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Adjuvant Radiation Therapy
Source: Colon Cancer Treatment (PDQ®)–Health Professional Version, National Cancer Institute.
Source updated: February 12, 2025 · Captured 2026-09-09.
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Context: Treatment Option Overview for Colon Cancer
While combined modality therapy with chemotherapy and radiation therapy has a significant role in the management of patients with rectal cancer (below the peritoneal reflection), the role of adjuvant radiation therapy for patients with colon cancer (above the peritoneal reflection) is not well defined. Patterns-of-care analyses and single-institution retrospective reviews suggest a role for radiation therapy in certain high-risk subsets of colon cancer patients (e.g., T4, tumor location in immobile sites, local perforation, obstruction, and residual disease postresection).[19-24]
Evidence (adjuvant radiation therapy):
A phase III, randomized, intergroup study evaluated the benefit of adding radiation therapy to surgery and chemotherapy with 5-FU-levamisole in selected patients with high-risk colon cancer (e.g., T4; or T3, N1–N2 ascending and/or descending colon).[25]
Source links and citations
A phase III, randomized, intergroup study evaluated the benefit of adding radiation therapy to surgery and chemotherapy with 5-FU-levamisole in selected patients with high-risk colon cancer (e.g., T4; or T3, N1–N2 ascending and/or descending colon).[25]
This clinical trial closed early secondary to inadequate patient accrual. An analysis of 222 enrolled patients (the original goal was 700 patients) demonstrated no relapse or OS benefit for the group that received radiation therapy, although the sample size and statistical power were inadequate to exclude benefit.
Adjuvant radiation therapy has no current standard role in the management of patients with colon cancer following curative resection, although it may have a role for patients with residual disease.
Publication references
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Preserved source evidence · Not medical advice