Sarcopenia and Myosteatosis Predict Adverse Outcomes After Emergency Laparotomy: A Multi-center Observational Cohort Study.

OBJECTIVE: To determine the relationship between BC, specifically low skeletal muscle mass (sarcopenia) and poor muscle quality (myosteatosis) and outcomes in emergency laparotomy patients. BACKGROUND: Emergency laparotomy has one of the highest morbidity and mortality rates of all surgical interventions. BC objectively identifies patients at risk of adverse outcomes in elective cancer cohorts, however, evidence is lacking in emergency surgery. METHODS: An observational cohort study of patients undergoing emergency laparotomy at ten English hospitals was performed. BC analyses were performed at the third lumbar vertebrae level using preoperative computed tomography images to quantify skeletal muscle index (SMI) and skeletal muscle radiation attenuation (SM-RA). Sex-specific SMI and SM-RA were determined, with the lower tertile splits defining sarcopenia (low SMI) and myosteatosis (low SM-RA). Accuracy of mortality risk prediction, incorporating SMI and SM-RA variables into risk models was assessed with regression modeling. RESULTS: Six hundred ten patients were included. Sarcopenia and myosteatosis were both associated with increased risk of morbidity (52.1% vs 45.1%, P = 0.028; 57.5% vs 42.6%, P = 0.014), 30-day (9.5% vs 3.6%, P = 0.010; 14.9% vs 3.4%, P < 0.001), and 1-year mortality (27.4% vs 11.5%, P < 0.001; 29.7% vs 12.5%, P < 0.001). Risk-adjusted 30-day mortality was significantly increased by sarcopenia [OR 2.56 (95% CI 1.12-5.84), P = 0.026] and myosteatosis [OR 4.26 (2.01-9.06), P < 0.001], similarly at 1-year [OR 2.66 (95% CI 1.57-4.52), P < 0.001; OR2.08 (95%CI 1.26-3.41), P = 0.004]. BC data increased discrimination of an existing mortality risk-prediction model (AUC 0.838, 95% CI 0.835-0.84). CONCLUSION: Sarcopenia and myosteatosis are associated with increased adverse outcomes in emergency laparotomy patients.

Clinical Evaluation of Intraoperative Near Misses in Laparoscopic Rectal Cancer Surgery.

OBJECTIVE: To investigate the frequency, nature, and severity of intraoperative adverse near miss events within advanced laparoscopic surgery and report any associated clinical impact. BACKGROUND: Despite implementation of surgical safety initiatives, the intraoperative period is poorly documented with evidence of underreporting. Near miss analyses are undertaken in high-risk industries but not in surgical practice. METHODS: Case video and data from 2 laparoscopic total mesorectal excision randomized controlled trials were analyzed (ALaCaRT ACTRN12609000663257, 2D3D ISRCTN59485808). Intraoperative adverse events were identified and categorized using the observational clinical human reliability analysis technique. The EAES classification was applied by 2 blinded assessors. EAES grade 1 events (nonconsequential error, no damage, or need for correction) were considered near misses. Associated clinical impact was assessed with early morbidity and histopathology outcomes. RESULTS: One hundred seventy-five cases contained 1113 error events. Six hundred ninety-eight (62.7%) were near misses (median 3, IQR 2-5, range 0-15) with excellent inter-rater and test-retest reliability (κ=0.86, 95% CI 0.83-0.89, P < 0.001 and κ=0.88, 95% CI 0.85-0.9, P < 0.001 respectively). Significantly more near misses were seen in patients who developed early complications (4 (3-6) vs. 3 (2-4), P < 0.001). Higher numbers of near misses were seen in patients with more numerous (P = 0.002) and more serious early complications (P = 0.003). Cases containing major intraoperative adverse events contained significantly more near misses (5 (3-7) vs. 3 (2-5), P < 0.001) with a major event observed for every 19.4 near misses. CONCLUSION: Intraoperative adverse events and near misses can be reliably and objectively captured in advanced laparoscopic surgery. Near misses are commonplace and closely associated with morbidity outcomes.

Impact of anaemia at discharge following colorectal cancer surgery.

OBJECTIVES: Preoperative anaemia is common in patients with colorectal cancer and increasingly optimised prior to surgery. Comparably little attention is given to the prevalence and consequences of postoperative anaemia. We aimed to investigate the frequency and short- or long-term impact of anaemia at discharge following colorectal cancer resection. METHODS: A dedicated, prospectively populated database of elective laparoscopic colorectal cancer procedures undertaken with curative intent within a fully implemented ERAS protocol was utilised. The primary endpoint was anaemia at time of discharge (haemoglobin (Hb) < 120 g/L for women and < 135 g/L for men). Patient demographics, tumour characteristics, operative details and postoperative outcomes were captured. Median follow-up was 61 months with overall survival calculated with the Kaplan-Meier log rank method and Cox proportional hazard regression based on anaemia at time of hospital discharge. RESULTS: A total of 532 patients with median 61-month follow-up were included. 46.4% were anaemic preoperatively (cohort mean Hb 129.4 g/L ± 18.7). Median surgical blood loss was 100 mL (IQR 0-200 mL). Upon discharge, most patients were anaemic (76.6%, Hb 116.3 g/L ± 14, mean 19 g/L ± 11 below lower limit of normal, p < 0.001). 16.7% experienced postoperative complications which were associated with lower discharge Hb (112 g/L ± 12 vs. 117 g/L ± 14, p = 0.001). Patients discharged anaemic had longer hospital stays (7 [5-11] vs. 6 [5-8], p = 0.037). Anaemia at discharge was independently associated with reduced overall survival (82% vs. 70%, p = 0.018; HR 1.6 (95% CI 1.04-2.5), p = 0.034). CONCLUSION: Anaemia at time of discharge following elective laparoscopic colorectal cancer surgery and ERAS care is common with associated negative impacts upon short-term clinical outcomes and long-term overall survival.

3D laparoscopy does not reduce operative duration or errors in day-case laparoscopic cholecystectomy: a randomised controlled trial.

BACKGROUND: Contemporary 3D platforms have overcome past deficiencies. Available trainee and laboratory studies suggest stereoscopic imaging improves performance but there is little clinical data or studies assessing specialists. We aimed to determine whether stereoscopic (3D) laparoscopic systems reduce operative time and number of intraoperative errors during specialist-performed laparoscopic cholecystectomy (LC). METHODS: A parallel arm (1:1) randomised controlled trial comparing 2D and 3D passive-polarised laparoscopic systems in day-case LC using was performed. Eleven consultant surgeons that had each performed > 200 LC (including > 10 3D LC) participated. Cases were video recorded and a four-point difficulty grade applied. The primary outcome was overall operative time. Subtask time and the number of intraoperative consequential errors as identified by two blinded assessors using a hierarchical task analysis and the observational clinical human reliability analysis technique formed secondary endpoints. RESULTS: 112 patients were randomised. There was no difference in operative time between 2D and 3D LC (23:14 min (± 10:52) vs. 20:17 (± 9:10), absolute difference - 14.6%, p = 0.148) although 3D surgery was significantly quicker in difficulty grade 3 and 4 cases (30:23 min (± 9:24), vs. 18:02 (± 7:56), p < 0.001). No differences in overall error count was seen (total 47, median 1, range 0-4 vs. 45, 1, 0-3, p = 0.62) although there were significantly fewer 3D gallbladder perforations (15 vs. 6, p = 0.034). CONCLUSION: 3D laparoscopy did not reduce overall operative time or error frequency in laparoscopic cholecystectomies performed by specialist surgeons. 3D reduced Calot's dissection time and operative time in complex cases as well as the incidence of iatrogenic gallbladder perforation (NCT01930344).

Factors Predicting Operative Difficulty of Laparoscopic Total Mesorectal Excision.

BACKGROUND: Laparoscopic total mesorectal excision is a challenging procedure requiring high-quality surgery for optimal outcomes. Patient, tumor, and pelvic factors are believed to determine difficulty, but previous studies were limited to postoperative data. OBJECTIVE: This study aimed to report factors predicting laparoscopic total mesorectal excision performance by using objective intraoperative assessment. DESIGN: Data from a multicenter laparoscopic total mesorectal excision randomized trial (ISRCTN59485808) were reviewed. SETTING: This study was conducted at 4 centers in the United Kingdom. PATIENTS AND INTERVENTION: Seventy-one patients underwent elective laparoscopic total mesorectal excision for rectal adenocarcinoma with curative intent: 53% were men, mean age was 69 years, body mass index was 27.7, tumor height was 8.5 cm, 24% underwent neoadjuvant therapy, and 25% had previous surgery. MAIN OUTCOME MEASURES: Surgical performance was assessed through the identification of intraoperative adverse events by using observational clinical human reliability analysis. Univariate analysis and multivariate binomial regression were performed to establish factors predicting the number of intraoperative errors, surgeon-reported case difficulty, and short-term clinical and histopathological outcomes. RESULTS: A total of 1331 intraoperative errors were identified from 365 hours of surgery (median, 18 per case; interquartile range, 16-22; and range, 9-49). No patient, tumor, or bony pelvimetry measurement correlated with total or pelvic error count, surgeon-reported case difficulty, cognitive load, operative data, specimen quality, number or severity of 30-day morbidity events and length of stay (all r not exceeding ±0.26, p > 0.05). Mesorectal area was associated with major intraoperative adverse events (OR, 1.09; 95%CI, 1.01-1.16; p = 0.015) and postoperative morbidity (OR, 1.1; 95% CI, 1.01-1.2; p = 0.033). Obese men were subjectively reported as harder cases (24 vs 36 mm, p = 0.042), but no detrimental effects on performance or outcomes were seen. LIMITATIONS: Our sample size is modest, risking type II errors and overfitting of the statistical models. CONCLUSION: Patient, tumor, and bony pelvic anatomical characteristics are not seen to influence laparoscopic total mesorectal excision operative difficulty. Mesorectal area is identified as a risk factor for intraoperative and postoperative morbidity. See Video Abstract at http://links.lww.com/DCR/B35. FACTORES QUE PREDICEN LA DIFICULTAD OPERATIVA DE LA ESCISIÓN MESORRECTAL TOTAL LAPAROSCÓPICA: La escisión mesorrectal total laparoscópica es un procedimiento desafiante. Para obtener resultados óptimos, se requiere cirugía de alta calidad. Se cree que, factores como el paciente, el tumor y la pelvis, determinan la dificultad, pero estudios previos solamente se han limitado a datos postoperatorios.Informar de los factores que predicen el resultado de la escisión mesorrectal total laparoscópica, mediante una evaluación intraoperatoria objetiva.Datos de un ensayo multicéntrico y randomizado de escisión mesorrectal total laparoscópica (ISRCTN59485808).Cuatro centros del Reino Unido.Un total de 71 pacientes fueron sometidos a escisión mesorrectal total laparoscópica electiva, para adenocarcinoma rectal con intención curativa. 53% hombres, edad media, índice de masa corporal y altura del tumor 69, 27.7 y 8.5 cm respectivamente, 24% terapia neoadyuvante y 25% cirugía previa.Rendimiento quirúrgico evaluado mediante la identificación de eventos intraoperatorios adversos, mediante el análisis clínico observacional de confiabilidad humana. Se realizaron análisis univariado y la regresión binomial multivariada para establecer factores que predicen el número de errores intraoperatorios, reportes del cirujano sobre la dificultad del caso y los resultados clínicos e histopatológicos a corto plazo.Se identificaron un total de 1,331 errores intraoperatorios en 365 horas de cirugía (media de 18 por caso, IQR 16-22, rango 9-49). Ningún paciente, tumor o medición de pelvimetría pélvica, se correlacionó con la cuenta de errores pélvicos o totales, reporte del cirujano sobre dificultad del caso, carga cognitiva, datos operativos, calidad de la muestra, número o gravedad de eventos de morbilidad de 30 días y duración de la estadía (todos r <± 0.26, p > 0.05). El área mesorrectal se asoció con eventos adversos intraoperatorios importantes (OR, 1.09; IC 95%, 1.01-1.16; p = 0.015) y morbilidad postoperatoria (OR, 1.1; IC 95%, 1.01-1.2; p = 0.033). Como información subjetiva, hombres obesos fueron casos más difíciles (24 mm frente a 36 mm, p = 0.042) pero no se observaron efectos perjudiciales sobre el rendimiento o los resultados.Nuestro tamaño de muestra es un modesto riesgo de errores de tipo II y el sobreajuste de los modelos estadísticos.No se observa que las características anatómicas del paciente, tumor y pelvis ósea influyan en la dificultad operatoria de la escisión mesorrectal laparoscópica total. El área mesorrectal se identifica como un factor de riesgo para la morbilidad intraoperatoria y postoperatoria. Vea el resumen del video en http://links.lww.com/DCR/B35.

The use of 3D laparoscopic imaging systems in surgery: EAES consensus development conference 2018.

BACKGROUND: The use of 3D laparoscopic systems is expanding. The European Association of Endoscopic Surgery (EAES) initiated a consensus development conference with the aim of creating evidence-based statements and recommendations for the surgical community. METHODS: Systematic reviews of the PubMed and Embase libraries were performed to identify evidence on potential benefits of 3D on clinical practice and patient outcomes. Statements and recommendations were prepared and unanimously agreed by an international surgical and engineering expert panel which were presented and voted at the EAES annual congress, London, May 2018. RESULTS: 9967 abstracts were screened with 138 articles included. 18 statements and two recommendations were generated and approved. 3D significantly shortened operative time (mean difference 11 min (8% [95% CI 20.29-1.72], I2 96%)). A significant reduction in complications was observed when 3D systems were used (RR 0.75, [95 CI% 0.60-0.94], I2 0%) particularly for cases involving laparoscopic suturing (RR 0.57 [95% CI 0.35-0.90], I2 0%). In 69 box trainer or simulator studies, 64% concluded trainees were significant faster and 62% performed fewer errors when using 3D. CONCLUSION: We recommend the use of 3D vision in laparoscopy to reduce the operative time (grade of recommendation: low). Future robust clinical research is required to specifically investigate the potential benefit of 3D laparoscopy system on complication rates (grade of recommendation: high).

EAES and SAGES 2018 consensus conference on acute diverticulitis management: evidence-based recommendations for clinical practice.

BACKGROUND: Acute diverticulitis (AD) presents a unique diagnostic and therapeutic challenge for general surgeons. This collaborative project between EAES and SAGES aimed to summarize recent evidence and draw statements of recommendation to guide our members on comprehensive AD management. METHODS: Systematic reviews of the literature were conducted across six AD topics by an international steering group including experts from both societies. Topics encompassed the epidemiology, diagnosis, management of non-complicated and complicated AD as well as emergency and elective operative AD management. Consensus statements and recommendations were generated, and the quality of the evidence and recommendation strength rated with the GRADE system. Modified Delphi methodology was used to reach consensus among experts prior to surveying the EAES and SAGES membership on the recommendations and likelihood to impact their practice. Results were presented at both EAES and SAGES annual meetings with live re-voting carried out for recommendations with < 70% agreement. RESULTS: A total of 51 consensus statements and 41 recommendations across all six topics were agreed upon by the experts and submitted for members' online voting. Based on 1004 complete surveys and over 300 live votes at the SAGES and EAES Diverticulitis Consensus Conference (DCC), consensus was achieved for 97.6% (40/41) of recommendations with 92% (38/41) agreement on the likelihood that these recommendations would change practice if not already applied. Areas of persistent disagreement included the selective use of imaging to guide AD diagnosis, recommendations against antibiotics in non-complicated AD, and routine colonic evaluation after resolution of non-complicated diverticulitis. CONCLUSION: This joint EAES and SAGES consensus conference updates clinicians on the current evidence and provides a set of recommendations that can guide clinical AD management practice.

Does the number of operating specialists influence the conversion rate and outcomes after laparoscopic colorectal cancer surgery?

BACKGROUND: Laparoscopic techniques in colorectal surgery have been widely utilised due to short-term patient benefits but conversion to open surgery is associated with adverse short- and long-term patient outcomes. The aim of this study was to investigate the influence of dual specialist operating on the conversion rate and patient outcomes following laparoscopic colorectal surgery. METHODS: A prospectively populated colorectal cancer surgery database was reviewed. Cases were grouped into single or dual consultant procedures. Cluster analysis and odds ratio (OR) were used to identify risk factors for conversion. Primary outcome measures were conversion to open and five year overall survival (OS) calculated using the Kaplan-Meier log-rank method. RESULTS: 750 patients underwent laparoscopic colorectal cancer resection between 2002 and 2015 (median age 73, 319 (42.5%) female, 282 (37.6%) rectal malignancies, 135 patients (18%) had two consultants). The single surgeon conversion rate was 20.4% compared to 5.5% for dual operating (OR 4.4, 95% CI 1.87-10.2, p < 0.001). There were no demographic or tumour differences between the laparoscopic/converted and number of surgeon groups. Two-step cluster analysis identified cluster I (lower risk) 406 patients, 8% converted and cluster II (higher risk) 261 patients, conversion rate 30%. Median follow-up was 48 months (range 0-168). Five-year OS was significantly inferior for both converted and single surgeon cases (63% vs. 77%, p < 0.001 and 61% vs. 70%, p = 0.033, respectively). CONCLUSION: In selected colorectal cancer patients operated by fully trained laparoscopic surgeons, we observed a reduction in conversion with associated long-term survival benefit from dual operating specialists.

Factors predicting outcome from enhanced recovery programmes in laparoscopic colorectal surgery: a systematic review.

OBJECTIVE: To perform a systematic review of published literature for the factors reported to predict outcomes of enhanced recovery after surgery (ERAS) programmes following laparoscopic colorectal surgery. BACKGROUND: ERAS programmes and the use of laparoscopy have been widely adopted in colorectal surgery bringing short-term patient benefit. However, there is a minority of patients that do not benefit from these strategies and their identification is not well characterised. The factors that underpin outcomes from ERAS programmes for laparoscopic patients are not understood. METHODS: A systematic search of the MEDLINE, Embase and Cochrane databases was conducted to identify suitable articles published between 2000 and 2015. The search strategy captured terms for ERAS, colorectal resection, prediction and outcome measures. RESULTS: Thirty-four studies containing 10,861 laparoscopic resections were included. Thirty-one (91 %) studies were confined to elective cases. Predictive analysis of outcome was most frequently based on length of stay (LOS), morbidity and readmission which were the main outcome measures of 29 (85 %), 26 (76 %) and 18 (53 %) of the included studies, respectively. Forty-seven percentage of included studies investigated the impact of ERAS programme compliance on these outcomes. Reduced protocol compliance was the most frequently identified modifiable predictive factor for adverse LOS, morbidity and readmission. CONCLUSION: Protocol compliance is the most frequently reported predictive factor for outcomes of ERAS programmes following laparoscopic colorectal resection. Reduced compliance increases LOS, morbidity and readmission to hospital. The impact of compliance with individual ERAS protocol elements is insufficiently studied, and the lack of a standardised framework for evaluating ERAS programmes makes it difficult to draw definite conclusions about which factors exert the greatest impact on outcome after laparoscopic colorectal resection.

The relevance of the Siewert classification in the era of multimodal therapy for adenocarcinoma of the gastro-oesophageal junction.

INTRODUCTION: The Siewert classification has been used to plan treatment for tumours of the gastro-oesophageal junction since its proposal in the 1980s. The purpose of this study was to assess its continued relevance by evaluating whether there were differences in the biology and clinical characteristics of adenocarcinomas by Siewert type, in a contemporary cohort of patients, in whom the majority had received neoadjuvant chemotherapy. METHODS: A prospective database was reviewed for all patients who underwent resection from 2005 to 2011 and analysed with regard to Siewert classification determined from the pathological specimen, treatment and clinicopathological outcomes. RESULTS: Two hundred and sixteen patients underwent oesophagogastric resection: 133 for type I, 51 for type II and 33 for type III tumours. 135 Patients (62.5%) received neoadjuvant chemotherapy with no difference between groups. There were no significant differences in age, sex, pT stage, pN stage, pM stage, ASA, or inpatient complications between patients with adenocarcinoma based on their Siewert classification. There was a significant increase in maximum tumour diameter (P = 0.023), perineural invasion (P = 0.021) and vascular invasion (P = 0.020), associated with more distal tumours (Type III > Type II > Type I). Median overall survival was significantly shorter for more distal tumours (Type I: 4.96 years vs. Type II: 3.3 years vs. Type III: 2.64 years; P = 0.04). The surgical approach did not influence survival. CONCLUSION: In the era of multi-modal treatment pathological Siewert tumour type is of prognostic value, as patients with Type III disease are likely to have larger and more aggressive tumours that lead to worse outcomes.

Urinary Volatile Organic Compound Testing in Fast-Track Patients with Suspected Colorectal Cancer.

Colorectal symptoms are common but only infrequently represent serious pathology, including colorectal cancer (CRC). A large number of invasive tests are presently performed for reassurance. We investigated the feasibility of urinary volatile organic compound (VOC) testing as a potential triage tool in patients fast-tracked for assessment for possible CRC. A prospective, multi-center, observational feasibility study was performed across three sites. Patients referred to NHS fast-track pathways for potential CRC provided a urine sample that underwent Gas Chromatography-Mass Spectrometry (GC-MS), Field Asymmetric Ion Mobility Spectrometry (FAIMS), and Selected Ion Flow Tube Mass Spectrometry (SIFT-MS) analysis. Patients underwent colonoscopy and/or CT colonography and were grouped as either CRC, adenomatous polyp(s), or controls to explore the diagnostic accuracy of VOC output data supported by an artificial neural network (ANN) model. 558 patients participated with 23 (4%) CRC diagnosed. 59% of colonoscopies and 86% of CT colonographies showed no abnormalities. Urinary VOC testing was feasible, acceptable to patients, and applicable within the clinical fast track pathway. GC-MS showed the highest clinical utility for CRC and polyp detection vs. controls (sensitivity = 0.878, specificity = 0.882, AUROC = 0.896) but it is labour intensive. Urinary VOC testing and analysis are feasible within NHS fast-track CRC pathways. Clinically meaningful differences between patients with cancer, polyps, or no pathology were identified suggesting VOC analysis may have future utility as a triage tool.

Association of Surgical Skill Assessment With Clinical Outcomes in Cancer Surgery.

Importance: Complex surgical interventions are inherently prone to variation yet they are not objectively measured. The reasons for outcome differences following cancer surgery are unclear. Objective: To quantify surgical skill within advanced laparoscopic procedures and its association with histopathological and clinical outcomes. Design, Setting, and Participants: This analysis of data and video from the Australasian Laparoscopic Cancer of Rectum (ALaCaRT) and 2-dimensional/3-dimensional (2D3D) multicenter randomized laparoscopic total mesorectal excision trials, which were conducted at 28 centers in Australia, the United Kingdom, and New Zealand, was performed from 2018 to 2019 and included 176 patients with clinical T1 to T3 rectal adenocarcinoma 15 cm or less from the anal verge. Case videos underwent blinded objective analysis using a bespoke performance assessment tool developed with a 62-international expert Delphi exercise and workshop, interview, and pilot phases. Interventions: Laparoscopic total mesorectal excision undertaken with curative intent by 34 credentialed surgeons. Main Outcomes and Measures: Histopathological (plane of mesorectal dissection, ALaCaRT composite end point success [mesorectal fascial plane, circumferential margin, ≥1 mm; distal margin, ≥1 mm]) and 30-day morbidity. End points were analyzed using surgeon quartiles defined by tool scores. Results: The laparoscopic total mesorectal excision performance tool was produced and shown to be reliable and valid for the specialist level (intraclass correlation coefficient, 0.889; 95% CI, 0.832-0.926; P < .001). A substantial variation in tool scores was recorded (range, 25-48). Scores were associated with the number of intraoperative errors, plane of mesorectal dissection, and short-term patient morbidity, including the number and severity of complications. Upper quartile-scoring surgeons obtained excellent results compared with the lower quartile (mesorectal fascial plane: 93% vs 59%; number needed to treat [NNT], 2.9, P = .002; ALaCaRT end point success, 83% vs 58%; NNT, 4; P = .03; 30-day morbidity, 23% vs 50%; NNT, 3.7; P = .03). Conclusions and Relevance: Intraoperative surgical skill can be objectively and reliably measured in complex cancer interventions. Substantial variation in technical performance among credentialed surgeons is seen and significantly associated with clinical and pathological outcomes.

FDG PET/CT Can Assess the Response of Locally Advanced Rectal Cancer to Neoadjuvant Chemoradiotherapy: Evidence From Meta-analysis and Systematic Review.

INTRODUCTION: Neoadjuvant chemoradiotherapy (CRT) is indicated in locally advanced rectal adenocarcinoma where there is a high risk of local recurrence based on preoperative imaging. Optimal radiological assessment of CRT response is unknown, and metabolic assessment of the tumor has been suggested to gauge response before surgical resection. PATIENTS AND METHODS: A systematic search of the MEDLINE database was performed using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement to identify papers comparing pre- and post-CRT PET/CT in patients with locally advanced rectal adenocarcinoma with histopathological assessment of tumor regression. Papers were assessed with the QUADAS (Quality Assessment of Diagnostic Accuracy Studies) tool. Meta-analysis was performed for response index (RI) and SUVmax post-CRT. RESULTS: Ten of 69 studies met inclusion criteria containing a total of 538 patients. Methodological quality was high with low heterogeneity. In all studies, post-CRT PET/CT showed a reduction in SUVmax and the RI irrespective of histological findings. Tumors confirmed to have regressed after CRT had a mean difference of 12.21% higher RI (95% confidence interval, 6.51-17.91; P < 0.00001) compared with nonresponders. Mean difference between pre- and post-CRT SUVmax groups was -2.48 (95% confidence interval, -3.06 to -1.89; P < 0.00001) with histopathological responders having a lower post-CRT SUVmax. CONCLUSIONS: The available evidence suggests that PET/CT may be a useful addition to the current imaging modalities in the assessment of treatment response.