Radioimmunotherapy after chemotherapy compared to chemotherapy alone in the treatment of advanced ovarian cancer: a matched analysis.

Ovarian cancer has an overall five-year survival of around 30% in spite of complete remissions being obtained after optimal surgery and platinum-based chemotherapy. Previous studies have indicated a survival advantage for patients treated with radiolabelled monoclonal antibodies (radioimmunotherapy). We report here on the survival of patients who received single-dose intraperitoneal radioimmunotherapy after having achieved complete remission with standard management. Twenty-five patients with epithelial ovarian cancer, stages Ic-IV, received adjuvant intraperitoneal radioimmunotherapy following completion of conventional chemotherapy. On achieving complete remission they receive once 25 mg of HMFG1 labelled with 18 mCi/m2. Controls for cases were sought from the database of the North Thames ovary group (NTOG). Controls were selected on the basis of stage, histological grade and type, and age of patient at diagnosis. Kaplan-Meier survival plots were constructed for cases and controls and subjected to statistical analysis with the log-rank test. Additionally, using a database of 84 NTOG patients known to be disease-free at the end of chemotherapy, estimated survival curves were constructed using Cox's proportional hazards regression model. Close matches were found for 20 of the 25 patients. Median survival has not been reached at a median follow-up of 59 months for cases and 27 months for controls. Survival at five years is 80% for cases and 55% for controls (p=0.0035). The Cox model estimates long-term (10-year) survival of 70% for patients who received radioimmunotherapy, compared to 32% for those that did not (p=0.003). All patients developed serological evidence of human anti-mouse antibody (HAMA). This study shows a likely survival benefit for patients with ovarian cancer who receive intraperitoneal radioimmuno-therapy in the adjuvant setting.