Effects of a perioperative educational pathway on ostomy self-care, level of independence and need for visiting nurse services: a comparative observational cohort study.

AIM: Most new ostomy patients are not able to manage ostomy self-care when they are discharged and rely on visiting nurse services for ostomy care. The aim of this study was to determine if a perioperative ostomy educational pathway increases the level of independence and decreases the need for visiting nurse services in new ostomy patients. METHOD: A prospective longitudinal study was conducted between July 2018 and February 2020. Patients who received a colostomy or ileostomy and were treated on the surgery ward were included. Patients who followed a perioperative ostomy educational pathway were compared to a historical control group. The primary outcome measure was the level of independence in ostomy care and the need for visiting nurse services. RESULTS: After discharge, 67.6% of patients in the intervention group (n = 244) were able to independently perform ostomy care and were therefore not relying on visiting nurse services, compared to 15.2% of the patients in the control group (n = 33). The need for visiting nurse services was higher in patients aged ≥70 years (OR 3.20, P < 0.001), those who did not attend the preoperative practice session (OR 3.02, P = 0.002), those with a history of transient ischaemic attack (OR 10.22, P = 0.045) and those with mild cognitive impairment (OR 28.98, P = 0.002). CONCLUSION: A perioperative ostomy educational pathway effectively increased the level of independence and decreased the need for visiting nurse services in new ostomy patients.

Post-operative complications following dose adaptation of intra-operative electron beam radiation therapy in locally advanced or recurrent rectal cancer.

Purpose: The benefit of intra-operative radiotherapy (IORT) in the treatment of locally advanced rectal cancer (LARC) or locally recurrent rectal cancer (LRRC) lie in its ability to provide high-dose of radiation to limited at-risk volume, thereby eliminating microscopic disease and decreasing toxicity. A comparative study between high-dose-rate (HDR) brachytherapy, named intra-operative brachytherapy (IOBT), and intra-operative electron radiotherapy (IOERT) was performed showing favorable LRFS after IOBT, possibly due to a higher surface dose that is inherent in IOBT technique. The IOERT technique in Catharina Hospital Eindhoven was adapted to increase the surface dose, aiming to improve local control. Post-operative complications due to an increased radiation dose remain the matter of concern. This retrospective study was performed to compare complication rates before and after adapted IOERT dose. Material and methods: All patients undergoing surgery with IOERT for LARC or LRRC from September 2019 until July 2023, were considered. Patients selected until August 31, 2021 were included in control cohort (n = 108), and those chosen from September 1, 2021 onwards were included in intervention cohort (n = 92). Perioperative and (major) post-operative complications were classified retrospectively, during admission, at 30 days, and at 90 days. Results: In LARC patients, a decrease in post-operative complications was observed (p = 0.009). 19% of LARC patients experienced major post-operative surgical complications, i.e., Clavien-Dindo grade 3b-5, regardless of treatment group. No difference in major 90-day complications was noted (p = 0.142). In LRRC patients, the use of induction chemotherapy decreased from 78% to 29% (p < 0.001), which complicated comparison. However, no difference in major post-operative complications was observed at 30 days (p = 0.222) or 90 days (p = 0.977) after surgery. Conclusions: Increased surface dose of IOERT does not seem to lead to an increase in post-operative complications. Further research is needed to evaluate the efficacy of dose adaptation in IOERT to improve local oncological control rates. Routine evaluation of CTCAE scores in follow-up will help uncover possible long-term radiation-induced toxicity.

Dutch national guidelines for locally recurrent rectal cancer.

Due to improvements in treatment for primary rectal cancer, the incidence of LRRC has decreased. However, 6-12% of patients will still develop a local recurrence. Treatment of patients with LRRC can be challenging, because of complex and heterogeneous disease presentation and scarce - often low-grade - data steering clinical decisions. Previous consensus guidelines have provided some direction regarding diagnosis and treatment, but no comprehensive guidelines encompassing all aspects of the clinical management of patients with LRRC are available to date. The treatment of LRRC requires a multidisciplinary approach and overarching expertise in all domains. This broad expertise is often limited to specific expert centres, with dedicated multidisciplinary teams treating LRRC. A comprehensive, narrative literature review was performed and used to develop the Dutch National Guideline for management of LRRC, in an attempt to guide decision making for clinicians, regarding the complete clinical pathway from diagnosis to surgery.

The Additional Role of F18-FDG PET/CT in Characterizing MRI-Diagnosed Tumor Deposits in Locally Advanced Rectal Cancer.

Rationale: F18-FDG PET/CT may be helpful in baseline staging of patients with high-risk LARC presenting with vascular tumor deposits (TDs), in addition to standard pelvic MRI and CT staging. Methods: All patients with locally advanced rectal cancer that had TDs on their baseline MRI of the pelvis and had a baseline F18-FDG PET/CT between May 2016 and December 2020 were included in this retrospective study. TDs as well as lymph nodes identified on pelvic MRI were correlated to the corresponding nodular structures on a standard F18-FDG PET/CT, including measurements of nodular SUVmax and SUVmean. In addition, the effects of partial volume and spill-in on SUV measurements were studied. Results: A total number of 62 patients were included, in which 198 TDs were identified as well as 106 lymph nodes (both normal and metastatic). After ruling out partial volume effects and spill-in, 23 nodular structures remained that allowed for reliable measurement of SUVmax: 19 TDs and 4 LNs. The median SUVmax between TDs and LNs was not significantly different (p = 0.096): 4.6 (range 0.8 to 11.3) versus 2.8 (range 1.9 to 3.9). For the median SUVmean, there was a trend towards a significant difference (p = 0.08): 3.9 (range 0.7 to 7.8) versus 2.3 (range 1.5 to 3.4). Most nodular structures showing either an SUVmax or SUVmean ≥ 4 were characterized as TDs on MRI, while only two were characterized as LNs. Conclusions: SUV measurements may help in separating TDs from lymph node metastases or normal lymph nodes in patients with high-risk LARC.

Factors associated with one-year mortality after curative surgery for primary clinical T4 and locally recurrent rectal cancer in elderly patients.

INTRODUCTION: Despite advancements in colorectal cancer care, one-year post-operative mortality rates remain high for elderly patients who have undergone curative surgery for primary clinical T4 rectal cancer (cT4RC) or locally recurrent rectal cancer (LRRC). This study aimed to identify factors associated with one-year mortality and to evaluate the causes of death. MATERIALS & METHODS: This retrospective cohort study included patients aged ≥70 years who underwent surgery with curative intent for cT4RC or LRRC between January 2013 and December 2020. Clinical and follow-up data were collected and analyzed to determine survival rates and investigate factors associated with mortality within one year after surgery. RESULTS: A total of 183 patients (94 cT4RC, 89 LRRC) were included. One-year mortality rates were 16.0% for cT4RC and 28.1% for LRRC (P = 0.064). In cT4RC patients, factors associated with one-year mortality were preoperative anemia (OR 3.83, P = 0.032), total pelvic exenteration (TPE) (OR 7.18, P = 0.018), multivisceral resections (OR 5.73, P = 0.028), pulmonary complications (OR 13.31, P < 0.001) and Clavien-Dindo grade ≥ III complications (OR 5.19, P = 0.025). In LRRC patients, factors associated with one-year mortality were TPE (OR 27.00, P = 0.008), the need for supported care after discharge (OR 3.93, P = 0.041) and Clavien-Dindo grade ≥ III complications (OR 3.95, P = 0.006). The main causes of death in cT4RC and LRRC patients were failure to recover (cT4RC 26.6%, LRRC 28.0%) and disease recurrence (cT4RC 26.6%, LRRC 60.0%). CONCLUSION: In order to tailor treatment in elderly with cT4RC and LRRC, factors associated with increased one-year mortality (e.g. pre-operative anemia, TPE) should be incorporated in the decision-making process. CLINICAL TRIAL REGISTRATION: Not applicable.

Optimisation of Organ Preservation treatment strategies in patients with rectal cancer with a good clinical response after neoadjuvant (chemo)radiotherapy: Additional contact X-ray brachytherapy versus eXtending the observation period and local excision (OPAXX) - protocol for two multicentre, parallel, single-arm, phase II studies.

INTRODUCTION: Standard treatment for patients with intermediate or locally advanced rectal cancer is (chemo)radiotherapy followed by total mesorectal excision (TME) surgery. In recent years, organ preservation aiming at improving quality of life has been explored. Patients with a complete clinical response to (chemo)radiotherapy can be managed safely with a watch-and-wait approach. However, the optimal organ-preserving treatment strategy for patients with a good, but not complete clinical response remains unclear. The aim of the OPAXX study is to determine the rate of organ preservation that can be achieved in patients with rectal cancer with a good clinical response after neoadjuvant (chemo)radiotherapy by additional local treatment options. METHODS AND ANALYSIS: The OPAXX study is a Dutch multicentre study that investigates the efficacy of two additional local treatments aiming at organ preservation in patients with a good, but not complete response to neoadjuvant treatment (ie near-complete response or a small residual tumour mass <3 cm). The sample size will be 168 patients in total. Patients will be randomised (1:1) between two parallel single-arm phase II studies: study arm 1 involves additional contact X-ray brachytherapy (an intraluminal radiation boost), while in study arm 2 the observation period is extended followed by a second response evaluation and optional transanal local excision. The primary endpoint of the study is the rate of successful organ preservation at 1 year following randomisation. Secondary endpoints include toxicity, morbidity, oncological and functional outcomes at 1 and 2 years of follow-up. Finally, an observational cohort study for patients who are not eligible for randomisation is conducted. ETHICS AND DISSEMINATION: The trial protocol has been approved by the medical ethics committee of the Netherlands Cancer Institute (METC20.1276/M20PAX). Informed consent will be obtained from all participants. The trial results will be published in an international peer-reviewed journal. TRIAL REGISTRATION NUMBER: NCT05772923.

An evaluation of postoperative outcomes and treatment changes after frailty screening and geriatric assessment and management in a cohort of older patients with colorectal cancer.

INTRODUCTION: Adequate patient selection is crucial within the treatment of older patients with colorectal cancer (CRC). While previous studies report increased morbidity and mortality in older patients screened positive for frailty, improvements in the perioperative care and postoperative outcomes have raised the question of whether older patients screened positive for frailty still face worse outcomes. This study aimed to investigate the postoperative outcomes of older patients with CRC screened positive for frailty, and to evaluate changes in treatment after frailty screening and geriatric assessment. MATERIALS AND METHODS: Patients ≥70 years with primary CRC who underwent frailty screening between 1 January 2019 and 31 October 2021 were included. Frailty screening was performed by the Geriatric-8 (G8) screening tool. If the G8 indicated frailty (G8 ≤ 14), patients were referred for a comprehensive geriatric assessment (CGA). Postoperative outcomes and changes in treatment based on frailty screening and CGA were evaluated. RESULTS: A total of 170 patients were included, of whom 74 (43.5%) screened positive for frailty (G8 ≤ 14). Based on the CGA, the initially proposed treatment plan was altered to a less intensive regimen in five (8.9%) patients, and to a more intensive regimen in one (1.8%) patient. Surgery was performed in 87.8% of patients with G8 ≤ 14 and 96.9% of patients with G8 > 14 (p = 0.03). Overall postoperative complications were similar between patients with G8 ≤ 14 and G8 > 14 (46.2% vs. 47.3%, p = 0.89). Postoperative delirium was observed in 7.7% of patients with G8 ≤ 14 and 1.1% of patients with G8 > 14 (p = 0.08). No differences in 30-day mortality (1.1% vs. 1.5%, p > 0.99) or one-year and two-year survival rates were observed (log rank, p = 0.26). DISCUSSION: Although patients screened positive for frailty underwent CRC surgery less often, those considered eligible for surgery can safely undergo CRC resection within current clinical care pathways, without increased morbidity and mortality. Efforts to optimise perioperative care and minimise the risk of postoperative complications, in particular delirium, seem warranted. A multidisciplinary onco-geriatric pathway may support tailored decision-making in patients at risk of frailty.

A Deep Learning Framework with Explainability for the Prediction of Lateral Locoregional Recurrences in Rectal Cancer Patients with Suspicious Lateral Lymph Nodes.

Malignant lateral lymph nodes (LLNs) in low, locally advanced rectal cancer can cause (ipsi-lateral) local recurrences ((L)LR). Accurate identification is, therefore, essential. This study explored LLN features to create an artificial intelligence prediction model, estimating the risk of (L)LR. This retrospective multicentre cohort study examined 196 patients diagnosed with rectal cancer between 2008 and 2020 from three tertiary centres in the Netherlands. Primary and restaging T2W magnetic resonance imaging and clinical features were used. Visible LLNs were segmented and used for a multi-channel convolutional neural network. A deep learning model was developed and trained for the prediction of (L)LR according to malignant LLNs. Combined imaging and clinical features resulted in AUCs of 0.78 and 0.80 for LR and LLR, respectively. The sensitivity and specificity were 85.7% and 67.6%, respectively. Class activation map explainability methods were applied and consistently identified the same high-risk regions with structural similarity indices ranging from 0.772-0.930. This model resulted in good predictive value for (L)LR rates and can form the basis of future auto-segmentation programs to assist in the identification of high-risk patients and the development of risk stratification models.

Implementation of an Enhanced Recovery after Surgery Protocol in Advanced and Recurrent Rectal Cancer Patients after beyond Total Mesorectal Excision Surgery: A Feasibility Study.

INTRODUCTION: The implementation of an Enhanced Recovery After Surgery (ERAS) protocol in patients with locally advanced rectal cancer (LARC) and locally recurrent rectal cancer (LRRC) has been deemed unfeasible until now because of the heterogeneity of this disease and low caseloads. Since evidence and experience with ERAS principles in colorectal cancer care are increasing, a modified ERAS protocol for this specific group has been developed. The aim of this study is to evaluate the implementation of a tailored ERAS protocol for patients with LARC or LRRC, requiring beyond total mesorectal excision (bTME) surgery. METHODS: Patients who underwent a bTME for LARC or LRRC between October 2021 and December 2022 were prospectively studied. All patients were treated in accordance with the ERAS LARRC protocol, which consisted of 39 ERAS care elements specifically developed for patients with LARC and LRRC. One of the most important adaptations of this protocol was the anaesthesia procedure, which involved the use of total intravenous anaesthesia with intravenous (iv) lidocaine, iv methadone, and iv ketamine instead of epidural anaesthesia. The outcomes showed compliance with ERAS care elements, complications, length of stay, and functional recovery. A follow-up was performed at 30 and 90 days post-surgery. RESULTS: Seventy-two patients were selected, all of whom underwent bTME for either LARC (54.2%) or LRRC (45.8%). Total compliance with the adjusted ERAS protocol was 73.6%. Major complications were present in 12 patients (16.7%), and the median length of hospital stay was 9 days (IQR 6.0-14.0). Patients who received multimodal anaesthesia (75.0%) stayed in the hospital for a median of 7.0 days (IQR 6.8-15.5). These patients received fewer opioids on the first three postoperative days than patients who received epidural analgesia (p < 0.001). CONCLUSIONS: The implementation of the ERAS LARRC protocol seemed successful according to its compliance rate of >70%. Its complication rate was substantially reduced in comparison with the literature. Multimodal anaesthesia is feasible in beyond TME surgery with promising effects on recovery after surgery.

Evaluation of National Surgical Practice for Lateral Lymph Nodes in Rectal Cancer in an Untrained Setting.

BACKGROUND: Involved lateral lymph nodes (LLNs) have been associated with increased local recurrence (LR) and ipsi-lateral LR (LLR) rates. However, consensus regarding the indication and type of surgical treatment for suspicious LLNs is lacking. This study evaluated the surgical treatment of LLNs in an untrained setting at a national level. METHODS: Patients who underwent additional LLN surgery were selected from a national cross-sectional cohort study regarding patients undergoing rectal cancer surgery in 69 Dutch hospitals in 2016. LLN surgery consisted of either 'node-picking' (the removal of an individual LLN) or 'partial regional node dissection' (PRND; an incomplete resection of the LLN area). For all patients with primarily enlarged (≥7 mm) LLNs, those undergoing rectal surgery with an additional LLN procedure were compared to those  undergoing only rectal resection. RESULTS: Out of 3057 patients, 64 underwent additional LLN surgery, with 4-year LR and LLR rates of 26% and 15%, respectively. Forty-eight patients (75%) had enlarged LLNs, with corresponding recurrence rates of 26% and 19%, respectively. Node-picking (n = 40) resulted in a 20% 4-year LLR, and a 14% LLR after PRND (n = 8; p = 0.677). Multivariable analysis of 158 patients with enlarged LLNs undergoing additional LLN surgery (n = 48) or rectal resection alone (n = 110) showed no significant association of LLN surgery with 4-year LR or LLR, but suggested higher recurrence risks after LLN surgery (LR: hazard ratio [HR] 1.5, 95% confidence interval [CI] 0.7-3.2, p = 0.264; LLR: HR 1.9, 95% CI 0.2-2.5, p = 0.874). CONCLUSION: Evaluation of Dutch practice in 2016 revealed that approximately one-third of patients with primarily enlarged LLNs underwent surgical treatment, mostly consisting of node-picking. Recurrence rates were not significantly affected by LLN surgery, but did suggest worse outcomes. Outcomes of LLN surgery after adequate training requires further research.

Locally recurrent rectal cancer: Oncological outcomes for patients with a pathological complete response after neoadjuvant therapy.

BACKGROUND: For patients with locally recurrent rectal cancer, it is an ongoing pursuit to establish factors predicting or improving oncological outcomes. In locally advanced rectal cancer, a pCR appears to be associated with improved outcomes. The aim of this retrospective cohort study was to compare the oncological outcomes of patients with locally recurrent rectal cancer with and without a pCR. METHODS: Patients who underwent neoadjuvant treatment and surgery for locally recurrent rectal cancer with curative intent between January 2004 and June 2020 at a tertiary referral hospital were analysed. Primary outcomes included overall survival, disease-free survival, metastasis-free survival, and local re-recurrence-free survival, stratified according to whether the patient had a pCR. RESULTS: Of a total of 345 patients, 51 (14.8 per cent) had a pCR. Median follow-up was 36 (i.q.r. 16-60) months. The 3-year overall survival rate was 77 per cent for patients with a pCR and 51.1 per cent for those without (P < 0.001). The 3-year disease-free survival rate was 56 per cent for patients with a pCR and 26.1 per cent for those without (P < 0.001). The 3-year local re-recurrence-free survival rate was 82 and 44 per cent respectively (P < 0.001). Surgical procedures (for example soft tissue, sacrum, and urogenital organ resections) and postoperative complications were comparable between patients with and without a pCR. CONCLUSION: This study showed that patients with a pCR have superior oncological outcomes to those without a pCR. It may therefore be safe to consider a watch-and-wait approach in highly selected patients, potentially improving quality of life by omitting extensive surgical procedures without compromising oncological outcomes.

The development and implementation of an interactive application for new ostomy patients.

AIM: Guidance throughout the entire process of ostomy surgery is warranted to improve self-management and reduce healthcare consumption. The aim of this study was to develop an interactive application to educate patients scheduled for ostomy surgery and to evaluate patient satisfaction and implementation. METHOD: A literature study and a cross-sectional study among patients and nurses was performed to evaluate the relevance of different topics (e.g., ostomy materials, self-care, complications, impact) for an interactive application in ostomy surgery. The interactive application, StoManager, was developed in collaboration with patients and healthcare providers. The implementation of the application was evaluated among 30 patients scheduled for ostomy surgery to investigate usability, patient satisfaction, compliance, the need for home nursing care services, and the number of contact moments with the ostomy nurse. RESULTS: StoManager contained all topics considered relevant by patients and healthcare providers, including information on ostomy surgery, ostomy self-care and ostomy-related complications. Patient-reported outcome measures were incorporated to monitor the patient's health status during treatment. The usability scores of StoManager were above average. Patients rated StoManager with an overall score of 7.5 (SD 1.5) out of 10. The response rate to the patient-reported outcome measures was 79.3%. At discharge, 28/30 (93.3%) patients did not need home nursing care services for ostomy care. CONCLUSIONS: An interactive application to support patients throughout the entire process of ostomy surgery is feasible. Patients were satisfied with StoManager and its usability, which might result in improved self-management and decreased healthcare consumption. A more patient-specific approach could further improve the perceived quality and value of the application.

Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy with Intra-Operative Radiotherapy for Patients with Locally Advanced or Locally Recurrent Rectal Cancer and Peritoneal Metastases.

Purpose: To assess the safety and long-term outcome of a multimodality treatment consisting of radical surgery, intra-operative radiotherapy (IORT), and cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) for patients with locally advanced rectal cancer (LARC) or locally recurrent rectal carcinoma (LRRC) and peritoneal metastases (PM). Methods: The present study was a single-center cohort study, including all consecutive patients undergoing this treatment in a tertiary referral center for LARC, LRRC, and PM. Postoperative complications, intensive care stay (ICU stay), and re-admission rates were assessed as well as disease-free survival (DFS) and overall survival (OS). Results: A total of 14 LARC and 16 LRRC patients with PM were included in the study. The median ICU stay was 1 day, and 57% of patients developed a severe postoperative complication. No 90-day mortality was observed. Median DFS was 10.0 months (Interquartile Range 7.1-38.7), and median OS was 31.0 months (Interquartile Range 15.9-144.3). Conclusions: As postoperative complications and survival were in line with treatments that are accepted for LARC or LRRC and PM as separate procedures, we conclude that combined treatment with IORT and CRS-HIPEC should be considered as a treatment option for selected patients with LARC or LRRC and peritoneal metastases in tertiary referral centers.

Prognosis of mucinous colon cancer is determined by histological biomarkers rather than microsatellite instability.

The prognostic value of microsatellite instability (MSI), as well as other histological characteristics such as lymphovascular invasion (LI), perineural invasion (PNI) and extramural vascular invasion (EMVI), is unclear in colorectal mucinous carcinoma (MC). This study aims to determine the relevance of these factors in MC patients and analyses the role of MSI in stage III MC patients treated with adjuvant chemotherapy. A cohort of 650 patients diagnosed with stages I-IV colonic MC from 2000 to 2010 was selected from PALGA, the nationwide Dutch pathology databank. Histopathology was revised and mismatch repair (MMR) status determined. Univariate and multivariate survival analyses were performed. Deficient MMR (dMMR) was found in 33% of MCs and correlated with female gender and right-sidedness, but also with lower tumour stage (stages I/II: 73.2 versus 47%; P < 0.0001) and the absence of EMVI (9.7 versus 23.7%; P < 0.0001) and PNI (5.6 versus 12.7%; P = 0.005). On univariate analysis OS was better for dMMR MC than for proficient MMR (pMMR) MC (median OS of 9.7 versus 5.0 years; P = 0.009), but MMR status was no longer a relevant prognostic factor on multivariate analysis [hazard ratio (HR) = 0.91, 95% confidence interval (CI) = 0.70-1.18]. Stage III MC patients benefited from adjuvant chemotherapy, and dMMR status was associated with better OS in this group (HR = 0.35, 95% CI = 0.13-0.94). EMVI, LI and PNI, but not MMR, status are independent prognostic factors for survival in MC patients. Stage III MC patients benefit from adjuvant chemotherapy and dMMR status is associated with improved survival when adjuvant chemotherapy is given.

Development of a consensus-based delineation guideline for locally recurrent rectal cancer.

BACKGROUND AND PURPOSE: Neoadjuvant chemoradiotherapy (nCRT) is used in locally recurrent rectal cancer (LRRC) to increase chances of a radical surgical resection. Delineation in LRRC is hampered by complex disease presentation and limited clinical exposure. Within the PelvEx II trial, evaluating the benefit of chemotherapy preceding nCRT for LRRC, a delineation guideline was developed by an expert LRRC team. MATERIALS AND METHODS: Eight radiation oncologists, from Dutch and Swedish expert centres, participated in two meetings, delineating GTV and CTV in six cases. Regions at-risk for re-recurrence or irradical resection were identified by eleven expert surgeons and one expert radiologist. Target volumes were evaluated multidisciplinary. Inter-observer variation was analysed. RESULTS: Inter-observer variation in delineation of LRRC appeared large. Multidisciplinary evaluation per case is beneficial in determining target volumes. The following consensus regarding target volumes was reached. GTV should encompass all tumour, including extension into OAR if applicable. If the tumour is in fibrosis, GTV should encompass the entire fibrotic area. Only if tumour can clearly be distinguished from fibrosis, GTV may be reduced, as long as the entire fibrotic area is covered by the CTV. CTV is GTV with a 1 cm margin and should encompass all at-risk regions for irradical resection or re-recurrence. CTV should not be adjusted towards other organs. Multifocal recurrences should be encompassed in one CTV. Elective nodal delineation is only advised in radiotherapy-naïve patients. CONCLUSION: This study provides a first consensus-based delineation guideline for LRRC. Analyses of re-recurrences is needed to understand disease behaviour and to optimize delineation guidelines accordingly.

Narrowing the difference in dose delivery for IOERT and IOBT for locally advanced and locally recurrent rectal cancer.

Purpose: Intra-operative radiotherapy (IORT) has been used as a tool to provide a high-dose radiation boost to a limited volume of patients with fixed tumors with a likelihood of microscopically involved resection margins, in order to improve local control. Two main techniques to deliver IORT include high-dose-rate (HDR) brachytherapy, termed 'intra-operative brachytherapy' (IOBT), and electrons, termed 'intra-operative electron radiotherapy' (IOERT), both having very different dose distributions. A recent paper described an improved local recurrence-free survival favoring IOBT over IOERT for patients with locally advanced or recurrent rectal cancer and microscopically irradical resections. Although several factors may have contributed to this result, an important difference between the two techniques was the higher surface dose delivered by IOBT. This article described an adaptation of IOERT technique to achieve a comparable surface dose as dose delivered by IOBT. Material and methods: Two steps were taken to increase the surface dose for IOERT: 1. Introducing a bolus to achieve a maximum dose on the surface, and 2. Re-normalizing to allow for the same prescribed dose at reference depth. Conclusions: We describe and propose an adaptation of IOERT technique to increase surface dose, decreasing the differences between these two techniques, with the aim of further improving local control. In addition, an alternative method of dose prescription is suggested, to consider improved comparison with other techniques in the future.