Objective: To assess the antitumor activity and safety of aromatase inhibitors in advanced breast cancer.
Methods: Fifty-two advanced and female breast cancer patients with measurable and /or bone valuable tumor lesions were observed from June 2003 to September 2006. They were treated by aromatase inhibitors for at least 24 weeks, of whom 11 were treated less than 24 weeks because of disease progress; their age range was from 37 to 75 years (median 58); 8 patients were pre-menopausal, 6 with ovarian ablation and 2 with Goserelin to suppress ovarian function. Thirty-six patients were treated with exemestane, 13 with anastrozole and 3 with letrozole. Major items were observed including objective response rate (ORR=CR+PR), clinical benefit rate (CBR=CR+PR+SD>or=24 weeks), time to progress (TTP), time to failure (TTF), safety and toxicity.
Results: CR were 6 cases (11.5%) , with 1 case going on for 152 weeks, 1 case for 96 weeks, and other 4 cases for longer than 60 weeks; PR were 19 cases (36.5%), lasting 32-96 weeks; 16 cases obtained SD>or=24 weeks(30.8%); and 11 cases PD (progress of disease)+SD<24 weeks (21.2%). ORR were 48%, CBR 78.8%, and TTP 78.87 weeks (95% CI 61.13%-96.61%); although the patients who did not achieve objective response (group B) were treated with chemotherapy, radiotherapy or another kind of aromatase inhibitor, but their survival time was significantly different from that of the patients who achieved objective response (group A) when defined by Kaplan-Meier survival estimate. The over survival was 92% in group A, and 81.5% in group B when patients follow up more than 24 weeks [Log Rank (Mantel-Cox) analysis, chi2=3.85, P=0.047]; side effects were observed such as arthralgia, sweating, hot flash, and 2 patients developed heart failure with uncertain related drug before recovery.
Conclusion: The single agent effective rate of aromatase inhibitor was 48%. The patients had long term survival if they obtained CR or PR, and the side effects were well tolerated.