mm R1 definition. In LERC, a ≤1 mm margin may be oncologically acceptable in the absence of high-risk histological features. The current evidence supports a tailored approach to R1 definition, preserving rigour while aligning classification with modern oncological, anatomical and pathological realities.

Survival benefit from evidence-based treatment for rectal cancer among older people - Analysis of SEER-medicare.

Risk factors for lymph node metastasis in p/ypT1-2 rectal cancer.

Can large language models extract operative standards from narrative operative reports in rectal cancer?

Alternatives to the double-stapled (DS) technique for creating anastomoses after minimally invasive total mesorectal excision (TME) have been proposed to reduce complications and costs. Robotic intracorporeal single-stapled anastomosis (RISS) was developed as a technically intuitive approach. Standardizing such an intracorporeal robotic technique-which achieves adequate pelvic exposure, precise rectal transection, and secure anastomosis construction-may optimize outcomes, particularly anastomotic leakage (AL). A cohort study was conducted using our prospective institutional database and included patients < 80years who underwent minimally invasive elective TME for extraperitoneal rectal cancer. Patients were allocated to the DS (abdominal stapled transection with double-stapled anastomosis) or RISS (robotic intracorporeal rectal transection with single-stapled anastomosis) groups. The exclusion criteria were nonrestorative procedures, intersphincteric resection, open surgery, and no indocyanine green perfusion assessments. The primary endpoint was 90-day clinical or radiological AL. Among 380 TMEs, 167 met the inclusion criteria (71 RISS; 96 DS). The 90-day AL rate was significantly lower in the RISS group (5.6% vs. 16.7%; p = 0.032). Reintervention (1.4% vs. 10.4%; p = 0.025), overall morbidity (33.3% vs. 52.5%; p = 0.014), and length of stay (p < 0.0001) were lower following RISS. Multivariable analysis revealed that DS technique (odds ratio [OR] 3.3; p = 0.038) and comorbidities (OR 3.1; p = 0.028) independently predicted AL. Each additional stapler firing increased the risk of AL (OR 1.62; p = 0.016), and ≥3 firings predicted AL (OR 4.92; p = 0.011). Compared with DS, RISS was associated with lower anastomotic leakage, morbidity, and reintervention and shorter hospitalization. This standardized robotic approach is safe, reproducible, and potentially cost effective.

Utilizing baseline multiregional MRI radiomics for prediction of tumor deposition and prognosis following neoadjuvant therapy in resectable rectal cancer.

Pathological complete response (pCR) following neoadjuvant chemoradiotherapy (nCRT) for locally advanced rectal cancer (LARC) does not eliminate tumor recurrence risk, with distant metastasis remaining a critical challenge. This study aimed to identify novel prognostic factors for risk stratification in pCR patients after nCRT. We enrolled 149 LARC patients who achieved pCR between 2016 and 2020. Acellular mucin pools (AMP) were classified by the deepest tissue layer of AMP (A0: absent; A1: within the muscularis propria; A2: exceeding the muscularis propria). The primary endpoint was disease-free survival (DFS); secondary endpoints included overall survival (OS) and recurrence patterns. After a median follow-up of 75.3 months, the 5-year OS and DFS rates were 95.3% and 89.9%, respectively. Among 15 recurrence events, all were distant metastases (80% pulmonary). AMP were present in 17.4% (26/149) of patients. Multivariate analysis identified AMP exceeding the muscularis propria (HR = 3.996, 95% CI: 1.073-14.660, P = 0.039), preoperative neutrophil-to-lymphocyte ratio (NLR) >4.4 (HR = 3.658, 95% CI: 1.304-10.263, P = 0.014) and tumour distance from the anal verge on pretreatment magnetic resonance imaging (MRI) (HR = 0.667, 95% CI: 0.481-0.925, P = 0.015) as independent predictors of distant metastasis-free survival (DMFS). A nomogram integrating these factors showed robust discriminative performance for 1-, 3-, and 5-year DMFS (AUC = 0.689, 0.815, 0.795). Meanwhile, AMP exceeding the muscularis propria (HR = 6.632, P = 0.010) and pretreatment MRI-assessed tumour distance from the anal margin (HR = 0.614, P = 0.018) were independent predictors for pulmonary metastasis. AMP exceeding the muscularis propria and high pretreatment NLR are complementary prognostic markers that refine risk stratification in pCR patients, enabling personalized surveillance and treatment strategies to improve outcomes.

The out-of-pocket cost of colorectal cancer care in Nigeria: A prospective analysis.

Feasibility of deep learning-based high-quality CBCT images for adaptive radiotherapy in rectal cancer

ASO Visual Abstract: A Clinical Primer for Defining Time Zero in Rectal Cancer Studies of Nonoperative Management: Implications for Survival and Local Regrowth.

Outcomes reported in randomized controlled trials of rectal cancer treatment: A scoping review for the CORRECT initiative.

Deep-learning-based 3D multi-view multi-parametric MRI fusion model for preoperative T-staging of rectal cancer

HLA-G alleles in Italian patients with locally advanced rectal cancer (LARC).

Setup and target volume shape variation in rectal cancer radiotherapy: a systematic literature review

The LARS score is a practical tool to screen for bowel dysfunction after rectal cancer surgery. However, clinical experience suggests that it may overlook relevant symptoms and/or overestimate impact in some patients. This study aimed to explore whether the International Consensus Definition of LARS complements the LARS score in identifying patients with bowel dysfunction. We conducted a cross-sectional study including patients treated for rectal cancer across two hospitals between January 2021 and December 2024. Demographic and clinical data were collected retrospectively. Functional outcomes were assessed during outpatient follow-up using both the LARS score and the International Consensus Definition criteria. Sixty-two patients were included. According to the LARS score, 39 (62.9%) had "no LARS", 10 (16.1%) "minor LARS" and 13 (21%) "major LARS". Using the International Consensus Definition, 24 (38.7%) met the criteria for LARS. Nine patients (14.5%) were classified differently by the two tools. Five patients classified as "no LARS" by the LARS score met the International Consensus Definition due to unpredictable bowel function and emptying difficulties with a reported impact on daily life. In contrast, four patients with "minor or major LARS" did not meet the International Consensus Definition criteria because no consequences were reported. In this exploratory cross-sectional cohort, the International Consensus Definition did not identify substantially more patients than the LARS score but provided complementary information by linking symptoms to their perceived consequences. Combining both tools may offer a more comprehensive appraisal of LARS until newer multidimensional instruments become available.

Background: The management of rectal cancer has evolved toward response-adapted strategies, including organ preservation in selected patients achieving a clinical complete response (cCR) after neoadjuvant treatment. However, most available evidence derives from clinical trials, and data from real-world clinical practice remain limited. Methods: We conducted a retrospective observational cohort study including consecutive patients with rectal adenocarcinoma treated at a tertiary referral center between January 2021 and December 2025. Baseline clinical, tumor-related, and treatment characteristics were collected. Tumor response was assessed using clinical, endoscopic, and radiological criteria. The primary endpoint was the rate of clinical complete response and the implementation of watch-and-wait strategies. Secondary endpoints included recurrence patterns and exploratory oncologic outcomes according to baseline tumor characteristics. Results: A total of 229 patients were identified, of whom 148 were evaluable for treatment response. Clinical complete response was documented in 56 patients (37.8%), and a watch-and-wait strategy was implemented in 42 patients (28.4%). Higher cCR rates were observed in patients with stage I–II disease and in tumors measuring &lt; 4 cm on baseline magnetic resonance imaging, with cCR rates exceeding 55% in this subgroup. Tumors ≥ 4 cm showed substantially lower response rates. Clinical complete responses were observed across both short-course radiotherapy plus chemotherapy and long-course chemoradiotherapy regimens in patients with small tumors and early-stage disease. Tumor distance from the anal verge was not consistently associated with response. With a median follow-up of 26 months in the watch-and-wait group, five recurrences were observed, including three local recurrences. Conclusions: In this real-world cohort, baseline tumor size and clinical stage were the main determinants of clinical complete response and eligibility for organ-preservation strategies in rectal cancer. Small tumors (&lt;4 cm) showed high response rates regardless of neoadjuvant regimen. These findings support response-adapted, individualized treatment strategies and highlight the importance of tumor burden in selecting candidates for non-operative management in routine clinical practice.

Objectives: Data regarding the demography and clinical characteristics of colorectal cancer (CRC) especially in a country as diverse as India, remains incomplete. This study aims to further examine the clinical and pathological features of colorectal cancer in a cancer centre in South India. Material and Methods: All patients undergoing treatment for colorectal cancer in a tertiary cancer centre were included in this study. The patient characteristics were analysed with respect to location, differentiation, staging, and tumour morphology. Results: A total of 831 consecutive patients were enrolled in the study. Rectal cancer was more prevalent than colon cancer (64% vs 36%). The most common tumourhistological subtype was moderately differentiated adenocarcinoma (78.6%). Mucinous and signet ring cell subtypes were the next most commonly encountered, at 11.4% and 7.6% respectively. Fifty eight percent of patients presented in stage III, and 25.5% were stage IV. Females were found to have a higher T stage at diagnosis than males ( p = 0.03). Colon cancers were more likely to be of a mucinous subtype than rectal cancers ( p = 0.000). In addition, colon cancers were more likely to have poor differentiation when compared to their rectal counterparts ( p = 0.012). Conclusions: Our study identifies that by the time of diagnosis, most patients are already at advanced stages compared to those from higher-income countries. In addition, the proportion of patients presenting with aggressive histological characteristics is also higher than that in other higher-income nations.

Introduction. Anastomotic leakage (AL) remains one of the most severe postoperative complications in the surgical treatment of rectal cancer. Ischemic microcirculatory disturbances in the anastomotic zone represent a leading factor in the development of this complication and may be exacerbated after neoadjuvant radiotherapy (NRT). Conventional methods for assessing bowel perfusion are largely subjective; therefore, objective intraoperative techniques, particularly indocyanine green (ICG) fluorescence angiography, are gaining increasing importance. In addition, monitoring early inflammatory markers-procalcitonin (PCT) and C-reactive protein (CRP)-in combination with morphological tissue assessment has significant prognostic value for the timely detection of AL. Aim. To evaluate the relationship between intraoperative intestinal wall perfusion, inflammatory biomarker levels, and morphological signs of ischemia in predicting anastomotic leakage after rectal resection. Materials and Methods. A prospective cohort study was conducted involving 107 patients with stage I-III rectal cancer who underwent anterior or low anterior resection with colorectal anastomosis. Patients were divided into two groups according to the method of perfusion assessment: the ICG(-) group, which underwent standard visual evaluation, and the ICG(+) group, in which indocyanine green fluorescence angiography was applied. Clinical, morphological, and laboratory parameters (CRP, PCT), as well as instrumental data from intraoperative angiography, were analyzed. Statistical analysis was performed using the Mann–Whitney U test, correlation analysis, and ROC analysis, with a significance level set at p&lt;0.05. Results. Intraoperative indocyanine green (ICG) fluorescence angiography enabled objective assessment of intestinal wall perfusion and allowed adjustment of resection margins in 20.8% of patients. The use of ICG angiography was associated with a lower incidence of anastomotic leakage (5.6%) compared with the control group (18.1%). In patients with low relative fluorescence intensity (ΔI&lt;25%), morphological signs of ischemic injury of the mucosa were more frequently detected, including edema, crypt destruction, and fibrin thrombi in the submucosal layer, corresponding to grade 2-3 according to the Ischemic Injury Score. Elevated procalcitonin levels above 0.5 ng/mL and C-reactive protein levels above 100 mg/L on the third postoperative day were significantly associated with the development of anastomotic leakage. The combined use of ICG angiography parameters, CRP, PCT, and morphological assessment of ischemia demonstrated high prognostic accuracy for predicting the risk of complications (AUC=0.92). Conclusions. Intraoperative indocyanine green fluorescence angiography is an effective method for assessing intestinal wall perfusion during rectal resection. The integration of ICG angiography data with procalcitonin and C-reactive protein levels, as well as morphological signs of ischemia, allows a comprehensive evaluation of anastomotic viability and improves the accuracy of predicting anastomotic leakage. This approach contributes to early risk identification in patients and may reduce the incidence of postoperative complications.

The compelling study by Liu et al delivers a critical verdict: The primary tumor site is not merely an anatomical detail, but a fundamental prognostic imperative in the surgical management of colorectal liver metastases. Their analysis of 178 patients definitively establishes right-sided colonic origin as an independent harbinger of aggressive disease, characterized by significantly higher recurrence rates and inferior survival outcomes compared to left-sided and rectal cancers. This biological dichotomy is further elucidated by the strong association of right-sided tumors with an adverse prognostic profile, including rampant lymph node metastasis, elevated D-dimer (reflecting a pro-thrombotic, pro-metastatic state), hypoalbuminemia, and resistance to neoadjuvant therapy. These findings necessitate an immediate paradigm shift in clinical practice. We can no longer treat colorectal cancer as a monolith. Preoperative risk stratification, surgical decision-making, and adjuvant therapy plans must be tailored according to the primary tumor location. For patients with right-sided primaries, these data suggest a more aggressive multimodal approach and vigilant, personalized surveillance to improve upon the discouraging outcomes this study clearly exposes.

Robotic surgery has transformed the management of oncologic pathologies by offering minimally invasive approaches with improved precision and outcomes. In Colombia, despite its progressive adoption, the scientific literature remains scarce, limiting comprehensive evaluation of its national impact. To analyze the evolution, current status, and future perspectives of robotic surgery in oncology within Colombia, emphasizing its clinical benefits, technological milestones, limitations, and integration with artificial intelligence. A narrative review was conducted using national and international databases. Articles published between 2014 and 2025 concerning robotic surgery in Colombia-with a focus on oncologic applications-were included. he review identified multiple national milestones that mark Colombia's gradual integration of robotic surgery into oncologic practice. Notably, the first documented use of the da Vinci® system in 2014 for transoral robotic surgery (TORS) highlighted enhanced visualization and functional preservation in head and neck cancer. A 2019 multicenter study on robotic thoracic surgery reported zero conversions to thoracotomy, low complication rates, and a learning curve evidenced by progressive reductions in operative time. In gastrointestinal oncology, a 2023 study demonstrated successful implementation with acceptable conversion rates (7.3%) and a 90-day mortality rate of 2.9%. The most recent data from the National Cancer Institute in 2025 showed that robotic rectal cancer surgeries achieved complete mesorectal excision in over 80% of cases, with minimal conversion (4.6%) and acceptable complication rates. Across all specialties, robotic surgery was associated with favorable outcomes in terms of surgical precision, oncologic safety, and recovery time. However, limitations related to cost, equipment availability, and training infrastructure were recurrent themes. Moreover, gaps persist in specialties such as gynecologic oncology and hepatobiliopancreatic surgery, reflecting the uneven adoption of robotics across disciplines. Despite limited publications, current Colombian evidence supports the feasibility, safety, and oncologic effectiveness of robotic surgery. The future of oncologic care in the country hinges on sustained investment, training, and the incorporation of AI-driven innovations to democratize access and optimize outcomes in complex surgical oncology.