AbstractBackgroundDespite the success of radioimmunotherapy (RIT) using radiolabelled monoclonal antibodies (Mabs) directed against tumour-associated antigens in the treatment of non-Hodgkin's lymphoma, therapeutic success in solid tumours has been modest. In the past decade, a dozen Mabs have been investigated clinically for their potential usefulness in RIT of colorectal cancer.MethodsThe application of radiolabelled Mabs for the treatment of solid cancers is discussed, and clinical trials investigating RIT for colorectal cancer listed in the Medline and Embase databases are reviewed.ResultsUptake of radiolabelled Mabs in tumour and, consequently, the therapeutic efficacy of RIT is inversely correlated with tumour size. The bone marrow is the most important dose-limiting organ. Twenty-three phase I/II studies were found that investigated the feasibility and efficacy of RIT using five radionuclides and 15 Mabs against carcinoembryonic antigen, tumour-associated glycoprotein 72, epithelial cellular adhesion molecule, A33 or colon-specific antigen p, mainly in patients with advanced colorectal cancer. A few responses were recorded but no particular antibody construct seemed superior.ConclusionRIT might be an effective adjuvant treatment modality in colorectal cancer. Future studies should focus on its application in patients with small-volume or minimal residual disease.