Superiority of SPET to planar imaging in the detection of colorectal carcinomas with 111In monoclonal antibodies

Monoclonal immunoscintigraphy for detection of metastasis and recurrence of colorectal cancer

AIM: To assess the clinical role of monoclonal immunoscintigraphy for the detection of metastasis and recurrence of colorectal cancer.

METHODS: Monoclonal immunoscintigraphy was performed in patients operated on for colorectal adenocarcinoma suspected of local recurrence and metastatic disease. The results were compared with conventional diagnostics.

RESULTS: Immunoscintigraphic investigation was done in 53 patients. Tumor recurrence occurred in 38 patients, and was confirmed by other diagnostic modalities in 35. In 15 patients, immunoscintigraphic findings were negative, and confirmed in 14 with other diagnostic methods. Comparative analysis confirmed good correlation of immunoscintigraphic findings and the results of conventional diagnostics and the level of tumor marker carcinoembryonic antigen. Statistical analysis of parameters of radiopharmaceutical groups imacis, indimacis and oncoscint presented homogenous characteristics all of three radiopharmaceuticals. The analysis of immunoscintigraphic target focus was clearly improved using tomography.

CONCLUSION: Immunoscintigraphy is highly specific and has a good predictive value in local recurrence of colorectal cancer.

[Indium 111-labeled antibodies in the detection of colorectal carcinoma]

The aim of the study is detection of the recurrences and metastases of colorectal carcinomas using (111)In labelled antibodies B72.3 in 14 patients. With tomography, we can access better distinction of tumour in comparison to other structures and estimation of its size. Other imaging methods (CT, US) have advantage in detection of liver metastases, while immunoscintigraphy is more specific for the assessment of malignant abdominal tumours and extrahepatic metastases. The first results point out that Oncoscint CR-103 can be useful in diagnosis of recurrences and metastases of colorectal carcinoma, viability assessment after radiotherapy and in the choice of the adequate surgical treatment in dependence of the spread of the disease.

Antibody imaging in breast cancer

Radiolabeled antibodies have been studied by several investigators for their ability to detect and stage breast cancers. Studies with Technetium-99m labeled anti-CEA monoclonal antibodies, Iodine-123, Indium111 labeled anti-mucin antibodies such as HFMG, B72.3, anti-TF and Iodine-125 labeled B72-3 have demonstrated the ability of radioimmunoscintigraphy in detecting over 80% of breast cancer lesions, but lower sensitivity and specificity for accurate staging of the axillae. Non-specific localization of radiolabeled monoclonal antibodies in tumor negative nodes even following lymphoscintigraphy appear to be the major factor limiting the widespread clinical application of radioimmunoscintigraphy in staging newly diagnosed breast cancer patients. Preliminary studies with Tc-99m labeled CEA-Scan appear to indicate a useful role of this agent in distinguishing between benign and malignant breast lesions in patients with indeterminate mammographic findings.