NCRI Conference Abstracts
Clinical Trials Showcase

MRC OV05/EORTC 55955 Ovarian Cancer Trial of early treatment of relapse based on CA125 level alone versus delayed treatment

Gordon Rustin

Mount Vernon Cancer Centre, Northwood, UK

Background
 Serum CA125 often rises several months before women with ovarian cancer relapse. OV05/55955 investigated whether early treatment (ET) based on confirmed elevation of CA125 was beneficial compared to delayed treatment (DT) given when clinically indicated.

Method
 Women were registered if they were in complete remission from ovarian cancer having had first line platinum-based chemotherapy and with a normal CA125. CA125 was measured every 3 months and monitored by trials Units. Both patients and investigators were blinded. If CA125 exceeded twice the upper limit of normal, patients were randomised to ET or to continue with blinded CA125 tests only commencing treatment when clinical/symptomatic relapse was indicated (DT). All patients were treated as per local practice. The primary outcome measure was overall survival (OS). The study was designed to detect a 10% improvement in 2-year overall survival with ET with 85% power and 5% significance level (2-sided).

Results
Between 1996 and 2005 1442 patients were registered from 10 countries. A total of 529 patients were randomised (265 ET, 264 DT). Baseline characteristics were well balanced between randomised patients. Median age at registration was 61 years; 81% were FIGO stage III/IV. Second-line chemotherapy started a median of 4.8 months earlier in the ET arm. With a median follow-up of 57 months from randomisation, there was no evidence of a difference in OS between ET and DT arms, HR=1.00, 95%CI 0.82-1.22, p=0.98. Time to third-line treatment or death was 4.6 months earlier in the ET arm (12.5 months ET and 17.1 months DT; HR=0.69; p=0.0001). Quality of life was not improved by ET.

Conclusion
Patients with ovarian cancer should be told that there is no survival benefit from ET based on a raised serum marker level alone. Routine measurement of CA125 during follow-up should no longer be part of standard follow-up.