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NCT Number: NCT07200141

Simultaneous Boost in Neoadjuvant Radiotherapy for Rectal Cancer

The goal of this clinical trial is to learn whether new adjuvant radiotherapy with gross tumor volume(GTV) escalated to 58.75 Gy can improve complete response (CR) rates compared with GTV dose of 50 Gy in adult patients (18-79 years) with locally advanced rectal adenocarcinoma (T3-T4/N+, M0) located ≤10 cm from the anal verge.The main questions it aims to answer are:

1. Does GTV simultaneously boost to 58.75 Gy/25f increase complete response (pCR or cCR) compared with 50 Gy/25f? 2. How do the two regimens differ in terms of progression-free survival (PFS), pelvic local control (LC), tumor regression grade (TRG), organ preservation, and treatment-related toxicity? Researchers will compare GTV 58.75 Gy/25f (experimental arm) versus GTV 50 Gy/25f (control arm) to see if dose escalation improves tumor response rate.

Participants will:

1. Receive neoadjuvant radiotherapy with one of the two PGTV dose escalated regimens (with concurrent chemotherapy: oral capecitabine or XELOX). 2. Undergo restaging with imaging and clinical assessment before surgery or observation. 3. Proceed to total mesorectal excision (TME), local excision, or "watch-and-wait" strategy depending on treatment response and patient preference. 4. Be followed regularly with clinical exams, imaging, endoscopy, and laboratory tests to assess efficacy, safety, and long-term outcomes.

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Key information

Conditions

Locally Advanced Rectal Adenocarcinoma

Age range

18 year–80 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 2

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Age ≥18 and <80 years
  • Histologically confirmed rectal adenocarcinoma
  • Tumor located within 10 cm from the anal verge
  • MRI staging: T3-T4 and/or N+, M0 (AJCC 8th edition)
  • ECOG performance status 0-2
  • Adequate bone marrow function: WBC ≥3×10⁹/L, ANC ≥1.5×10⁹/L, PLT ≥100×10⁹/L, Hb ≥90 g/L
  • Adequate liver function: TBIL ≤1.5 × ULN, ALT/AST ≤2.5 × ULN
  • Adequate renal function: Cr ≤1.5 × ULN or CCr ≥60 mL/min
  • Signed informed consent

Exclusion criteria

  • Prior rectal cancer surgery
  • Prior induction chemotherapy, immunotherapy, or pelvic radiotherapy
  • History of other malignancies
  • History of chronic colitis, ulcerative colitis, or nonspecific proctitis
  • Pregnant or breastfeeding women
  • Active infection or fever
  • Severe uncontrolled comorbidities (e.g., unstable heart disease, renal disease, chronic hepatitis, uncontrolled diabetes, psychiatric disorders)
  • Inability to comply with study protocol

Treatment and study plan

GTV 58.75 Gy/25 fractions(Simultaneous Integrated Boost)

Radiation

Patients will receive neoadjuvant long course radiotherapy using VMAT or IMAT with daily image guided.

Gross tumor volume (GTV): A total dose of 58.75Gy delivered in 25 fractions using a simultaneous integrated boost approach; CTV: 45Gy/25f; Mesorectum lymph node(GTVnd1):58.75Gy/25f ; Lateral lymph node（GTVnd2）：60Gy/25f;

GTV 50 Gy/25 fractions(Simultaneous Integrated Boost)

Radiation

Patients will receive neoadjuvant radiotherapy with GTV 50 Gy in 25 fractions , delivered with IMRT or VMAT technique.

CTV: 45Gy/25f; Mesorectum lymph node(GTVnd1):58.75Gy/25f; Lateral lymph node（GTVnd2）

Concurrent chemotherapy

Drug

Concurrent administration of capecitabine (825 mg/m² twice daily, 5 days per week) or XELOX regimen during radiotherapy.

Total mesorectal excision (TME) surgery or non-operative management

Procedure

After treatment, patients will undergo restaging and proceed to total mesorectal excision (TME) or non-operative management ("watch-and-wait") depending on response and clinical assessment.

Primary outcomes

  1. CR

    Time frame: 1 year

    primary tumor achieved pathological complete response or clinical complete response.

Secondary outcomes

  1. 3-year disease free suvival rate

    Time frame: 3 years

    The proportion of patients from the initiation of surgery to tumor recurrence or death within 3 years

  2. 3-year local control rate

    Time frame: 3 years

    The proportion of patients absence of pelvic tumor progression, including primary tumor regrowth or regional lymph node progression, within 3 years after randomization.

  3. Tumor Regression Grade

    Time frame: 1 year

    Pathological tumor regression grade (TRG) according to CAP criteria.

  4. Number of participants with treatment-related adverse events as assessed by CTCAE v5.0

    Time frame: 3 years

    Acute and late adverse events will be graded according to Common Terminology Criteria for Adverse Events (CTCAE) version 5.0.

  5. Organ Preservation Rate

    Time frame: 1 year

    The proportion of patients who retain anal sphincter function without permanent stoma, including watch-and-wait, Dixon procedure or sphincter-preserving resection.

Sponsors and collaborators

Lead sponsor

Peking Union Medical College Hospital

Other

Registry information

Official study title

Simultaneous Boost in Neoadjuvant Radiotherapy for Rectal Cancer：A Phase 2, Randomized Controlled Study

Acronym: SIB-NCRT-pumch

Important dates

Study start
2025
Primary completion
2026
Study completion
2028
First posted
Sep 30, 2025
Registry last updated
Sep 30, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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