IMMUNOSCINTIGRAPHY IN COLORECTAL CANCER

摘要

Currently, radioimmunoscintigraphy (RIS) using radiolabelled monoclonal antibodies (MoAbs) directly against the carcinoembryonic antigen (CEA) has attracted wide interest for its value in the diagnosis and follow-up of patients with colorectal cancer. The purpose of the study was to determine the value of RIS with ~(99)Tc~m-labelled anti-CEA MoAb (BW 431/26) in patients with proven or suspected colorectal cancer. The study comprised 63 patients: 25 females and 38 males who are 57 ± 13 years old (mean ± SD). Fifty-seven patients were suspected to have recurrent colorectal adenocarcinoma with prior staging ranging from Duke's B1-C2, while another six patients were suspected of primary colorectal cancer. The patients received 1-2 mg of anti-CEA MoAbs labelled with 740-1000 MBq of ~(99)Tc~m. Images were obtained at 10 min, 4 and 24 h post-injection of the radioantibody. The efficacy of RIS in the detection of tumours was evaluated by histological confirmation and/or other diagnostic modalities and clinical follow-up. The overall sensitivity of RIS in the diagnosis of recurrent colorectal cancer was 83%, with a specificity of 89%. High sensitivity in the detection of locoregional recurrence and liver metastases was found in the study. RIS was more accurate than computed tomography (CT) scans in the detection of liver metastases and pelvic recurrence, while CT scans were far superior than RIS in detecting lung metastasis. Single photon emission computed tomography was clearly superior to planar imaging in detecting small lesions and locating them. RIS is most useful in patients who had rising CEA levels on clinical follow-up, but when other work-up was negative. The advantages of RIS include the ability to detect tumour recurrence prior to other investigation and in detecting tumour recurrence in areas such as the pelvis, where CT and magnetic resonance imaging are weakest in the diagnosis of recurrent disease.