Immunoscintigraphy with 131I-labelled monoclonal antibodies HMFG2 and HMFG1 F(ab')2 versus abdominal CT scan in the detection of residual disease in ovarian cancer patients.

131I-labelled HMFG2 or HMFG1 F(ab')2 monoclonal antibody (MAb) was administered intraperitoneally to 15 patients with epithelial ovarian cancer who had completed chemotherapy and were in complete or good partial remission. Each patient received 2-3 mCi. Patients were scanned immediately after and until 7 days post-injection. In 3/15 patients the immunoscan failed because extensive adhesions from the previous surgery prevented MAb diffusion. Of the remaining 12 patients, 9 underwent second-look laparotomy (SL). Immunoscan was true positive in 8/9 (89%) patients and equivocal in 1/9 (11%), whereas the abdominal CT scan gave true positive results in 6/9 (67%) patients. In 8 out of 9 patients there was a good correlation between distribution of all sites of abnormal uptake and the surgical findings at SL. Of the 3 patients not undergoing SL, the immunoscan was positive in all, whereas clinical examination and abdominal CT scan were negative. All 3 patients relapsed after 3, 4 and 5 months. Thus the total true positivity of immunoscan reached 92%, CT scan remaining at 50%. Immunoscan with intraperitoneal administration of 131I-labelled MAbs can thus accurately detect the presence of residual disease in ovarian cancer patients and appears more sensitive than abdominal CT scan.