INTRODUCTION:Unplanned, delayed readmissions (>30 ds) following oncologic surgeries can increase mortality and care costs and affect hospital quality indices. However, there is a dearth of literature on rectal cancer surgery. Hence, we aimed to assess the risk factors associated with delayed readmissions following rectal cancer surgery to improve targeted interventions, patient outcomes, and quality indices. METHODS:For this case-control study, all adult patients in the US Rectal Cancer Consortium database who underwent surgery and subsequent readmission were included. Multivariable logistic regression described the association of factors associated with delayed readmission. Descriptive statistics were used to ascertain the most common causes of readmission. RESULTS:Of the 1417 patients included in the analysis, 403 (28.4%) patients were readmitted postoperatively. Among these, 101 (25.1%) patients had delayed readmission. The median length of stay for early readmission was significantly longer when compared to delayed readmission (4 versus 2 ds, P < 0.01). American Society of Anesthesiologists-Physical Status score > II [odds ratio = 1.81] was associated with an increased risk of delayed readmissions, while intraoperative pelvic drain placement [odds ratio = 0.57] was associated with a reduced risk. Surgical site infection was the most common cause of delayed (18.4%) and early readmissions (27.4%). CONCLUSIONS:The risk of readmission following surgery for rectal cancer extends beyond the commonly tracked 30 ds, with up to a quarter of readmissions happening more than 30 ds after surgery. Surgical site infection continues to be the leading cause of both early and delayed readmission, underscoring the need to double down on infection prevention bundles.

143 Background: The use of neoadjuvant chemoradiation (NCRT) for upper rectal cancer remains controversial. Our aim was to determine whether NCRT was associated with improved outcomes. Methods: The US Rectal Cancer Consortium was queried for patients who underwent resection of non-metastatic upper rectal cancer (≥12cm from anal verge) from 2007-2017. Primary outcomes were recurrence-free (RFS) and overall survival (OS). Secondary outcomes were postoperative complications. Results: 193 pts met inclusion criteria; 100 (52%) did not receive NCRT and 93 (48%) did. Median age was similar between groups (non-NCRT: 62 yrs; NCRT: 57 yrs; p=0.71). Patients in each group had similar gender and pathological stage (non-NCRT: 22% stage I, 32% stage II, 36% stage III; NCRT: 21% stage I, 23% stage II, 33% stage III; p=0.143). Median follow-up was 31 months (non-NCRT) and 34 months (NCRT). On Kaplan-Meier analysis, NCRT was not associated with improved RFS compared to non-NCRT (3-year RFS 85% vs. 80%; p=0.34) or OS (3-year OS 88% vs. 90%; p=0.49). This finding persisted on multivariable cox regression. R0 resection rate was similar between groups at 99% (non-NCRT) and 97% (NCRT; p=0.27). Anastomotic leak occurred in 11% of both cohorts. Creation of a diverting loop ileostomy (DLI) was nearly 3 times higher in NCRT (82%) versus non-NCRT patients (29%; p<0.001). Conclusions: Among patients with non-metastatic upper rectal cancer, NCRT did not improve survival or recurrence rates, but was associated with a nearly threefold higher DLI rate. Although NCRT is a mainstay of treatment for lower rectal cancer, our results do not support its use in upper rectal cancer. [Table: see text]

Introduction Gender of trainees and attending surgeons has been shown to influence levels of trainee autonomy (TA) during surgical training. In this study, we evaluated the feasibility of an objective performance indicator, the ratio of economy of motion (rEOM), to assess differences in TA by gender during dual-console colorectal procedures. Methods In this retrospective feasibility study, endoscopic videos from 87 procedures were annotated to identify distinct surgical step visits. Utilizing rEOM, each step visit was attributed to either the attending surgeon or the trainee. TA was compared across six female and four male general surgery chief residents, along with one female and three male colorectal surgery fellows. Results During 87 procedures, of which 73 were robotic proctectomies and 14 were robotic right colectomies, a total of 2662 step visits were analyzed. Male fellows performed more step visits during all cases (36.8% versus 21.7%; P = 0.019) and right colectomies (34.0% versus 14.6%; P = 0.021). In cases with male attendings, male fellows completed more step visits per procedure (36.8% versus 21.7%; P = 0.034). During right colectomies with male attendings, all male trainees performed a greater percentage of step visits per procedure (35.7% versus 15.0%; P = 0.020). No significant differences were seen in TA between all male and female trainees in surgeries with female attendings. Conclusions This study demonstrates the feasibility of using rEOM to assess gender differences in TA and/or trainer entrustment. We used rEOM to delineate surgical step ownership, and although our sample size only allows hypotheses-generating inferences, we identified differences in TA between male and female trainees during robotic procedures.

INTRODUCTION:Objective performance indicators (OPIs), machine learning-enabled metrics calculated from robotic systems data, have potential to offer objective insights into surgical skill. There are limited studies investigating OPIs in colorectal surgery. In this study, we aim to identify OPIs that differ expert and novice surgeons during robotic proctectomy (RP). METHODS:Endoscopic videos synchronized to robotic system data were annotated to delineate individual surgical tasks during 30 RPs. We analyzed 541 critical steps: inferior mesenteric artery dissection (78), sigmoid mobilization (167), posterior rectal mobilization (88), and mesorectal dissection (208). OPIs from each step were compared across two expert (>500 robotic procedures) and eleven novice surgeons (<50 procedures). RESULTS:OPIs analyses revealed significant differences between expert and novice surgeons. Across all steps, experts exhibited greater velocity and acceleration for camera, dominant and nondominant arms. During mesenteric artery dissection, experts utilized fewer arm swaps and longer energy activation time. During sigmoid mobilization, experts used fewer arm swaps, shorter camera moving time, fewer camera movements, and less dominant wrist pitch. During rectal mobilization and mesorectal dissection, experts exhibited greater dominant wrist articulation (roll, pitch, and yaw), and longer path length for camera, dominant and nondominant arms. These results identify specific OPIs that designate surgeon expertise during RP. CONCLUSIONS:Step-specific OPIs significantly differ between expert and novice surgeons during RP. With further validation, these metrics may serve as objective tools for benchmarking performance, guiding surgical training curricula, and informing credentialing processes.

INTRODUCTION:Surgical training requires intermittent assessments of trainee entrustment (TE). There is currently no universally accepted objective method to quantify TE during surgery. We investigate using objective performance indicators, automated metrics calculated from robotic systems data, to offer unbiased insights regarding TE. In this feasibility study, we identified differences in TE during dual-console robotic procedures (DCPs). METHODS:Endoscopic videos synchronized to robotic systems data were captured during 87 colorectal DCPs. The ratio of economy of motion (rEOM), defined as the path length of the trainee's robotic arms divided by that of the attending surgeon's, was used to assign each step visit to either the attending or the trainee. TE was compared for 11 general surgery chief residents and four colorectal surgery fellows. Summary statistics were used to describe the pattern along with T-test or Wilcoxon Sum-Rank test for comparisons. RESULTS:The objective performance indicator data were collected during 73 robotic proctectomies (RPs) and 14 robotic right colectomies (RRCs). A total of 2662 surgical step visits were analyzed. Trainees performed a total of 810/2662 (30.4%) step visits, 722/2413 (29.9%) during RPs and 88/249 (35.4%) during RRCs. Fellows performed more step visits than residents during RP (median proportion of steps per procedure 36.4% [IQR: 23.3-48.3%] versus 25.7% [18.6-34.6%], respectively; P = 0.035). Compared to the first half, fellows exhibited greater entrustment during the latter half of the academic year during all DCPs (2nd half: 38.9% [36.4-51.5%] versus 1st half: 25.0% [14.3-39.1%]; P < 0.001) and RPs (2nd half: 39.4% [36.4-51.5%] versus 1st half: 29.1% [14.3-39.8%]; P = 0.008). Residents experienced greater entrustment during RRCs compared to RPs (36.7% [30.8-57.9%] versus 25.7% [18.6-34.6%]; P = 0.022). No differences in TE were seen when comparing procedures for benign versus malignant disease or with different attendings. CONCLUSIONS:We objectively quantified TE during DCPs using rEOM. This supports the feasibility of utilizing rEOM to track.

Background: Surgical resection is the cornerstone of rectal cancer treatment but can be associated with adverse short-term postoperative outcomes. We sought to assess the factors associated with achievement of optimal outcomes among patients undergoing surgery for rectal cancer. Methods: In this multicenter retrospective cohort study, the US Rectal Cancer Consortium database was used to identify patients who underwent surgery for nonmetastatic rectal cancer between 2007 and 2018. The primary outcome was achievement of a Textbook Outcome. A Textbook Outcome is a composite outcome defined as the absence of any postoperative complications, extended length of stay (>75th percentile), 90-day readmission, and 90-day mortality. Multivariable logistic regression analyses were conducted to identify factors associated with the achievement of a Textbook Outcome, and reported as odds ratios and 95% confidence intervals. Results: Among 1,102 patients who underwent surgery for rectal cancer, Textbook Outcome was achieved by 41.8% (n = 461) of patients. On multivariable analyses, American Society of Anesthesiologists-Physical Status >2 (odds ratio 0.66, 95% confidence interval 0.50-0.88), diabetes (0.57, 0.38-0.87), operative time >3.5 hours (0.52, 0.39-0.69), and perioperative packed red blood cells transfusion (0.20, 0.12-0.34) were associated with decreased odds of achieving a Textbook Outcome. Conversely, Enhanced Recovery After Surgery was associated with increased odds of achieving a Textbook Outcome (1.93, 1.45-2.58). Conclusions and Relevance: Despite improvement in recent years, short-term outcomes after rectal cancer surgery remain suboptimal. Patient optimization strategies such as Enhanced Recovery After Surgery are essential to facilitate the achievement of optimal outcomes in patients undergoing rectal cancer surgery. (c) 2024 Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Background Current surgical assessment tools are subjective and nonscalable. Objective performance indicators, calculated from robotic systems data, provide automated data regarding surgeon movements and robotic arm kinematics. We identified objective performance indicators that significantly differed among expert and trainee surgeons during specific steps of robotic right colectomy. Methods Endoscopic videos were annotated to delineate surgical steps during robotic right colectomies. Objective performance indicators were compared during mesenteric dissection, ascending colon mobilization, hepatic flexure mobilization, and bowel preparation for transection. Results Twenty-five robotic right colectomy procedures (461 total surgical steps) performed by 2 experts and 8 trainees were analyzed. Experts exhibited faster camera acceleration and jerk during all steps, as well as faster dominant and nondominant arm acceleration and dominant arm jerk during all steps except distal bowel preparation. During mesenteric dissection, experts used faster camera and dominant arm velocity. During medial-to-lateral ascending colon mobilization, experts used less-dominant wrist yaw and pitch, faster nondominant arm velocity, shorter dominant arm path length, and shorter moving times for camera, dominant arm, and nondominant arm. During lateral-to-medial ascending colon mobilization, experts had faster dominant and nondominant arm velocity and third-arm acceleration. During hepatic flexure mobilization, experts exhibited more camera movements, greater velocity for camera, dominant and nondominant arms, and faster third-arm acceleration. During distal bowel preparation, experts used greater dominant wrist articulation, faster camera velocity, and longer nondominant arm path length. During proximal bowel preparation, experts demonstrated faster nondominant arm velocity. Conclusion Objective performance indicators can differentiate experts from trainees during distinct steps of robotic right colectomy. These automated, objective and scalable metrics can provide personalized feedback for trainees.

Background and Objectives: The RAPIDO trial showed promising rates of pathologic complete response (pCR) after neoadjuvant short-course radiation with consolidation chemotherapy (total neoadjuvant therapy [SC TNT]) for rectal cancer. Only single-center reviews comparing tumor downstaging between SC TNT and long-course chemoradiation (LCRT) have been published in the United States. We reviewed our multi-institutional experience with both. Methods: The US Rectal Cancer Consortium database (2007-2018) including data from six high-volume rectal cancer care centers was reviewed. Patients with nonmetastatic, rectal adenocarcinoma who had neoadjuvant LCRT alone or SC TNT before excision or definitive nonoperative management were included. The primary outcome was the rate of complete response (CR), including pCR or durable (12 month) clinical complete response. Results: Of 857 included patients, 175 (20%) received SC TNT and 682 (80%) received LCRT. The LCRT group had more low tumors (51.8% vs. 37.1%, p < 0.0001) and more clinically node-negative disease (31.8% vs. 22.3%, p < 0.0001). The CR rate was higher after SC TNT (34.1% vs. 20.3%, p = 0.0001). SC TNT was a predictor of CR (OR: 2.52, CI: 1.68-3.78). SC TNT patients completing 5-6 months of consolidation chemotherapy had a CR rate of 42.9%. There was no difference in 3-year PFS. Conclusions: SC TNT increases CR rate when compared to LCRT. For patients seeking nonoperative options or fewer radiation treatments, SC TRT should be preferred over LCRT alone.

Background and ObjectivesAnastomotic leak following colorectal anastomosis adversely impacts short-term, oncologic, and quality-of-life outcomes. This study aimed to assess the impact of omental pedicled flap (OPF) on anastomotic leak among patients undergoing low anastomotic resection (LAR) for rectal cancer using a multi-institutional database.MethodsAdult rectal cancer patients in the US Rectal Cancer Consortium, who underwent a LAR for stage I-III rectal cancer with or without an OPF were included. Patients with missing data for surgery type and OPF use were excluded from the analysis. The primary outcome was the development of anastomotic leaks. Multivariable logistic regression was used to determine the association.ResultsA total of 853 patients met the inclusion criteria and OPF was used in 106 (12.4%) patients. There was no difference in age, sex, or tumor stage of patients who underwent OPF versus those who did not. OPF use was not associated with an anastomotic leak (p = 0.82), or operative blood loss (p = 0.54) but was associated with an increase in the operative duration [beta = 21.42 (95% confidence interval = 1.16, 41.67) p = 0.04].ConclusionsAmong patients undergoing LAR for rectal cancer, OPF use was associated with an increase in operative duration without any impact on the rate of anastomotic leak.

Purpose Anastomotic leak (AL) is a complication of low anterior resection (LAR) that results in substantial morbidity. There is immense interest in evaluating immediate postoperative and long-term oncologic outcomes in patients who undergo diverting loop ileostomies (DLI). The purpose of this study is to understand the relationship between fecal diversion, AL, and oncologic outcomes. Methods This is a retrospective multicenter cohort study using patient data obtained from the US Rectal Cancer Consortium database compiled from six academic institutions. The study population included patients with rectal adenocarcinoma undergoing LAR. The primary outcome was the incidence of AL among patients who did or did not receive DLI during LAR. Secondary outcomes included risk factors for AL, receipt of adjuvant therapy, 3-year overall survival, and 3-year recurrence. Results Of 815 patients, 38 (4.7%) suffered AL after LAR. Patients with AL were more likely to be male, have unintentional preoperative weight loss, and are less likely to undergo DLI. On multivariable analysis, DLI remained protective against AL ( p < 0.001). Diverted patients were less likely to undergo future surgical procedures including additional ostomy creation, completion proctectomy, or pelvic washout for AL. Subgroup analysis of 456 patients with locally advanced disease showed that DLI was correlated with increased receipt of adjuvant therapy for patients with and without AL on univariate analysis (SHR:1.59; [95% CI 1.19–2.14]; p = 0.002), but significance was not met in multivariate models. Conclusion Lack of DLI and preoperative weight loss was associated with anastomotic leak. Fecal diversion may improve the timely initiation of adjuvant oncologic therapy. The long-term outcomes following routine diverting stomas warrant further study.

BACKGROUND:The management of very-low rectal cancer is one of the most challenging issues faced by general and colorectal surgeons. Many feel compelled to pursue abdominoperineal resection (APR) over low anterior resection (LAR) to optimize oncologic outcomes. This study aimed to determine differences in long-term oncologic outcomes between patients undergoing APR or LAR for very-low rectal cancer. METHODS:The United States Rectal Cancer Consortium (2010-2016) was queried for adults who underwent either APR or LAR for stage I-III rectal cancers < 5 cm from anorectal junction and met inclusion criteria. The primary outcome was disease-free survival. Secondary outcomes included overall survival, length of stay, complications, recurrence location, and perioperative factors. RESULTS:A total of 431 patients with very-low rectal cancer who underwent APR or LAR were identified; 154 (35.7%) underwent APR. The overall recurrence rate was 19.6%. The median follow-up was 42.5 months. An analysis adjusted for demographics and pathologic stage observed no difference in disease-free survival between operative types (APR-hazard ratio [HR] = 0.90, 95% CI: 0.53-1.52, P = .70). Secondary outcomes demonstrated no significant difference between operation types, including overall survival (HR = 1.29, 95% CI: 0.71-2.32, P = .39), complications (OR = 1.53, 95% CI: 0.94-2.50, P = .12), or length of stay (estimate: 0.04, SE = 0.25, P = .54). CONCLUSION:We observed no significant difference in disease-free survival or overall survival between patients undergoing APR or LAR for very-low rectal cancer. This analysis supports the treatment of very-low rectal cancer, without sphincter involvement, by either APR or LAR.

IntroductionDespite being a key metric with a significant correlation with the outcomes of patients with rectal cancer, the optimal surgical approach for total mesorectal excision (TME) has not yet been identified. The aim of this study was to assess the association of the surgical approach on the quality of TME and surgical margins and to characterize the surgical and long-term oncologic outcomes in patients undergoing robotic, laparoscopic, and open TME for rectal cancer.MethodsPatients with primary, nonmetastatic rectal adenocarcinoma who underwent either lower anterior resection or abdominoperineal resection via robotic (Rob), laparoscopic (Lap), or open approaches were selected from the US Rectal Cancer Consortium database (2007-2017). Quasi-Poisson regression analysis with backward selection was used to investigate the relationship between the surgical approach and outcomes of interest.ResultsAmong the 664 patients included in the study, the distribution of surgical approaches was as follows: 351 (52.9%) underwent TME via the open approach, 159 (23.9%) via the robotic approach, and 154 (23.2%) via the laparoscopic approach. There were no significant differences in baseline demographics among the three cohorts. The laparoscopic cohort had fewer patients with low rectal cancer (<6 cm from the anal verge) than the robotic and open cohorts (Lap 28.6% versus Rob 59.1% versus Open 45.6%, P = 0.015). Patients who underwent Rob and Lap TME had lower intraoperative blood loss compared with the Open approach (Rob 200 mL [Q1, Q3: 100.0, 300.0] versus Lap 150 mL [Q1, Q3: 75.0, 250.0] versus Open 300 mL [Q1, Q3: 150.0, 600.0], P < 0.001). There was no difference in the operative time (Rob 243 min [Q1, Q3: 203.8, 300.2] versus Lap 241 min [Q1, Q3: 186, 336] versus Open 226 min [Q1, Q3: 178, 315.8], P = 0.309) between the three approaches. Postoperative length of stay was shorter with robotic and laparoscopic approach compared to open approach (Rob 5.0 d [Q1, Q3: 4, 8.2] versus Lap 5 d [Q1, Q3: 4, 8] versus Open 7.0 d [Q1, Q3: 5, 9], P < 0.001). There was no statistically significant difference in the quality of TME between the robotic, laparoscopic, and open approaches (79.2%, 64.9%, and 64.7%, respectively; P = 0.46). The margin positivity rate, a composite of circumferential margin and distal margin, was higher with the robotic and open approaches than with the laparoscopic approach (Rob 8.2% versus Open 6.6% versus Lap 1.9%, P = 0.17), Rob versus Lap (odds ratio 0.21; 95% confidence interval 0.05, 0.83) and Rob versus Open (odds ratio 0.5; 95% confidence interval 0.22, 1.12). There was no difference in long-term survival, including overall survival and recurrence-free survival, between patients who underwent robotic, laparoscopic, or open TME (Figure 1).ConclusionsIn patients undergoing surgery with curative intent for rectal cancer, we did not observe a difference in the quality of TME between the robotic, laparoscopic, or open approaches. Robotic and open TME compared to laparoscopic TME were associated with higher margin positivity rates in our study. This was likely due to the higher percentage of low rectal cancers in the robotic and open cohorts. We also reported no significant differences in overall survival and recurrence-free survival between the aforementioned surgical techniques.

Background: Robotic surgery is perceived to be more complex in obese patients. Objective performance indicators, machine learning-enabled metrics, can provide objective data regarding surgeon movements and robotic arm kinematics. In this feasibility study, we identified differences in objective performance indicators during robotic proctectomy in obese and nonobese patients. Methods: Endoscopic videos were annotated to delineate individual surgical steps across 39 robotic proctectomies (1880 total steps). Thirteen patients were obese and 26 were nonobese. Objective performance indicators during the following steps were analyzed: splenic flexure mobilization, left colon mobilization, pelvic dissection, and rectal transection. Results: The following differences were noted during robotic proctectomy in obese patients: during splenic flexure mobilization, more arm swaps, longer camera path length and velocity; during left colon mobilization, longer step time, more arm swaps, higher camera-related metrics (movement, path length, velocity, acceleration, and jerk), greater dominant arm path length, moving time, and wrist articulation; during anterior pelvic dissection, longer energy activation time, camera path length, and moving time; during posterior pelvic dissection, lower nondominant arm velocity, jerk, and acceleration; during left pelvic dissection, longer energy activation time; during right pelvic dissection, greater camera-related metrics (movement, path length, moving time, and velocity); and during rectal transection, longer step time, more arm swaps, master clutch use and camera movements, greater dominant wrist articulation, and longer dominant arm path length. Conclusion: We report step-specific objective performance indicators that differ during robotic proctectomy for obese and nonobese patients. This is the first study to use objective performance indicators to correlate a patient attribute with surgeon movements and robotic arm kinematics during robotic colorectal surgery. (c) 2024 Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Introduction Patients with resected locally advanced rectal cancer (LARC) and an incomplete total mesorectal excision (TME) have worse oncologic outcomes. The associations between TME grade, adjuvant therapy receipt, and oncologic outcomes have not been well-studied. We aimed to determine the association between adjuvant chemotherapy and oncologic outcomes in patients who underwent neoadjuvant chemoradiation (CRT) or short-course radiotherapy (SCRT) followed by proctectomy and to evaluate this association stratified by TME grade. Materials and methods We analyzed a retrospective multi-institutional cohort of primary LARC patients diagnosed between 2010 and 2018 who received neoadjuvant CRT/SCRT followed by proctectomy. Complete TME was defined as complete mesorectal excision, and noncomplete TME was defined as near-complete or incomplete TME. We used adjusted Cox proportional hazards regression to test the association between adjuvant chemotherapy and mortality or locoregional recurrence (LRR) across groups. Results We identified 746 eligible patients. On final pathology, 101 (13.5%) had noncomplete and 645 (86.5%) had complete TME. Rates of adjuvant chemotherapy receipt were similar between noncomplete and complete TME groups (70.3% and 69.5%, respectively). Mean follow-up interval was 35 mo. Adjuvant chemotherapy was associated with lower risk of mortality (HR 0.27, 95% CI 0.19-0.39, P < 0.001); the same association existed when stratifying patients by TME grade. For patients with a complete TME, adjuvant chemotherapy was associated with lower LRR (HR 0.08, 95% CI 0.01-0.56, P = 0.01). The LRR model for the noncomplete TME group did not converge due to few captured recurrences. Conclusions These data show an association between adjuvant chemotherapy and positive outcomes in LARC patients receiving neoadjuvant CRT/SCRT followed by proctectomy.

INTRODUCTION:Surgeon assessment tools are subjective and nonscalable. Objective performance indicators (OPIs), machine learning-enabled metrics recorded during robotic surgery, offer objective insights into surgeon movements and robotic arm kinematics. In this study, we identified OPIs that significantly differed across expert (EX), intermediate (IM), and novice (NV) surgeons during robotic right colectomy. METHODS:Endoscopic videos were annotated to delineate 461 surgical steps across 25 robotic right colectomies. OPIs were compared among two EX, two IM, and eight NV surgeons during mesenteric dissection, vascular pedicle ligation, right colon and hepatic flexure mobilization, and preparation of the proximal and distal bowel for transection. RESULTS:Compared to NV's, EX's exhibited greater velocity, acceleration and jerk for camera, dominant, nondominant, and third arms across all steps. Compared to NV's, IM's exhibited more arm swaps and master clutch use, higher camera-related metrics (movement, path length, moving time, velocity, acceleration, and jerk), greater dominant wrist pitch and nondominant wrist articulations (roll, pitch, and yaw), longer dominant and nondominant arm path length, and higher velocity, acceleration and jerk for dominant, nondominant, and third arms across all steps. Compared to NV's, EX/IM surgeons utilized more arm swaps, higher camera-related metrics (movement, path length, velocity, acceleration, and jerk), longer nondominant arm path length, and greater velocity, acceleration and jerk for dominant, nondominant, and third arms across all steps. CONCLUSIONS:We report OPIs that discriminate EX, IM, and NV surgeons during RRC. This study is the first to demonstrate feasibility of using OPIs as an objective, scalable way to classify surgeon skill during RRC steps.

BACKGROUND AND OBJECTIVES:The importance of the radial margin for rectal cancer resection is well understood. However, surgeons have deemphasized the distal margin, accepting very close distal margins to perform sphincter-preserving surgery. We hypothesized that distal margins < 1 cm would be an independent risk factor for locoregional recurrence. The objective was to determine whether close distal margins are associated with increased locoregional recurrence risk. METHODS:This was a multi-institutional retrospective cohort study conducted at six academic medical centers including patients who received low anterior resection surgery for primary rectal cancer between 2007 and 2018. RESULTS:Of 556 low anterior resection patients, the rate of close distal margin was 12.8% (n = 71), and the locoregional recurrence rate was 5.0% (n = 28). The locoregional recurrence rate for close distal margin cases was 9.9% (n = 7) compared to 4.3% (n = 21) for distal margins ≥1.0 cm. In multivariable analysis, the only factor significantly associated with locoregional recurrence was close distal margin (adjusted odds ratio: 2.80, confidence interval: 1.08-7.25, p = 0.035). CONCLUSIONS:Rectal cancer patients with close distal margins (<1 cm) following low anterior resection had a significantly higher risk for locoregional recurrence. Therefore, the decision to perform low anterior resection with margins < 1 cm should be taken with caution.

145 Background: For early-stage rectal cancer, minimally invasive surgical (MIS) approaches such as transanal endoscopic microsurgery (TEM) and transanal minimally invasive surgery (TAMIS) have not been widely adopted over conventional transanal excision (TAE). Direct comparisons are lacking. Our aim was to compare oncologic and perioperative outcomes between the two approaches. Methods: We identified patients with Tis or T1 tumors who underwent TAE or MIS (TEM or TAMIS) between 2007-2017 from the US Rectal Cancer Consortium database. Patients who received neoadjuvant therapy were excluded. Primary outcomes were rate of recurrence and recurrence-free survival (RFS). Results: Of 1881 patients, 89 met inclusion criteria: 44 TAE and 45 MIS (20 TEM, 25 TAMIS). Median age was similar between groups (63.5 years TAE vs 61 years MIS; p=0.582). Patients in each group had similar functional status and tumor size (1.86 cm TAE vs 1.79 cm MIS, p=0.837). The majority of patients had tumors ≤ 6 cm from the anal verge (75.7% TAE vs 65.5% MIS, p=0.544). The TAE group had a 10.3% margin positive rate versus 0% in the MIS group (p=0.049). There was a lower incidence of recurrence in the MIS group (4.5%) compared to TAE (26%, p=0.01); all recurred locally except for one in the TAE group. Median follow-up time was 23.7 months. On Kaplan-Meier analysis, MIS approach was associated with improved 5-year RFS (86.4%, p=0.005) and local RFS (86.4%, p=0.01), versus TAE (46.9% and 50.5%, respectively). On univariate cox regression analysis, lymphovascular invasion was associated with worse RFS (HR 4.23, p=0.033) and local RFS (HR 5.26, p=0.02), while MIS approach was associated with improved RFS (HR 0.15, p=0.015) and local RFS (HR 0.17, p=0.023). On multivariable cox regression, only MIS approach remained associated with improved RFS (HR 0.09, p=0.028) and local RFS (HR 0.11, p=0.045). Perioperative complication and readmission rates were equal between the two groups. Conclusions: In patients with Tis and T1 rectal cancers who undergo local excision, an MIS approach (TEM or TAMIS) is associated with a decreased rate of recurrence and improved RFS and local RFS compared to TAE, with no significant difference in perioperative complication rate. The MIS approach should be more frequently incorporated into standard practice. [Table: see text]