Diffusion of aromatase inhibitors for breast cancer therapy between 1996 and 2003 in the Cancer Research Network.
OBJECTIVE
Clinical trials demonstrated adjuvant aromatase inhibitor treatment is superior for decreasing breast cancer recurrence risk over adjuvant tamoxifen treatment as early as 2001. Yet clinical use for adjuvant treatment was not recommended by the American Society of Clinical Oncology until 2004. Aromatase inhibitor uptake after the first public presentation of randomized trial results but before the release of national guidelines is unclear. We evaluated diffusion of aromatase inhibitor dispensings for breast cancer treatment in integrated healthcare delivery systems across the United States.


METHODS
We collected automated data for 13,245 women enrolled at seven integrated healthcare delivery systems in the Cancer Research Network. All women were aged >55 and diagnosed with estrogen receptor positive, invasive breast cancer between 1996 and 2003. We used electronic pharmacy data to identify aromatase inhibitor and tamoxifen dispensings through 2004. We evaluated the proportions of women who received hormone dispensings in two ways: (1) at any point after diagnosis to capture all use, and (2) in the two-year period following diagnosis to approximate adjuvant use.


RESULTS
Over time, adjuvant aromatase inhibitor use increased whereas tamoxifen use decreased. Aromatase inhibitor dispensings within 2 years of diagnosis increased from 4.1% among women diagnosed in 2000 to 13% in 2001, 24% in 2002, and 40% in 2003. Tamoxifen use declined starting in 2001 at every system.


CONCLUSIONS
Aromatase inhibitor use rose dramatically after 2001 while tamoxifen use decreased. It appears results from early clinical trials changed practice in these integrated healthcare systems before formal changes in national guidelines.
Aiello
Erin J
EJ
Group Health Center for Health Studies, 1730 Minor Ave, Suite 1600, Seattle, WA 98101, USA. aiello.e@ghc.org
Buist
Diana S M
DS
Wagner
Edward H
EH
Tuzzio
Leah
L
Greene
Sarah M
SM
Lamerato
Lois E
LE
Field
Terry S
TS
Herrinton
Lisa J
LJ
Haque
Reina
R
Hart
Gene
G
Bischoff
Kimberly J
KJ
Geiger
Ann M
AM
D000368:Aged; D047072:Aromatase Inhibitors / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000188:drug therapy*; D005260:Female; D006801:Humans; D008875:Middle Aged; D013629:Tamoxifen / Q000627:therapeutic use; D013997:Time Factors; D014481:United States
D047072:Aromatase Inhibitors; D013629:Tamoxifen