Assessment of postoperative circulating tumour DNA to predict early recurrence in patients with stage I-III right-sided colon cancer: prospective observational study.

BACKGROUND: Right-sided colon cancer (RCC) differs in mutation profile and risk of recurrence compared to distal colon cancer. Circulating tumour DNA (ctDNA) present after surgery can identify patients with residual disease after curative surgery and predict risk of early recurrence. METHODS: This is a prospective observational biomarker trial with exploration of ctDNA in 50 non-metastatic RCC patients for which oncological right-sided colectomy was performed. Blood samples were collected preoperatively, within 1 month post surgery, 3 months (not mandatory), 6 months and every 6 months thereafter. Plasma cell free DNA and/or tumour was investigated for cancer-related mutations by the next-generation sequencing (NGS) panel AVENIO surveillance specifically designed for ctDNA analysis. Detected mutations were quantified using digital droplet PCR (ddPCR) for follow-up. Recurrence-free survival was explored. RESULTS: 50 patients were recruited. Somatic cancer-related mutations were detected in 47/50 patients. ddPCR validated results from NGS for 27/34 (plasma) and 72/72 samples (tumour). Preoperative ctDNA was detected in 31/47 of the stage I/III patients and the majority of ctDNA positive patients showed reduction of ctDNA after surgery (27/31). ctDNA-positive patients at first postoperative sample had high recurrence risk compared to patients without measurable ctDNA (adjusted hazard ratio: 172.91; 95% c.i.: 8.70 to 3437.24; P: 0.001). CONCLUSION: ctDNA was detectable in most patients with non-metastatic RCC before surgery. Positive postoperative ctDNA was strongly associated with early recurrence. Detectable postoperative ctDNA is a prognostic factor with high (100%) positive predictive value for recurrence in this cohort of non-metastatic RCC. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov ID: NCT03776591.

Translation and validation of the Norwegian version of the postoperative quality of recovery score QoR-15.

BACKGROUND: As patient-centered care gains more attention, assessing the patient's perspective on their recovery has become increasingly important. In response to the need for a reliable and valid patient reported outcome measurement tool for major surgical resections in Norway. The Norwegian Registry for Gastrointestinal Surgery (NORGAST) initiated a project to translate and evaluate QoR-15's psychometric properties for patients going through general, gastrointestinal (GI), and hepato-pancreato-biliary (HPB) resectional surgery. METHODS: After a translation and adaption of the original version of QoR-15 into Norwegian, the QoR-15NO was psychometrically evaluated including a confirmatory factor analysis to test for unidimensionality, as well as tests for content validity, internal consistency, measurement error, construct validity, feasibility, and responsiveness. This process included cognitive interviews using a structured interview guide. Further, patients who underwent various types of GI/HPB surgery at five hospitals in different parts of Norway completed the QoR-15NO before surgery and on the first or second day after surgery. The impact of surgery was classified according to Surgical Outcome Risk Tool v2 (SORT), in extra major/complex, major, intermediate, and minor. RESULTS: This study included 324 patients with 83% return rate with both pre- and postoperative forms. There were negative correlations between duration of surgery and postoperative QoR-15 score and the difference between post- and preoperative score (change score). Individuals who had gone through surgery with major impact had a lower postoperative mean QoR-15 score (97) than their counterparts who had experienced either medium (QoR-15: 110) or minor (QoR15: 119) impact surgery. Cronbach's alpha (0.88) and Omega Alpha Total (ωt = 0.90) indicate that the scale has good to very good internal consistency. Test-retest reliability was measured by Intra-class Correlation Coefficient to ICC = 0.70. Confirmatory factor analyses supported that a one-factor model with correlated residuals had a good fit to data. CONCLUSION: This study supports QoR-15NO as a valid, essentially unidimensional, feasible, and responsive instrument among patients undergoing general, GI, and HPB resectional surgery in Norway. The total QoR-15NO score provides important information that can be used in an everyday clinical setting and integrated into NORGAST.

Complications after open and laparoscopic right-sided colectomy with central lymphadenectomy for colon cancer: randomized controlled trial.

BACKGROUND: A central lymphadenectomy in right-sided colon cancer involves dissection along the superior mesenteric axis, but the extent is debated due to a lack of consensus and the fear of major complications. This randomized controlled trial compared the rate of postoperative morbidity in patients undergoing laparoscopic versus open right-sided colectomy with central lymphadenectomy. METHODS: This open, prospective, randomized controlled trial compared patients operated on with open and laparoscopic right-sided colectomy (cStages I-III) with a central lymphadenectomy at two Norwegian institutions between October 2016 and December 2021. Dissections were conducted along the superior mesenteric vein in the laparoscopic group, and along the left anterior border of the superior mesenteric artery in the open group, both according to complete mesocolic excision principles. Surgery was standardized and performed by three experienced surgeons for each study group. The primary outcome of interest was to measure postoperative 30-day complications (Clavien-Dindo ≥ grade II). RESULTS: Of 273 eligible patients, 135 were randomized and 128 analysed (63 operated on with open and 65 using laparoscopic procedures). Postoperative complications occurred in 42.8 per cent of the patients treated with open and 38.4 per cent of the patients treated using laparoscopic surgery, P = 0.372. The incidence of Clavien-Dindo grade IIIb complications was 7.9 per cent in the open versus 4.6 per cent in the laparoscopic group, P = 0.341. There were no grade IV or V complications, and no re-operations due to anastomotic leakages. There was no significant difference in the mean(s.e.m.) number of removed lymph nodes (open versus laparoscopic respectively: 31.9(1.8) versus 29.3(1.3); P = 0.235). CONCLUSION: There was no significant difference in complications between the two groups. Standardized oncologic right-sided colectomy with central lymphadenectomy along the mesenterial root was performed safely, both open and laparoscopic, with incidence of major complications ranging between 4.6 and 7.9 per cent and no re-operations for anastomotic leakage. Radicality in terms of lymphadenectomy was comparable between the two groups.Registration number: NCT03776591 (http://www.clinicaltrials.gov).

Long-Term Outcome in a Phase II Study of Regional Hyperthermia Added to Preoperative Radiochemotherapy in Locally Advanced and Recurrent Rectal Adenocarcinomas.

Hyperthermia was added to standard preoperative chemoradiation for rectal adenocarcinomas in a phase II study. Patients with T3-4 N0-2 M0 rectal cancer or local recurrences were included. Radiation dose was 54 Gy combined with capecitabine 825 mg/m2 × 2 daily and once weekly oxaliplatin 55 mg/m2. Regional hyperthermia aimed at 41.5-42.5 °C for 60 min combined with oxaliplatin infusion. Radical surgery with total or extended TME technique, was scheduled at 6-8 weeks after radiation. From April 2003 to April 2008, a total of 49 eligible patients were recruited. Median number of hyperthermia sessions were 5.4. A total of 47 out of 49 patients (96%) had the scheduled surgery, which was clinically radical in 44 patients. Complete tumour regression occurred in 29.8% of the patients who also exhibited statistically significantly better RFS and CSS. Rate of local recurrence alone at 10 years was 9.1%, distant metastases alone occurred in 25.6%, including local recurrences 40.4%. RFS for all patients was 54.8% after 5 years and CSS was 73.5%. Patients with T50 temperatures in tumours above median 39.9 °C had better RFS, 66.7% vs. 31.3%, p = 0.047, indicating a role of hyperthermia. Toxicity was acceptable.

Colorectal cancer incidence, mortality, and stage distribution in European countries in the colorectal cancer screening era: an international population-based study.

BACKGROUND: Colorectal cancer screening programmes and uptake vary substantially across Europe. We aimed to compare changes over time in colorectal cancer incidence, mortality, and stage distribution in relation to colorectal cancer screening implementation in European countries. METHODS: Data from nearly 3·1 million patients with colorectal cancer diagnosed from 2000 onwards (up to 2016 for most countries) were obtained from 21 European countries, and were used to analyse changes over time in age-standardised colorectal cancer incidence and stage distribution. The WHO mortality database was used to analyse changes over time in age-standardised colorectal cancer mortality over the same period for the 16 countries with nationwide data. Incidence rates were calculated for all sites of the colon and rectum combined, as well as the subsites proximal colon, distal colon, and rectum. Average annual percentage changes (AAPCs) in incidence and mortality were estimated and relevant patterns were descriptively analysed. FINDINGS: In countries with long-standing programmes of screening colonoscopy and faecal tests (ie, Austria, the Czech Republic, and Germany), colorectal cancer incidence decreased substantially over time, with AAPCs ranging from -2·5% (95% CI -2·8 to -2·2) to -1·6% (-2·0 to -1·2) in men and from -2·4% (-2·7 to -2·1) to -1·3% (-1·7 to -0·9) in women. In countries where screening programmes were implemented during the study period, age-standardised colorectal cancer incidence either remained stable or increased up to the year screening was implemented. AAPCs for these countries ranged from -0·2% (95% CI -1·4 to 1·0) to 1·5% (1·1 to 1·8) in men and from -0·5% (-1·7 to 0·6) to 1·2% (0·8 to 1·5) in women. Where high screening coverage and uptake were rapidly achieved (ie, Denmark, the Netherlands, and Slovenia), age-standardised incidence rates initially increased but then subsequently decreased. Conversely, colorectal cancer incidence increased in most countries where no large-scale screening programmes were available (eg, Bulgaria, Estonia, Norway, and Ukraine), with AAPCs ranging from 0·3% (95% CI 0·1 to 0·5) to 1·9% (1·2 to 2·6) in men and from 0·6% (0·4 to 0·8) to 1·1% (0·8 to 1·4) in women. The largest decreases in colorectal cancer mortality were seen in countries with long-standing screening programmes. INTERPRETATION: We observed divergent trends in colorectal cancer incidence, mortality, and stage distribution across European countries, which appear to be largely explained by different levels of colorectal cancer screening implementation. FUNDING: German Cancer Aid (Deutsche Krebshilfe) and the German Federal Ministry of Education and Research.

Evaluation of the stage classification of anal cancer by the TNM 8th version versus the TNM 7th version.

Background: The UICC TNM 7th edition introduced stage groups for anal cancer which in 2019 has not yet come into general use. The new TNM 8th edition from 2016 defines 7 sub-stages. Background data for these changes are lacking. We aimed to investigate whether the new classification for anal cancer reliably predict the prognosis in the different stages.Patients and methods: The Nordic Anal Cancer Group (NOAC) conducted a large retrospective study of all anal cancers in Norway, Sweden and most of Denmark in 2000-2007. From the Nordic cohort 1151 anal cancer patients with follow-up data were classified by the TNM 4th edition which has identical T, N and M definitions as the TNM 7th edition, and therefore also can be classified by the TNM 7th stage groups. We used the Nordic cohort to translate the T, N and M stages into the TNM 8th stages and sub-stages. Overall survival for each stage was assessed.Results: Although the summary stage groups for TNM 8th edition discriminates patients with different prognosis reasonably well, the analyses of the seven sub-stages show overlapping overall survival: HR for stage IIA 1.30 (95%CI 0.80-2.12) is not significantly different from stage I (p = .30) and HR for stage IIB 2.35 (95%CI 1.40-3.95) and IIIA 2.48 (95%CI 1.43-4.31) are also similar as were HRs for stage IIIB 3.41 (95%CI 1.99-5.85) and IIIC 3.22 (95%CI 1.99-5.20). Similar overlapping was shown for local recurrence and distant spread.Conclusion: The results for the sub-stages calls for a revision of the staging system. We propose a modification of the TNM 8th edition for staging of anal cancer into four stages based on the T, N and M definitions of the TNM 8th classification.

EFSUMB Recommendations for Gastrointestinal Ultrasound Part 3: Endorectal, Endoanal and Perineal Ultrasound.

This article represents part 3 of the EFSUMB Recommendations and Guidelines for Gastrointestinal Ultrasound (GIUS). It provides an overview of the examination techniques recommended by experts in the field of endorectal/endoanal ultrasound (ERUS/EAUS), as well as perineal ultrasound (PNUS). The most important indications are rectal tumors and inflammatory diseases like fistula and abscesses in patients with or without inflammatory bowel disease (IBD). PNUS sometimes is more flexible and convenient compared to ERUS. However, the technique of ERUS is quite well established, especially for the staging of rectal cancer. EAUS also gained ground in the evaluation of perianal diseases like fistulas, abscesses and incontinence. For the staging of perirectal tumors, the use of PNUS in addition to conventional ERUS could be recommended. For the staging of anal carcinomas, PNUS can be a good option because of the higher resolution. Both ERUS and PNUS are considered excellent guidance methods for invasive interventions, such as the drainage of fluids or targeted biopsy of tissue lesions. For abscess detection and evaluation, contrast-enhanced ultrasound (CEUS) also helps in therapy planning.

Endorectal ultrasound and magnetic resonance imaging for staging of early rectal cancers: how well does it work in practice?

BACKGROUND: Rectal tumor treatment strategies are individually tailored based on tumor stage, and yield different rates of posttreatment morbidity, mortality, and local recurrence. Therefore, the accuracy of pretreatment staging is highly important. Here we investigated the accuracy of staging by magnetic resonance imaging (MRI) and endorectal ultrasound (ERUS) in a clinical setting. MATERIAL AND METHODS: A total of 500 patients were examined at the rectal cancer outpatient clinic at Haukeland University Hospital between October 2014 and January 2018. This study included only cases in which the resection specimen had a histopathological staging of adenoma or early rectal cancer (pT1-pT2). Patients with previous pelvic surgery or preoperative radiotherapy were excluded. The 145 analyzed patients were preoperatively examined via biopsy (n = 132), digital rectal examination (n = 77), rigid rectoscopy (n = 127), ERUS (n = 104), real-time elastography (n = 96), and MRI (n = 84). RESULTS: ERUS distinguished between adenomas and early rectal cancer with 88% accuracy (95% CI: 0.68-0.96), while MRI achieved 75% accuracy (95% CI: 0.54-0.88). ERUS tended to overstage T1 tumors as T2-T3 (16/24). MRI overstaged most adenomas to T1-T2 tumors (18/22). Neither ERUS nor MRI distinguished between T1 and T2 tumors. CONCLUSIONS: In a clinical setting, ERUS differentiated between benign and malignant tumors with high accuracy. The present findings support previous reports that ERUS and MRI have low accuracy for T-staging of early rectal cancer. We recommend that MRI be routinely combined with ERUS for the clinical examination of rectal tumors, since MRI consistently overstaged adenomas as cancer. In adenomas, MRI had no additional benefit for preoperative staging.

Interobserver Analysis of CEUS-Derived Perfusion in Fibrotic and Inflammatory Crohn's Disease.

AIM: To examine if there are perfusion differences in fibrotic versus inflammatory lesions in patients with Crohn's disease (CD) and to assess the interobserver reliability of the analysis. MATERIALS AND METHODS: 37 patients with Crohn's disease were prospectively recruited. 20 were operated and 18 of them had fibrotic disease. 17 received and were mostly responsive to medical treatment (14/17). Each patient underwent clinical scoring and ultrasound (US) examination with high-frequency linear transducers and US contrast. The perfusion analysis was performed using exported DICOM videos with VueBox® (Bracco Suisse SA, Genève, Switzerland). The program fits the time-intensity data to a standardized curve, from which several parameters can be derived, such as amplitude-based peak enhancement (PE), total area under the curve (AUC), area under the curve during wash-in and wash-out (WiAUC and WoAUC), wash-in rate (WiR) and wash-out rate (WoR) and time-based rise time (RT), fall time (FT) and mean transit time (MTT). RESULTS: There was a significant difference between the groups for the parameters PE (p = 0.032), WiAUC (p = 0.035) and WoR (p = 0.038). We found no significant difference for RT, MTT, FT, WiR, AUC and WoAUC. An interobserver analysis showed correlation between two observers for all the parameters (r = 0.66 - 0.92, p < 0.001), except MTT (r = 0.46, p = 0.129). Bland Altman analysis revealed a fixed bias for the parameters PE, WiAUC and RT. CONCLUSION: The amplitude-based parameters PE, WiAUC and WoR could potentially be used to separate fibrotic and inflammatory lesions in patients suffering from CD due to significant differences and low interobserver variability.

Randomized Controlled Trial of Extended Perioperative Counseling in Enhanced Recovery After Colorectal Surgery.

BACKGROUND: Enhanced recovery after surgery programs reduce the length of hospital stay in patients who undergo elective colorectal resection, but the reasons for this reduction are not well understood. OBJECTIVE: The aim of this randomized controlled trial was to assess the impact of extended perioperative counseling in treatment groups that were otherwise the same with respect to enhanced recovery after surgery criteria. DESIGN: Patients eligible for open or laparoscopic colorectal resection were randomly assigned to extended counseling (repeated information and guidance by a dedicated nurse) or standard counseling. SETTINGS: This study was conducted at a single institution. PATIENTS: Patients (n = 164) were randomly assigned to enhanced recovery after surgery plus extended counseling (n = 80) or enhanced recovery after surgery with standard counseling (n = 84). MAIN OUTCOME MEASURES: The primary end point was the total length of hospital stay. Discharge criteria were defined. Secondary end points were postoperative complications, postoperative length of hospital stay, readmission rate, and mortality. RESULTS: Total hospital stay was significantly shorter among patients randomly assigned to enhanced recovery after surgery plus extended counseling (median 5 (range 2-29) days vs 7 (range 2-39) days, p < 0.001). The 2 treatment groups differed in adherence to the elements of postoperative enhanced recovery after surgery such as mobilization and total oral intake. The 2 treatment groups did not differ in overall, major, and minor morbidity; reoperation rate; readmission rate; and 30-day mortality. LIMITATIONS: The main limitation of this study was the absence of blinding. CONCLUSIONS: Perioperative information and guidance were important factors in enhanced recovery after surgery care and were associated with a significantly shorter length of hospital stay. Our findings suggest that perioperative counseling enables patients to comply with the elements of postoperative enhanced recovery after surgery and thereby reduces the length of hospital stay. This study was registered with ClinicalTrials.gov (NCT01610726). See Video Abstract at http://links.lww.com/DCR/A505.

Enhanced Recovery After Colorectal Surgery (ERAS) in Elderly Patients Is Feasible and Achieves Similar Results as in Younger Patients.

Aim: Enhanced recovery after surgery (ERAS) is a multimodal approach that aims to optimize perioperative treatment. Whether elderly patients receiving colorectal surgery can adhere to and benefit from an ERAS approach is uncertain. The aim of this study was to compare patients in different age groups participating in an ERAS program. Method: In this substudy of a randomized controlled trial, we analyzed the interventional ERAS arm of adult patients eligible for laparoscopic or open colorectal resection with regard to the importance of age. Patients were divided into three groups based on age: ≤65 years (n = 79), 66-79 years (n = 56), and ≥80 years (n = 19). The primary end point was total postoperative hospital stay (THS). Secondary end points were postoperative hospital stay, postoperative complications, postoperative C-reactive protein levels, readmission rate, mortality, and patient adherence to the different ERAS elements. All parameters and measuring the adherence to the ERAS protocol were recorded before surgery, on the day of the operation, and daily until discharge. Results: There were no significant differences in length of THS between age groups (≤65 years, median 5 [range 2-47] days; 66-79 years, median 5.5 [range 2-36] days; ≥80 years, median 7 [range 3-50] days; p = .53). All secondary outcomes were similar between age groups. Patient adherence to the ERAS protocol was as good in the elderly as it was in the younger patients. Conclusion: Elderly patients adhered to and benefited from an ERAS program, similar to their younger counterparts.

Multimodal therapy is feasible in elderly anal cancer patients.

BACKGROUND: Many patients are diagnosed with an anal cancer in high ages. We here present the outcome after oncological therapy for patients above 80 years compared with younger patients. MATERIALS AND METHODS: A series of 213 consecutive patients was diagnosed and treated at a single institution from 1984 to 2009. The patients received similar radiation doses but with different techniques, thus progressively sparing more normal tissues. The majority of patients also had simultaneous [5-fluorouracil (5FU) and mitomycin C] or induction chemotherapy (cisplatin and 5FU). The patients were stratified by age above or below 80 years. Despite that the goal was to offer standard chemoradiation treatment to all, the octo- and nonagenarians could not always be given chemotherapy. RESULTS: In our series 35 of 213 anal cancer patients were above 80 years. After initial therapy similar complete response was observed, 80% above and 87% below 80 years. Local recurrence rate was also similar in both groups, 21% versus 26% (p = .187). Cancer-specific survival and relative survival were significantly lower in patients above 80 years, 60% and 50% versus 83% and 80%, (p = .015 and p = .027), respectively. CONCLUSION: Patients older than 80 years develop anal cancer, but more often marginal tumors. Even in the oldest age group half of the patients can tolerate standard treatment by a combination of radiation and chemotherapy, and obtain a relative survival of 50% after five years. Fragile patients not considered candidates for chemoradiation may be offered radiation or resection to control local disease.

Nationwide implementation of laparoscopic surgery for colon cancer: short-term outcomes and long-term survival in a population-based cohort.

BACKGROUND: Randomized trials show similar outcomes after open surgery and laparoscopy for colon cancer, and confirmation of outcomes after implementation in routine practice is important. While some studies have reported long-term outcomes after laparoscopic surgery from single institutions, data from large patient cohorts are sparse. We investigated short- and long-term outcomes of laparoscopic and open surgery for treating colon cancer in a large national cohort. METHODS: We retrieved data from the Norwegian Colorectal Cancer Registry for all colon cancer resections performed in 2007-2010. Five-year relative survival rates following laparoscopic and open surgeries were calculated, including excess mortality rates associated with potential predictors of death. RESULTS: Among 8707 patients with colon cancer that underwent major resections, 16 % and 36 % received laparoscopic procedures in 2007 and 2010, respectively. Laparoscopic procedures were most common in elective surgeries for treating stages I-III, right colon, or sigmoid tumours. The conversion rate of laparoscopic procedures was 14.5 %. Among all patients, laparoscopy provided higher 5-year relative survival rates (70 %) than open surgery (62 %) (P = 0.040), but among the largest group of patients electively treated for stages I-III disease, the approaches provided similar relative survival rates (78 vs. 81 %; P = 0.535). Excess mortality at 2 years post-surgery was lower after laparoscopy than after open surgery (excess hazard ratio, 0.7; P = 0.013), but similar between groups during the last 3 years of follow-up. Major predictors of death were stage IV disease, tumour class pN+, age > 80 years, and emergency procedures (excess hazard ratios were 5.3, 2.4, 2.1, and 2.0, respectively; P < 0.001). CONCLUSION: Nationwide implementation of laparoscopic colectomy for colon cancer was safe and achieved results comparable to those from previous randomized trials.

Nationwide improvement of rectal cancer treatment outcomes in Norway, 1993-2010.

BACKGROUND: The Norwegian Rectal Cancer Project was initated in 1993 with the aims of improving surgery, decreasing local recurrence rates, improving survival, and establishing a national rectal cancer registry. Here we present results from the Norwegian Colorectal Cancer Registry (NCCR) from 1993 to 2010. MATERIAL AND METHODS: A total of 15 193 patients were diagnosed with rectal cancer in Norway 1993-2010, and were registered with clinical data regarding diagnosis, treatment, locoregional recurrences and distant metastases. Of these, 10 796 with non-metastatic disease underwent tumour resection. The results were stratified into five time periods, and the treatment outcomes were compared. Recurrence rates are presented for the 9785 patients who underwent curative major resection (R0/R1). RESULTS: Among all 15 193 patients, relative five-year survival increased from 54.1% in 1993-1997 to 63.4% in 2007-2010 (p < 0.001). Among the 10 796 patients with stage I-III disease who underwent tumour resection, from 1993-1997 to 2007-2010, relative five-year survival improved from 71.2% to 80.6% (p < 0.001). An increasing proportion of these patients underwent surgery at large-volume hospitals; and 30- and 100-day mortality rates, respectively, decreased from 3.0% to 1.4% (p < 0.001) and from 5.1% to 3.0% (p < 0.011). Use of preoperative chemoradiotherapy increased from 6.5% in 1993 to 39.0% in 2010 (p < 0.001). Estimated local recurrence rate after major resection (R0/R1) decreased from 14.5% in 1993-1997 to 5.0% in 2007-2009 (p < 0.001), and distant recurrence rate decreased from 26.0% to 20.2% (p < 0.001). CONCLUSION: Long-term outcomes from a national population-based rectal cancer registry are presented. Improvements in rectal cancer treatment have led to decreased recurrence rates of 5% and increased survival on a national level.

Validity of Norwegian Rectal Cancer Registry data at a major university hospital 1997-2005.

BACKGROUND: The Norwegian Rectal Cancer Registry (NRCR) has been used extensively to monitor patient treatment and outcomes since its establishment in 1993. Control of data validity is crucial to ensure reliable information, but an audit of the NRCR data validity has not been performed so far. This study aims to validate NRCR data on patients diagnosed in the period 1997-2005, Department of Surgery, Haukeland University Hospital. MATERIAL AND METHODS: The material comprises NRCR data on all 482 patients diagnosed with rectal cancer in the period 1997-2005 at a major Norwegian university hospital. We checked 50 variables for discrepancies by comparing NRCR data with the medical records. All erroneous registrations were recorded. RESULTS: One hundred patients (21%) had one or more data discrepancies in the registry, and 131 errors (0.5%) were noted in total. Sixteen variables (32%) had no erroneous registrations. Pre-operative CT and type of surgical procedure had the highest proportion of erroneous registrations (2.1%). Recorded errors were grouped into five variable categories: Pre-operative evaluation and adjuvant treatment (40 errors), surgical treatment (44 errors), pathological evaluation (20 errors), complications (7 errors) and oncological outcomes (20 errors). The majority of erroneous registrations (45%) were considered minor in severity, 27% were moderate and 28% were major. CONCLUSION: Assessment of the NRCR data from a nine-year period showed a good data validity in this hospital cohort.