Preoperative Radiotherapy with a Simultaneous Integrated Boost Compared to Chemoradiotherapy for cT3-4 Rectal Cancer:...

Area of Science:

• Oncology
• Radiation Oncology
• Gastrointestinal Oncology

Background:

• Preoperative chemoradiotherapy (CRT) is the standard treatment for locally advanced rectal cancer (T3-4).
• Novel treatment strategies are being explored to improve outcomes and patient tolerance.
• This study compares standard CRT with a novel image-guided intensity-modulated RT (IG-IMRT) and simultaneous integrated boost (SIB) approach.

Purpose of the Study:

• To compare the efficacy and safety of preoperative IG-IMRT with SIB (RTSIB) versus standard CRT in patients with T3-4 rectal cancer.
• To evaluate metabolic response, toxicity, overall survival (OS), progression-free survival (PFS), and local control (LC).

Main Methods:

• A multi-center randomized trial involving 174 patients with cT3-4 rectal cancer.
• Patients were assigned to either preoperative CRT (IG-IMRT + capecitabine) or RTSIB (IG-IMRT with SIB to the tumor up to 55.2 Gy).
• Outcomes including toxicity, metabolic response (SUVmax change), pCR, OS, PFS, and LC were assessed.

Main Results:

• Grade 3 acute toxicities were comparable (6% in CRT vs. 4% in RTSIB).
• No significant difference in metabolic response (SUVmax change) between arms (p=0.43).
• Pathologic complete response (pCR) was 24% with CRT versus 14% with RTSIB; however, 5-year OS, PFS, and LC showed no significant differences.

Conclusions:

• The preoperative RTSIB approach is non-inferior to standard CRT regarding metabolic response, toxicity, OS, PFS, and LC.
• RTSIB offers a valuable alternative treatment option for rectal cancer patients who are not candidates for fluorouracil-based CRT.