Oxaliplatin addition to rectal cancer chemoradiation improves tumor regression

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International journal of radiation oncology, biology, physics Published June 2, 2026 Medically reviewed June 2, 2026 Study authors: Zhou Jiaolin, Li Ganbin, Jia Wenzhuo, Xiao Yi, Wu Aiwen, Wu Bin, Wang Zhenjun, Liu Qian, Yao Hongwei… PubMed ↗ DOI ↗ By Dr. Amelia Tan, PhD · Internal Medicine & Chronic Disease

Key Takeaway

Adding oxaliplatin to chemoradiation improves tumor regression in high-risk rectal cancer but does not boost survival.

A multicenter randomized trial evaluated the addition of oxaliplatin to standard capecitabine-based chemoradiation for patients with high-risk locally advanced rectal cancer. The study compared long-course radiation with either a three-cycle regimen of capecitabine and oxaliplatin or capecitabine alone. The primary goal was to assess 3-year disease-free survival, with secondary outcomes including surgical and pathologic responses.

Results showed no significant difference between the CapeOX and Cape groups in radical surgery rates or pathologic complete response rates. However, the CapeOX group demonstrated a significantly higher rate of marked tumor regression, with 58.6% achieving CAP 0-1 versus 46.8% in the Cape group. Grade 3-4 treatment-related toxicities were numerically higher with oxaliplatin but not statistically significant.

At a median follow-up of 37 months, 3-year disease-free and overall survival were comparable between groups. Notably, patients with better tumor regression (CAP 0-1) had significantly improved 3-year disease-free survival. The addition of oxaliplatin enhanced pathologic response without a major safety penalty, but this did not translate into a long-term survival benefit.

Study Details

Study typeRct

Sample sizen = 248

EvidenceLevel 2

Follow-up36.0 mo

PublishedJun 2026

PMID41352689

View Original Abstract ↓

PURPOSE: The clinical benefit of incorporating oxaliplatin into conventional neoadjuvant chemoradiotherapy (nCRT) for patients with high-risk locally advanced rectal cancer (LARC) remains controversial. METHODS AND MATERIALS: This multicenter, open-label, randomized controlled trial enrolled 505 patients with high-risk LARC, defined by the presence of at least 1 of the following adverse features: clinical T4 stage, clinical N2 stage, high tumor grade, extramural vascular invasion, involvement of the mesorectal fascia, or perianal musculature involvement. Enrollment took place between August 2017 and April 2022. Patients were randomly assigned to receive long-course radiation therapy combined with a 3-cycle chemotherapy regimen of capecitabine and oxaliplatin (CapeOX group; n = 248) or capecitabine alone (Cape group; n = 257). The primary endpoint was 3-year disease-free survival (3y-DFS). RESULTS: Following nCRT, radical surgery was performed in 91.5% of the CapeOX group and 92.2% in the Cape group (P = .778). Pathologic complete response rates were comparable between the CapeOX and Cape groups (25.5% vs 25.3%; P = .954). A significantly greater proportion of patients in the CapeOX group achieved marked tumor regression (College of American Pathologists (CAP 0-1)) compared with the Cape group (58.6% vs 46.8%; P = .011). The incidence of grade 3 to 4 treatment-related toxicities was similar between the groups (CapeOX: 14.1% vs Cape: 9.3%; P = .095). After a median follow-up of 37 months, 3y-DFS and 3-year overall survival rates were comparable between the groups (both P > .050). Overall, patients who achieved CAP 0 to 1 had significantly better 3y-DFS than those with CAP 2 to 3 (89.0% vs 80.9%; P = .018). CONCLUSIONS: The addition of oxaliplatin to conventional nCRT may enhance pathologic tumor regression in patients with high-risk LARC without a significant increase in severe adverse events. However, this intensified 3-cycle chemotherapy regimen did not translate into a long-term survival benefit.