Predicting Response of Ovarian Cancer to Paclitaxel Treatment Based on Trend Analysis of Serum CA125

Abstract

Recent randomized studies have reported significantly improved quality of life and survival in cancer patients who underwent tumor marker-directed treatment compared with patients treated according to Union Internationale Contre le Cancer (UICC) criteria [see Ref. (1) and references therein]. According to these studies, systematic analysis of tumor markers may document whether therapy is effective and should be continued in spite of its ultimate adverse toxic effects or whether it should be terminated because of ineffectiveness. The advantages of biochemical assessment are objectivity and reproducibility as well as the fact that tumor marker assays are subjected to longitudinal external and internal quality control. We aimed to determine whether changes in serum concentrations of the tumor marker CA125 evaluated by a newly developed algorithm predict response to chemotherapy in paclitaxel-treated ovarian cancer patients. Ovarian cancer patients with advanced disease (stage III at the time of diagnosis; n = 101; median age, 56 years; age range, 33–69 years) were enrolled in a prospective study monitoring changes in serum CA125 and the effect of therapy. Patients were treated with paclitaxel (Taxol; Bristol-Myers-Squibb) as part of a first-line combination chemotherapy. They received a median of six courses (range, three to nine) of chemotherapy. During a total of 689 chemotherapy cycles, serum CA125 concentrations were evaluated (AxSYM; Abbott Laboratories) and externally controlled through the CAPTMX tumor marker survey. Serum samples were obtained before starting therapy (specimen c ) and before each chemotherapy cycle (specimens c 1– c n). The univariate Cox regression model and the stepwise Cox regression model were used for selecting the optimal variables that most accurately predicted disease-free interval. The statistical package SAS, release 8.22 (SAS, Inc.), was used. The time-to-progression (TTP) in different patient groups was compared using Wilcoxon and log-rank tests. CA125 concentrations between groups of responders and nonresponders to …