To estimate scenarios for survival for women with metastatic breast cancer (MBC) who are starting chemotherapy.
Patients and Methods
We sought randomized, first-line chemotherapy trials for MBC published from 1999 to 2009. We recorded median progression-free survival (PFS) and median overall survival (OS) and extracted the following percentiles (represented scenario) from each OS curve: 90th (worst-case), 75th (lower-typical), 25th (upper-typical), and 10th (best-case). We also estimated these scenarios for each OS curve by multiplying its median by four simple multiples: 0.25 (worst-case), 0.5 (lower-typical), 2 (upper-typical), and 3 (best-case). Estimates were deemed accurate if they were within 0.75 to 1.33 times the actual value.
From 36 trials (13,083 women), the mean for median PFS was 7.6 months (interquartile range [IQR], 6.0 to 9.0 months), the mean for median OS was 21.7 months (IQR,18.2 to 24.0 months), and the mean for the ratio of median OS to median PFS was 3.0 (IQR, 2.4 to 3.5). The mean for each OS scenario was worst-case, 6.3 months (IQR, 4.8 to 7.5 months); lower-typical, 11.9 months (IQR, 9.9 to 13.2 months); upper-typical, 36.2 months (IQR, 31.1 to 41.3 months); and best-case, 55.8 months (IQR, 47.5 to 60.2 months). Simple multiples of the median gave accurate estimates of the worst-case scenario in 73% of OS curves, lower-typical in 97%, upper-typical in 95%, and best-case in 96%. OS was longer in trials with higher proportions of estrogen receptor–positive tumors (P = .001) and in trials of trastuzumab-treated human epidermal growth factor receptor 2–positive tumors (P = .001).
Simple multiples of an OS curve's median can accurately estimate typical (half to double the median), best-case (triple the median), and worst-case (one quarter of the median) scenarios for survival."