IntroductionTotal mesorectal excision (TME) is the highly effective standard treatment for rectal cancer but is associated with significant morbidity and may be overtreatment for low-risk cancers. This study is designed to determine the feasibility of international recruitment in a study comparing organ-saving approaches versus standard TME surgery.Methods and analysisSTAR-TREC trial is a multicentre international randomised, three-arm parallel, phase II feasibility study in patients with biopsy-proven adenocarcinoma of the rectum. The trial is coordinated from Birmingham, UK with national hubs in Radboudumc (the Netherlands) and Odense University Hospital Svendborg UMC (Denmark). Patients with rectal cancer, staged by CT and MRI as ≤cT3b (up to 5 mm of extramural spread) N0 M0 can be included. Patients will be randomised to either standard TME surgery (control), organ-saving treatment using long-course concurrent chemoradiation or organ-saving treatment using short-course radiotherapy. For patients treated with an organ-saving strategy, clinical response to (chemo)radiotherapy determines the next treatment step. An active surveillance regime will be performed in the case of a complete clinical regression. In the case of incomplete clinical regression, patients will proceed to local excision using an optimised platform such as transanal endoscopic microsurgery or other transanal techniques (eg, transanal endoscopic operation or transanal minimally invasive surgery). The primary endpoint of this phase II study is to demonstrate sufficient international recruitment in order to sustain a phase III study incorporating pelvic failure as the primary endpoint. Success in phase II is defined as randomisation of at least four cases per month internationally in year 1, rising to at least six cases per month internationally during year 2.Ethics and disseminationThe medical ethical committees of all the participating countries have approved the study protocol. Results of the primary and secondary endpoints will be submitted for publication in peer-reviewed journals.Trial registration number
ISRCTN14240288, 20 October 2016. NCT02945566; Pre-results, October 2016.
a b s t r a c tBackground and purpose: Organ preservation strategies are increasingly being explored for early rectal cancer. This requires revision of target volumes according to disease stage, as well as new guidelines for treatment planning. We conducted an international, multicentre dose planning study to develop robust planning objectives for modern radiotherapy of a novel mesorectal-only target volume, as implemented in the STAR-TReC trial (NCT02945566). Materials and methods: The published literature was used to establish relevant dose levels for organ at risk (OAR) plan optimisation. Ten representative patients with early rectal cancer were identified. Treatment scans had mesorectal target volumes as well as bowel cavity, bladder and femoral heads outlined, and were circulated amongst the three participating institutions. Each institution produced plans for short course (SCRT, 5 Â 5 Gy) and long course (LCRT, 25 Â 2 Gy) treatment, using volumetric modulated arc therapy on different dose planning systems. Optimisation objectives for OARs were established by determining dose metric objectives achievable for !90% of plans. Results: Sixty plans, all fulfilling target coverage criteria, were produced. The planning results and literature review suggested optimisation objectives for SCRT: V 10Gy < 180 cm 3 , V 18Gy < 110 cm 3 , V 23Gy < 85 cm 3 for bowel cavity; V 21Gy < 15% and V 25Gy < 5% for bladder; and V 12.5Gy < 11% for femoral heads. Corresponding objectives for LCRT: V 20Gy < 180 cm 3 , V 30Gy < 130 cm 3 , V 45Gy < 90 cm 3 for bowel cavity; V 35Gy < 22% and V 50Gy < 7% for bladder; and V 25Gy < 15% for femoral heads. Constraints were validated across all three institutions. Conclusion: We utilized a multicentre planning study approach to develop robust planning objectives for mesorectal radiotherapy for early rectal cancer.
To enable in-vivo monitoring of Intensity Modulated Radiotherapy (IMRT) with minimal attenuation of the treatment field, an upstream camera system based on a Monolithic Active Pixel Sensor (MAPS) has been developed. This system has been used to precisely reconstruct the position of the Multileaf Collimators (MLC) that are used to shape the treatment field. The results show the position of a MLC is known with a precision of 6 {tm with 10 seconds worth of data and 52 ± 4 {tm for a single frame.
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