Purpose: The Japan Clinical Oncology Group (JCOG) trial JCOG0505 demonstrated the statistically significant non-inferiority of paclitaxel plus carboplatin (TC) to paclitaxel plus cisplatin (TP) in terms of overall survival (OS) in metastatic or recurrent cervical cancer. In that trial, patients were randomly assigned, adjusting for institution and known prognostic factors. The objective of this ancillary study was to evaluate the appropriateness of the adjustment factors used to have randomly assigned treatments and to investigate new potentially useful prognostic factors of paclitaxel plus platinum for future randomized trials in metastatic or recurrent cervical cancer.
Methods: The study subjects comprised 244 eligible patients in the JCOG0505 who were merged to have received either TC or TP. The effects of the following factors on OS were investigated using a Cox regression model taking into consideration the adjustment factors used in randomization in this trial (e.g., performance status [PS]) and other baseline factors, including platinum-free interval (PFI), pretreatment hemoglobin levels (PHLs), and pretreatment platelet counts (PPCs).
Results: The median follow-up was 17.6 months, and median OS was 18.0 months. The hazard ratio was 1.83 in patients with a PS of 1 or 2 (vs. 0; P = 0.0004; 95 % confidence interval [CI] 1.31-2.55), 2.92 in patients with a PFI of <6 months (vs. PFI of ≥12 months; P < 0.0001; 95 % CI 1.73-4.91), 2.09 in patients with a PFI of <12 months (vs. PFI of ≥12 months; P = 0.0034; 95 % CI 1.28-3.44), and 0.69 in patients with PHL higher than or equal to the median value (vs. less than the median; P = 0.016; 95 % CI 0.51-0.93). No significant differences were obtained for PPC or the other known factors.
Conclusions: In addition to the known prognostic factor of PS, which was used as an adjusting factor, a PFI of <12 months and lower PHL were newly demonstrated to be associated with poor outcomes in patients with metastatic or recurrent cervical cancer. These new prognostic factors should be validated in future prospective trials.
Clinical trial information: UMIN-CTR[ http://www.umin.ac.jp/ctr/ ] ID: C000000335.
Keywords: Cervical cancer; Metastatic; Platinum-free interval; Pretreatment hemoglobin level; Recurrent.