ANTI-CEA IMMUNOSCINTIGRAPHY AND COMPUTED TOMOGRAPHIC SCANNING IN THE PREOPERATIVE EVALUATION OF MEDIASTINAL LYMPH-NODES IN LUNG-CANCER

Background - Thoracic computed tomography (CT) provides most of the st aging information needed before operation for lung cancer and can redu ce the number of exploratory thoracotomies. In recent years a new immu noscintigraphic technique with anti-carcinco embryonic antigen (CEA) m onoclonal antibodies has been shown to be effective in lung cancer sta ging. This study compares the yields of CT scans and immunoscintigraph y in the preoperative evaluation of the mediastinal lymph nodes of pat ients with non-small cell lung cancer. Methods - One hundred and thirt y one patients believed on clinical grounds to have an operable non-sm all cell lung cancer were photoscanned with the indium-111 labelled F( ab')2 fragments of the antibody FO23C5. Both planar and single photoem ission computed tomography (SPECT) thoracic views were recorded. CT sc ans of the thorax, abdomen, and brain were obtained in all patients. S eventy of the patients eventually underwent surgery, an additional sev en underwent mediastinoscopy or mediastinotomy, and a further 10 had b oth cervical exploration and thoracotomy. Pathological evaluation of t he mediastinal nodes was available in all 87 patients, but in only 80 of them was the diagnosis of lung cancer eventually confirmed. Results - The diagnostic accuracy of planar immunoscintigraphy, SPECT immunos cintigraphy, and CT scanning for N2 disease was 76%, 74%, and 71%, res pectively. The corresponding sensitivity and specificity rates were 45 %, 77%, 64% and 88%, 72%, and 74%. These were not significantly differ ent. Conclusions - This study shows that anti-CEA immunoscintigraphy h as no advantage over conventional CT scanning in assessing mediastinal lymphoadenopathy in patients with lung cancer. CT scanning remains th e gold standard test in these patients.