Does the progression-free interval after primary chemotherapy predict survival after salvage chemotherapy in advanced and recurrent endometrial cancer?: a Gynecologic Oncology Group ancillary data analysis.

ABSTRACT

BACKGROUND: This study evaluated whether progression-free interval (PFI) following primary chemotherapy (PCT) was predictive of overall survival (OS) after second-line chemotherapy in advanced/recurrent endometrial cancer (EC). METHODS: This is a pooled analysis of patients who recurred after PCT and were treated with second-line chemotherapy on Gynecologic Oncology Group trials. PFI-1 measured from initiation of PCT to recurrence or treatment-free interval (TFI) measured from completion of PCT to initiation of second-line chemotherapy was evaluated in relation to clinical outcomes. RESULTS: A total of 586 patients treated on 5 phase 3 PCT protocols were included. Baseline factors in primary setting associated with clinical outcome after PCT were also predictive of OS after second-line chemotherapy, including race, Gynecologic Oncology Group performance status, grade, and prior radiation therapy (P<.01). PFI-1 was the most significant factor predictive of survival after second-line chemotherapy, with a 30% reduction in the risk of death for PFI-1>6 months compared with ≤6 months (hazard ratio [HR], 0.70; 95% confidence interval [CI], 0.59-0.84 [P<.0001]) and median OS after second-line chemotherapy of 10 versus 5 months. A total of 275 patients treated on 9 phase 2 second-line chemotherapy protocols were also evaluated, and TFI>3 months was associated with a 25% reduction in the risk of death (HR, 0.75; 95% CI, 0.57-0.97 [P=.030]) and median OS after second-line chemotherapy of 10 versus 7 months compared with TFI≤3 months. The tumor response to second-line chemotherapy was 9.6% versus 5.8%; the difference was not statistically significant. CONCLUSIONS: Time to recurrence after PCT is predictive of survival after recurrence in advanced/recurrent EC. However, there is no evidence that this variable can be used in selecting salvage chemotherapy.