Immunoscintigraphy using 111in-labelled F(ab')2 fragments of anti-carcinoembryonic antigen (CEA) monoclonal antibody for staging of non-small cell lung carcinoma

Radiologic evaluation in lung cancer: diagnosis and staging

Radiology and surgery are not competing but are complementary modalities in the care of patients with lung cancer. In certain areas, such as evaluation of the solitary pulmonary nodule, radiologic studies can have an important impact on patient care. Mediastinal staging with imaging studies is inexact, and CT may be most effective as a road map for more definitive surgical staging. MRI currently offers no advantages over CT in staging of the mediastinum but can be helpful in evaluation of parts of the chest not well demonstrated on axial images. A discussion of newer nuclear medicine imaging modalities is included.

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 staging information needed before operation for lung cancer and can reduce the number of exploratory thoracotomies. In recent years a new immunoscintigraphic technique with anti-carcinoembryonic antigen (CEA) monoclonal antibodies has been shown to be effective in lung cancer staging. This study compares the yields of CT scans and immunoscintigraphy in the preoperative evaluation of the medistinal lymph nodes of patients with non-small cell lung cancer.

METHODS

One hundred and thirty one patients believed on clinical grounds to have a operable non-small cell lung cancer were photoscanned with the indium-111 labelled F(ab')2 fragments of the antibody FO23C5. Both planar and single photoemission computed tomography (SPECT) thoracic views were recorded. CT scan of the thorax, abdomen, and brain were obtained in all patients. Seventy of the patients eventually underwent surgery, an additional seven underwent mediastinoscopy or mediastinotomy, and a further 10 had both cervical exploration and thoracotomy. Pathological evaluation of the 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 immunoscintigraphy, and CT scanning for N2 disease was 76%, 74%, and 71%, respectively. The corresponding sensitivity and specificity rates were 45%, 77%, 64% and 88%, 72%, and 74%. These were not significantly different.

CONCLUSIONS

This study shows that anti-CEA immunoscintigraphy has no advantage over conventional CT scanning in assessing mediastinal lymphoadenopathy in patients with lung cancer. CT scanning remains the gold standard test in these patients.

[Immunoscintigraphy in oncology]

In vivo immunotargeting of specific antigens with radiolabeled monoclonal antibodies is a new method of diagnosis which has largely improved over the past 15 years. It has been especially developed in the oncologic field. Although it is not yet a daily procedure, immunoscintigraphy has been proven a useful diagnostic tool in many situations. It gives information about the presence of lesions and their neoplastic nature. For this reason, immunoscintigraphy appears as very complementary to morphological imaging and is mainly indicated when lesions have insufficient anatomical definition. Early detection of recurrences is actually the best indication of immunoscintigraphy. However, some problems still exist, concerning the tumor/tissues uptake ratio which is not sufficient for an optimal imaging contrast, and the apparition of human anti-mouse antibodies (HAMA) in the patients. At present, many works are in progress which could resolve these problems. Ultimately, well-performed clinical trials are necessary to establish the right place for immunoscintigraphy in the diagnostic and therapeutic strategies in oncology.