A randomized phase III trial of structured tumour response surveillance and shared decision-making for organ...

Standard management with chemoradiotherapy (CRT) or total neoadjuvant therapy (TNT) followed by total mesorectal excision (TME) reduces local recurrence but often is associated with significant long-term functional impairment. Organ preservation (OP) has become a key therapeutic goal in rectal cancer to reduce surgery-related morbidity without compromising oncological outcomes. Three main OP strategies have been developed: Watch and Wait (W&W) strategy, Local Excision (LE) and Contact X-ray Brachytherapy (CXB), both applicable in patients showing a favourable tumour response after neoadjuvant therapy. The current challenge is defining the optimal timing and modalities for response assessment to accurately identify complete clinical response while balancing oncological control, functional outcomes and patient preferences. This trial evaluates whether a structured tumour response surveillance program combined with shared decision-making (SDM) can safely increase OP rates.

GRECCAR 20 is a multicentre, randomized, open-label, phase III trial enrolling patients with cT2-T3N0-1 rectal adenocarcinoma ≤ 8 cm from the anal verge and ≤ 4 cm in length, without involvement of the anal canal. Across the French GRECCAR and PRODIGE network, 270 patients will be recruited over 36 months. After neoadjuvant treatment (CRT or induction chemotherapy followed by CRT), participants are randomized to either a structured tumour response surveillance strategy with SDM over 8 to 24 weeks (experimental arm) or standard response assessment without SDM at 8 weeks (control arm). In the experimental arm (Arm A), reassessments at 2-, 4- and 6-month post-treatment will guide management decisions-W&W, LE, CXB or TME-through a collaborative process between patient and clinician. In the control arm (Arm B), treatment decisions at 2 months will be made solely by the clinician, between LE or TME, based on clinical, endoscopic and radiological assessment. The primary outcome is the OP rate at 2 years. Secondary endpoints include disease-free survival, TME-free survival, functional outcomes, quality of life (QoL) and patient-reported outcome measures (PROMs).

GRECCAR 20 is the first randomized trial to assess a structured tumour response surveillance program incorporating SDM in rectal cancer. By prioritizing patient values and QoL, this trial aims to improve OP rates without compromising oncological safety, potentially establishing a new standard of personalized, patient-centred care.