NCT06246344

Adaptive Boost Radiotherapy to Primary Lesions and Positive Nodes in the Neoadjuvant Treatment of Locally Advanced Rectal Cancer

Efficacy and Safety of Adaptive Boost Radiotherapy to Primary Lesions and Positive Nodes in the Neoadjuvant Treatment of Locally Advanced Rectal Cancer: A Prospective, Randomized, Controlled, Phase III Trial

• Status: Recruiting
• Phase: —
• Study type: Observational
• Enrollment: 128 (estimated)
• Sponsor: Shandong Cancer Hospital and Institute · Academic / Other
• Sex: All
• Age: 18 Years – 75 Years
• Healthy volunteers: Not accepted

Summary

This is a multicenter, randomized, controlled phase III trial to evaluate the efficacy and safety of adaptive boost radiotherapy to the primary lesions and positive lymph nodes based on MR or CBCT or FBCT-guided adaptive radiotherapy in the neoadjuvant treatment of locally advanced rectal cancer.

Detailed description

Locally advanced rectal cancer (LARC), typically stage II (cT3-4/N0) or stage III (cT1-4/N1-3), requires multimodal treatment. Surgical resection alone is associated with a high rate of local recurrence. Neoadjuvant chemoradiotherapy (nCRT) followed by total mesorectal excision (TME), on the other hand, can better control local recurrence in LARC patients. However, the overall pathological complete response (pCR) rate and clinical complete response (cCR) rate are still low, and there is an inconsistency between them, Therefore, the preservation of the anus is still a challenge. Optimizing neoadjuvant treatment strategies, including strategies such as increasing concurrent chemotherapy and increasing the dose of radiotherapy, is essential to improve tumor regression and anal preservation. Radiotherapy is an important treatment for controlling local recurrence and downstaging LARC. A common cause of cancer recurrence in rectal cancer is that tumor cells metastasise nearby positive lymph nodes, such as the lateral pelvic lymph nodes These sites can serve as refuges where the cancer can regroup and either recur at the original site or spread to other areas. Various studies have also investigated the role of radiotherapy dose escalation in promoting tumor regression. Seldom have these studies examined dose escalation to both the primary lesions and positive lymph nodes. One of the major limiting factors is the tradeoff between destruction of the cancer itself and collateral damage to the neighboring healthy tissues. However, recent advances in the field have made great strides in overcoming this obstacle. Adaptive radiation therapy (ART), including magnetic resonance (MR)-guided, cone beam computed tomography (CBCT)-guided, and fan beam computed tomography (FBCT)-guided, allows direct imaging of the target and organs at risk (OAR), combined with optimization of the treatment plan for anatomical changes, to deliver high-quality dose escalation regimens to improve treatment response while protecting OAR such as the bladder, femoral heads, and small bowel. We hypothesize that by implementing simultaneous integrated boost (SIB) or sequential boost (SB) radiotherapy to both the primary lesions and positive lymph nodes based on ART, we can improve the cCR and pCR rates without increasing surgical difficulty, while maintaining tolerable safety. Against the above background, this study aims to conduct a multicenter, randomized, controlled phase III trial to evaluate the efficacy and safety of SIB or SB radiotherapy to the primary lesions and positive lymph nodes based on MR or CBCT or FBCT-guided ART in the neoadjuvant treatment of LARC. Eligible patients will be randomized 1:1 into experimental and control groups, both of which will undergo long course concurrent chemoradiotherapy (LCCRT), consolidation chemotherapy and TME surgery. During LCCRT, the experimental group will receive SIB or SB dose escalation based on MR or CBCT or FBCT-guided ART, while the control group will receive conventional dose without ART.

Conditions

• Rectal Cancer

Interventions

Type	Name	Description
RADIATION	Adaptive Boost Radiotherapy	The choice of adaptive protocol and delivery system is based on individual tumor characteristics, patient anatomy and institutional capabilities. This approach provides flexibility in treatment planning while adhering to evidence-based dose constraints. Adaptive radiotherapy is delivered using one of the following advanced platforms: the Elekta Unity MRI Linac (MR-guided) or Varian Ethos (CBCT-guided), or the United Imaging uRT-linac 506c (FBCT-guided). ART Option 1 (simultaneous integrated boost, SIB): GTVp+GTVn: A total dose of 60-65 Gy delivered in 25 fractions using a simultaneous integrated boost approach. CTV: A total dose of 45-50 Gy delivered in 25 fractions. ART Option 2 (sequential boost, SB) GTVp+GTVn: An initial hypofractionated boost with a total dose of either 9-12 Gy delivered in 3 fractions or 10 Gy delivered in 2 fractions. CTV: Followed by standard fractionation delivering 45-50 Gy in 25 fractions.
RADIATION	Long course non-ART radiotherapy	Conventional long-course radiotherapy administered in a non-adaptive manner without dose escalation. Treatment will be targeted to the pelvic lymphatic drainage region only. A total dose of 45-50 Gy will be delivered in 25 fractions over the course of treatment.
DRUG	Concurrent chemotherapy	Capecitabine (825 mg/m2, po, twice daily)
DRUG	Consolidation Chemotherapy	Following the completion of concurrent chemoradiotherapy, consolidation chemotherapy will commence 7 to 10 days later. Patients will receive two cycles of the CAPEOX regimen. Each cycle comprises: Capecitabine: 1.0 g/m² administered orally twice daily on days 1 through 14, and Oxaliplatin: 130 mg/m² administered intravenously on day 1.
PROCEDURE	Total mesorectal excision (TME) surgery	Total mesorectal excision surgery

Timeline

• Start date: 2023-12-01
• Primary completion: 2025-12-01
• Completion: 2028-12-01
• First posted: 2024-02-07
• Last updated: 2025-03-12

Locations

1 site across 1 country: China