Steele, Scott

Background: Transanal total mesorectal excision (taTME) facilitates sphincter preservation in low rectal cancer. Preliminary results and functional outcomes from the North American multicenter phase II taTME trial (NCT03144765) have been published. Three-year outcomes are reported. Methods: Patients with stage I to III rectal adenocarcinoma were enrolled across 11 centers (2017–2022). Endpoints included TME grade, 3-year overall survival, disease-free survival, cancer-specific survival, recurrence, late (beyond 90 d) complications, and stoma-free survival. Surveillance followed National Comprehensive Cancer Network guidelines, with pelvic magnetic resonance imaging (MRI) at 3 years to assess for pelvic sidewall recurrence when possible. Kaplan–Meier analysis assessed oncologic outcomes. Results: One hundred patients underwent taTME for tumors at a median of 5.8 cm from the anal verge, with intersphincteric resection in 36% and handsewn anastomosis in 54%. Median follow-up was 50.9 months. Late complications occurred in 32 patients, including 21 severe (Clavien-Dindo ≥3). Late anastomotic complications occurred in 5 patients; one required surgical revision. Estimated 3-year overall survival, cancer-specific survival, and disease-free survival were 93.7%, 96.6%, and 84.6%, respectively. Distant recurrence occurred in 15 patients (median: 17.6 months), most commonly in the lung and liver. Locoregional recurrence occurred in 2 patients. Preoperative N stage, lymph node yield, tumor deposits, and perineural invasion were associated with recurrence. Among 100 patients diverted at taTME, 97% were stoma-free at 3 years; 4 patients later underwent secondary diversion. Conclusions: Three-year outcomes of this multicenter trial support the safety and efficacy of taTME in resectable mid and low rectal tumors, with outcomes comparable to contemporary studies. Longer-term oncologic and functional outcomes are needed.

3520 Background: Recent analyses highlight nonhierarchical outcomes using the 8 th Edition AJCC staging system for CC. For instance, the 5-year survival rate for stages I and IIIa patients (pts) closely align. Additionally, tumor deposits (TDs) have been established as significant prognostic indicators. The AJCCCCEP commissioned this study to develop an updated pathological staging system for CC focused specifically on pts without distant metastasis (M0), while retaining the existing stage IV classification. Methods: Individual patient data (IPD) from pts diagnosed with cc (2010- 2017) in the NCDB were divided into training (70%) and internal validation (30%) datasets. External validation used IPD from clinical trials. The primary endpoint was overall survival (OS). Risk classification development for M0 pts incorporated ungrouped data on pathologic T categories, the number of involved regional lymph nodes (LN+), and TD counts. Recursive partitioning and regression tree analyses were applied to construct hierarchical staging levels. Pre-specified criteria required survival probabilities to be consecutive and show clear separations using Kaplan-Meier (KM) estimates with pairwise log-rank test P of < 0.005 for the training and < 0.05 for validation analyses. Results: Data from 281,997 pts (median age 67 years, 50% male, 81% white, 55% T3, 19% T4, 44% N+, 26% M+, and 11% with ≥1 TD) were analyzed, with a median follow-up of 7.3 years. The updated staging system (Table) met pre-specified criteria, with all observed pairwise P < 0.0001 in the development and internal validation sets. KM OS curves displayed a hierarchical separation across all sub-levels after the 1 st year of diagnosis. Consistent results were seen in pts treated with adjuvant chemotherapy in 4 trials (all pair-wise P < 0.0001). Conclusions: The proposed pathological staging system for M0 pts fulfills pre-specified criteria for hierarchical risk stratification, validated both internally and externally, and provides an evidence-based update. Pending review process, the AJCCCCEP will recommend that these changes be made to the Version 9 staging protocol for colon cancer to improve prognostication for CC pts. Stage T, # of LN+, # of TD M % of pts 1y OS (CI), % 3y OS (CI), % 5y OS (CI), % I T1, 0, 0 0 5 96 (95-97) 91 (90-92) 84 (83-86) IIa T2, 0, 0 0 10 95 (94-95) 88 (88-89) 80 (79-81) IIb T1, 0, 1+T1, 1+, 0T2, 0, 1+T2, 1-4, 0T3, 0, 0 0 27 93 (92-93) 84 (84-85) 75 (75-76) IIIa T1, 1+, 1+T2, 1-4, 1+T2, 5+, 0T3, 0, 1+T3, 1-4, 0 0 14 92 (91-92) 80 (80-81) 71 (70-72) IIIb T2, 5+, 1+T3, 1-4, 1+T3, 5+, 0T4a, 0-4, 0T4b, 0-2, 0 0 13 86 (86-87) 69 (68-70) 58 (57-59) IIIc T3, 5+, 1+T4a, 0-4, 1+T4a, 5+, anyT4b, 0-2, 1+T4b, 3+, any 0 5 78 (77-80) 53 (51-54) 40 (38-41) IVa Any 1a 19 59 (58-60) 28 (28-29) 17 (16-18) IVb Any 1b 7 43 (42-44) 14 (13-14) 6 (6-7) CI: 95% confidence internal; Peritoneum involvement data were not available before 2018 in NCDB. Thus, IVa/b were based on 7 th Edition.

BACKGROUND: Surgical management of splenic flexure carcinoma remains controversial. OBJECTIVE: This study aimed to establish an expert international consensus on splenic flexure carcinoma management. DESIGN: A 3-round online-based Delphi study was conducted between September 2020 and April 2021. SETTING: The first round included 18 experts from 12 different countries. For the second and third rounds, each expert in the first round was asked to invite 2 more colorectal surgeons (n = 47). Out of 47 invited experts, 89% (n = 42) participated in the second and third rounds of the consensus. INTERVENTIONS: A total of 35 questions were created and sent via the online questionnaire tool. MAIN OUTCOME MEASURES: Levels of recommendation based on voting concordance were graded as follows: more than 75% agreement was defined as strong, between 50% and 75% as moderate, and below 50% as weak. RESULTS: There was moderate consensus on the definition of splenic flexure (55%) as 10 cm from either side where the distal transverse colon turns into the proximal descending colon. Also, experts recommended an abdominopelvic CT scan plus intraoperative exploration (moderate consensus, 72%) for tumor localization and cancer registry. Segmental colectomy was the preferred technique for the management of splenic flexure carcinoma in the elective setting (72%). Moderate consensus was achieved on the technique of complete mesocolic excision and central vascular ligation principles for splenic flexure carcinoma (74%). Only strong consensus was achieved on the surgical approach for minimally invasive surgery (88%). LIMITATIONS: Subjective decisions are based on individual expert clinical experience and not evidence based. CONCLUSIONS: This is the first internationally conducted Delphi consensus study regarding splenic flexure carcinoma. The definition of splenic flexure remains ambiguous. To more effectively compare oncologic outcomes among different cancer registries, guidelines need to be developed to standardize each domain and avoid arbitrary definitions. See Video Abstract at http://links.lww.com/DCR/C143. ESTANDARIZACIÓN DE LA DEFINICIÓN Y MANEJO QUIRÚRGICO DEL CARCINOMA DE ÁNGULO ESPLÉNICO ESTABLECIDO POR UN CONSENSO INTERNACIONAL DE EXPERTOS UTILIZANDO LA TÉCNICA DELPHI: ¿ESPACIO PARA MEJORAR? ANTECEDENTES: El tratamiento quirúrgico del cáncer de ángulo esplénico sigue siendo controvertido. OBJETIVO: Establecer un consenso internacional de expertos sobre el manejo del cáncer del ángulo esplénico. DISEÑO: Se condujo un estudio Delphi en línea de 3 rondas entre septiembre de 2020 y febrero de 2021. ESCENARIO: La primera ronda incluyó a 18 expertos de 12 países distintos. Para la segunda y tercera rondas, a cada experto de la primera ronda se le pidió que invitara a 2 cirujanos colorrectales más de su región (n = 47). De los 47 expertos invitados, el 89% (n = 42) participó en la segunda y tercera ronda del consenso. INTERVENCIONES: Se crearon y enviaron un total de 35 preguntas a través de la herramienta de cuestionario en línea. PRINCIPALES MEDIDAS DE RESULTADO: Los niveles de recomendación basados en la concordancia de votos fueron jerarquizados de la siguiente manera: más del 75% de acuerdo se definió como fuerte, entre 50 y 75% como moderado y por debajo del 50% como débil. RESULTADOS: Hubo un consenso moderado sobre la definición de ángulo esplénico (55%) como 10 cm desde cualquier lado donde el colon transverso distal se convierte en el colon descendente proximal. Así también, los expertos recomendaron la tomografía computarizada abdominopélvica más la exploración intraoperatoria (consenso moderado, 72%) para la localización del tumor y el registro del ángulo esplénico. La colectomía segmentaria fue la técnica preferida para el tratamiento del cáncer de ángulo esplénico en el caso de ser electivo (72%). Se logró un consenso moderado sobre la técnica de escisión completa del mesocolon y los principios de ligadura vascular a nivel central para el cáncer de ángulo esplénico (74%). Solo se logró un fuerte consenso sobre el abordaje quirúrgico para la cirugía mínimamente invasiva (88%). LIMITACIONES: Decisiones subjetivas basadas en la experiencia clínica de expertos individuales y no basadas en evidencia. CONCLUSIONES: Este es el primer estudio internacional de consenso Delphi realizado sobre el cáncer de ángulo esplénico. Si bien encontramos un consenso moderado sobre las modalidades de diagnóstico preoperatorio y el manejo quirúrgico, la definición de ángulo esplénico sigue siendo ambigua. Para comparar de manera más efectiva los resultados oncológicos entre diferentes registros de cáncer, se deben desarrollar pautas para estandarizar cada dominio y evitar definiciones arbitrarias. Consulte Video Resumen en http://links.lww.com/DCR/C143. (Traducción—Dr. Osvaldo Gauto )

256 Background: Current staging for colon cancer utilizing the American Joint Committee on Cancer TNM framework stratifies disease into groups according to how advanced the disease is and provides important standardized, individual prognostic information. Ideally, staging systems should exhibit hierarchical logic, with increasing stage reflecting worse prognosis. We sought to evaluate hierarchy within the 8th edition AJCC staging system for colon cancer. Methods: All patients with primary colon (including rectosigmoid) cancer diagnosed 2010-2017 were identified from the National Cancer Database (NCDB). Patients were only included if they carried a histologic diagnosis of invasive primary (non-recurrent) cancer, underwent radical surgery, and had complete pathologic staging data (T, N, M category data). Patients with missing follow-up data were excluded. Kaplan-Meier curves were used to assess overall survival by AJCC 8th edition pathologic summary stage group to determine whether staging was hierarchical for colon cancer. Multivariable modeling and log likelihood ratio test was then used to identify relative contributions of T and N variables to overall survival. Results: Among 270,584 colon cancer patients, pathologic staging was noted to be hierarchical by T category alone and by N category alone. However, summary staging was non-hierarchical in both instances. Multivariable modeling confirmed the AJCC non-hierarchy issue (colon HRs: 1, 1.54, 2.62, 2.60, 1.02, 2.15, and 4.38 for stage 1 as reference, 2a, 2b, 2c, 3a, 3b, 3c respectively). Multivariable modeling demonstrated that high T category (T4a, T4b) conferred the greatest risk of mortality based on hazard ratio (T4a HR 2.76, T4b HR 3.04), while high T category as well as high N category (N2a, N2b) contributed substantially to the survival model based on z-score. Further modeling assessing the predictive power of T and N category with respect to overall survival demonstrated that T category more strongly predicted overall survival than N category in colon cancer (likelihood chi-square test statistic pT:7009 vs pN:3586). Conclusions: Hierarchy in survival based on AJCC summary stage was not observed for patients with stage II-III colon cancer resulting in a paradoxical better observed survival with some stage III cancer subgroups compared to stage II cancer subgroups. High T category appears to more significantly impact survival than N category for patients with N0-N1 disease, while high N category appears more important for patients with T1-3 disease. Future revisions of the AJCC staging system should account for the differential impact of T and N category identified herein to more accurately confer prognostic information.