Immunoscintigraphy of colorectal carcinomas with radiolabeled monoclonal antibody fragments.

Background/aims: The aim was evaluation of the accuracy and clinical impact of the immunoscintigraphy for the detection of metastases and recurrences of colorectal carcinomas using two different radiolabeled antibody fragments.

Methodology: The study was performed in 5 patients with IMACIS 1 containing the cocktail of 111MBq 131I MoAb 19-9 F(ab')2 and MoAb anti-CEA F(ab')2 and 8 patients with INDIMACIS 19-9 containing 150MBq of 111In-labeled MoAb 19-9 F(ab')2.

Results: With IMACIS 1, in all the patients, both tumor marker values were elevated. The number of TN was 3/5 and TP 2/5. From 2 TP, one had recurrence of the diseases with peritoneal carcinosis and one with liver metastases. In one patient, the results influenced the therapeutical management. With INDIMACIS 19-9, there were 2/8 TN, with borderline value of CEA and CA 19-9. TP were 6/8 (all with elevated tumor marker values, five of them many times; 3 with recurrences, 1 with recurrence and liver metastases and two with only liver metastases. In three patients, immunoscintigraphy influenced patient management.

Conclusions: With both radiopharmaceuticals, immunoscintigraphy significantly influenced the patient management or it was complementary. It would be performed in the detection of recurrence, assessment of viability and follow-up of the therapy.