Quality-adjusted survival in a crossover trial of letrozole versus tamoxifen in postmenopausal women with advanced breast cancer.
BACKGROUND
Results from a phase III study of postmenopausal women with advanced breast cancer demonstrated longer time to disease progression for patients taking letrozole versus tamoxifen. This analysis compares the trade-offs between progression-free survival and toxicity.


METHODS
Quality-adjusted survival was calculated using Q-TWiST (quality-adjusted time without symptoms or toxicity). Survival curves were partitioned into three health states: toxicity (TOX), disease progression (PROG) and periods without toxicity or disease progression (TWiST). The utility-weighted sum of the health state durations was derived and compared.


RESULTS
There was not a significant difference in mean duration of serious adverse events prior to progression between the letrozole (n=453) and tamoxifen (n=454) groups (2.2 and 2 months, respectively). For TWiST, the mean duration for letrozole was 11.5 months, versus 8.5 months for tamoxifen (P <0.001). The mean duration of PROG was 11.5 months for letrozole and 12.7 months for tamoxifen (P=0.047). Using utility weights of 0.5 for TOX and PROG resulted in a 2.5-month difference in quality-adjusted survival favoring letrozole (P <0.0001).


CONCLUSIONS
The longer time to disease progression with letrozole versus tamoxifen was achieved without increased time with adverse events and resulted in more quality-adjusted survival for patients on letrozole.
Irish
W
W
Research Triangle Institute, Research Triangle Park, NC, USA. wirish@rti.org
Sherrill
B
B
Cole
B
B
Gard
C
C
Glendenning
G A
GA
Mouridsen
H
H
D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000188:drug therapy*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D000077289:Letrozole; D008875:Middle Aged; D009570:Nitriles / Q000627:therapeutic use*; D017698:Postmenopause; D011788:Quality of Life; D016019:Survival Analysis; D013629:Tamoxifen / Q000627:therapeutic use*; D014230:Triazoles / Q000627:therapeutic use*
D000970:Antineoplastic Agents; D009570:Nitriles; D014230:Triazoles; D013629:Tamoxifen; D000077289:Letrozole