The role of radioimmunoscintigraphy and computed tomography scan prior to reassessment laparotomy of patients with ovarian carcinoma. A preliminary report.

BACKGROUND

Accurate evaluation of patients with ovarian carcinoma who have completed primary therapy often requires surgical exploration. Radioimmunoscintigraphy (RIS) represents an evolving technique that may allow noninvasive detection and localization of persistent or recurrent disease in these patients.

METHODS

Our prospective, blinded study enrolled patients with normal CA 125 levels and no clinical evidence of disease after primary cytoreductive surgery and cytotoxic chemotherapy for ovarian carcinoma. Each patient underwent RIS using Indium-satumomab pendetide (labeled antibody B72.3 to the tumor-associated antigen TAG-72) and abdominal/pelvic computed tomography (CT) prior to reassessment laparotomy.

RESULTS

Twenty patients were enrolled from January 1994 to January 1995. Two patients with negative RIS scans refused reassessment laparotomy and were without evidence of disease > 15 months from the study. Twelve of the remaining 18 patients (66.7%) had histologically proven disease at reassessment laparotomy. RIS images indicated the presence of disease in all 12 patients, whereas CT scans detected disease in only 2 patients. In three of five patients, biopsy-proven microscopic disease (no gross disease at the time of laparotomy) was found only in specimens obtained by RIS-directed biopsies. RIS was superior to CT in sensitivity (100% vs. 16.7%), accuracy (72% vs. 33%), and negative predictive value (100% vs. 28.6%) (P < 0.005).

CONCLUSIONS

Routine use of CT is of limited value in the assessment of ovarian carcinoma patients with negative physical examinations and normal CA 125 levels. With its high level of sensitivity and negative predictive value, RIS may play a role in the detection of persistent disease in this population and aid in the classification of patients into three distinct groups: those with gross residual disease, small volume or microscopic disease, and no disease. Separation of this heterogenous group without surgery may help guide subsequent consolidation therapy. However, attaining a high level accuracy with RIS, depends on optimizing the method of image acquisition, the timing of scans, and the reconstruction of data.