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Introduction Inadequate treatment of enlarged lateral lymph nodes (LLNs) in rectal cancer patients is associated with an increased lateral local recurrence (LLR) risk, despite neoadjuvant treatment and total mesorectal excision (TME) surgery. There is a promising role for LLN dissection (LLND) to lower this risk, but this challenging procedure requires appropriate training. This study protocol describes a prospective evaluation of oncological outcomes after standardised treatment based on multidisciplinary training, thereby aiming for a 50% reduction in LLR rate.Methods and analysis A prospective registration study will be opened in hospitals in which the involved multidisciplinary team members (radiologists, radiation oncologists, surgeons and pathologists) have received dedicated training to enhance knowledge and awareness of LLNs and in which standardised treatment including LLND has been implemented. Patients with rectal cancer and at least one enlarged LLN (short-axis ≥7.0 mm), or intermediate LLN (short-axis 5.0–6.9 mm) with at least one malignant feature on primary MRI, evaluated by a trained radiologist, are eligible. Patients will undergo neoadjuvant treatment by trained radiation oncologists, followed by TME surgery in combination with a minimally invasive, nerve-sparing LLND performed by trained surgeons. LLND specimens are evaluated by trained pathologists or grossing assistants. The primary outcome is LLR rate 3 years postoperatively. Secondary outcomes are morbidity, disease-free survival, overall survival and quality of life. To demonstrate a significant reduction in LLR rate from 13% (based on historical control data) to 6% after optimised treatment, 200 patients with enlarged LLNs are required.Ethics and dissemination The medical ethics board of the Vrije Universiteit Medical Centre (VUMC), the Netherlands, approved the study on 23 November 2022 (reference: 2021.0524). Participating centres must obtain local approval and participants are required to provide written informed consent. Results obtained from this study will be communicated via peer-reviewed medical journals and presentations at conferences.Trail registration number NCT04486131, 24 July 2020, https://clinicaltrials.gov/ct2/show/NCT04486131.

Background and purpose: In rectal cancer patients, radiotherapy in prone position using a belly board can reduce the dose to organs at risk. For this patient group we investigated inter-fraction shape variation of the mesorectal part of the clinical target volume (CTV) and determined planning target volume (PTV) margins. Materials and methods: Patients with rectal cancer receiving neoadjuvant (chemo)radiotherapy were eligible. For each patient a planning computed tomography (pCT) and five cone-beam CT (CBCT) scans were acquired in prone position using a belly board. The mesorectal CTV was delineated on all scans. Mesorectal shape variation was quantified relative to the pCT. PTV margins were derived locally and averaged for separate subregions of the mesorectal CTV. For each patient a total PTV was constructed using our clinical margins for mesorectal and lymph node CTVs. An artificial dose distribution conforming to this PTV was used to calculate the coverage for the mesorectal CTV using the CBCT delineations. Results: In 19 rectal cancer patients the derived PTV margins were smallest in the upper-lateral region (6 mm) and largest in the upper-anterior region (16 mm). PTV margins for the upper-anterior region were larger for female patients (19 mm) compared to male patients (14 mm). Clinical margins for the total PTV were sufficient for a coverage of at least 97% of the mesorectal CTV for all patients. Conclusions: Mesorectal shape variation is heterogeneous and largest in the upper-anterior region, in rectal cancer patients irradiated in prone position and using a belly board.

Abstract Background The STAR-TReC trial is an international multi-center, randomized, phase II study assessing the feasibility of short-course radiotherapy or long-course chemoradiotherapy as an alternative to total mesorectal excision surgery. A new target volume is used for both (chemo)radiotherapy arms which includes only the mesorectum. The treatment planning QA revealed substantial variation in dose to organs at risk (OAR) between centers. Therefore, the aim of this study was to determine the treatment plan variability in terms of dose to OAR and assess the effect of a national study group meeting on the quality and variability of treatment plans for mesorectum-only planning for rectal cancer. Methods Eight centers produced 25 × 2 Gy treatment plans for five cases. The OAR were the bowel cavity, bladder and femoral heads. A study group meeting for the participating centers was organized to discuss the planning results. At the meeting, the values of the treatment plan DVH parameters were distributed among centers so that results could be compared. Subsequently, the centers were invited to perform replanning if they considered this to be necessary. Results All treatment plans, both initial planning and replanning, fulfilled the target constraints. Dose to OAR varied considerably for the initial planning, especially for dose levels below 20 Gy, indicating that there was room for trade-offs between the defined OAR. Five centers performed replanning for all cases. One center did not perform replanning at all and two centers performed replanning on two and three cases, respectively. On average, replanning reduced the bowel cavity V20Gy by 12.6%, bowel cavity V10Gy by 22.0%, bladder V35Gy by 14.7% and bladder V10Gy by 10.8%. In 26/30 replanned cases the V10Gy of both the bowel cavity and bladder was lower, indicating an overall lower dose to these OAR instead of a different trade-off. In addition, the bowel cavity V10Gy and V20Gy showed more similarity between centers. Conclusions Dose to OAR varied considerably between centers, especially for dose levels below 20 Gy. The study group meeting and the distribution of the initial planning results among centers resulted in lower dose to the defined OAR and reduced variability between centers after replanning. Trial registration The STAR-TReC trial, ClinicalTrials.gov Identifier: NCT02945566. Registered 26 October 2016, https://clinicaltrials.gov/ct2/show/NCT02945566 ).

Purpose: To analyze recurrence patterns in patients with cancer of the esophagus or gastroesophageal junction treated with either preoperative chemoradiotherapy (CRT) plus surgery or surgery alone., Patients and Methods: Recurrence pattern was analyzed in patients from the previously published CROSS I and II trials in relation to radiation target volumes. CRT consisted of five weekly courses of paclitaxel and carboplatin combined with a concurrent radiation dose of 41.4 Gy in 1.8-Gy fractions to the tumor and pathologic lymph nodes with margin., Results: Of the 422 patients included from 2001 to 2008, 418 were available for analysis. Histology was mostly adenocarcinoma (75%). Of the 374 patients who underwent resection, 86% were allocated to surgery and 92% to CRT plus surgery. On January 1, 2011, after a minimum follow-up of 24 months (median, 45 months), the overall recurrence rate in the surgery arm was 58% versus 35% in the CRT plus surgery arm. Preoperative CRT reduced locoregional recurrence (LRR) from 34% to 14% (P < .001) and peritoneal carcinomatosis from 14% to 4% (P < .001). There was a small but significant effect on hematogenous dissemination in favor of the CRT group (35% v 29%; P = .025). LRR occurred in 5% within the target volume, in 2% in the margins, and in 6% outside the radiation target volume. In 1%, the exact site in relation to the target volume was unclear. Only 1% had an isolated infield recurrence after CRT plus surgery., Conclusion: Preoperative CRT in patients with esophageal cancer reduced LRR and peritoneal carcinomatosis. Recurrence within the radiation target volume occurred in only 5%, mostly combined with outfield failures.