Long-term follow-up of women enrolled in a randomized trial of adjuvant chemotherapy for early stage ovarian cancer (ICON1)

Abstract

5509 Background: ICON1 and a meta-analysis of all relevant trials demonstrated an improvement in 5 year recurrence-free and overall survival (RFS and OS) for women with early-stage epithelial ovarian cancer (ES EOC) treated with adjuvant chemotherapy compared to no adjuvant chemotherapy. We aimed to determine if this initial benefit is maintained long-term and whether benefit is different with different risk groups of patients defined by stage, grade and histology. Method: 477 women with ES EOC were recruited from centres in Italy (271 women) UK (195) Switzerland (11) between August 1991 and January 2000. 5-year results were presented at ASCO 2001. Systematic long-term follow up was planned and completed in May 2006. Results: With a median follow-up of 9.2 years, 168 women have developed recurrent disease or died and 144 women have died. The Hazard Ratio (HR) for RFS of 0.70 in favour of adjuvant chemotherapy (95% CI 0.52–0.95 p= 0.023) translated into an improvement of 10-year absolute RFS of 10% from 57 to 67%. For OS, HR was 0.74 (95% CI 0.53–1.02 p= 0.066), a corresponding improvement in 10-year absolute OS of 8% from 64% to 72%. 26% of patients died from causes other than ovarian cancer. Stage I patients were grouped as low (Ia, grade 1), medium (Ia grade 2, Ib or Ic grade 1) and high risk (Ia, grade 3, Ib or IC grade 2 or 3, any clear cell). The test of interaction between risk groups and adjuvant treatment for RFS and OS was 0.055 and 0.13, respectively. The HR, 95%CI and p value are summarised in the table . Conclusions The long-term benefit of adjuvant treatment on RFS is confirmed. There is clear evidence that adjuvant chemotherapy reduces the risk of recurrence/death or death alone in high-risk patients but not in the low-risk group. [Table: see text] [Table: see text]