The effect of tamoxifen or exemestane on bone mineral density during the first 2 years of adjuvant treatment of postmenopausal women with early breast cancer.
BACKGROUND
Adjuvant therapy with aromatase inhibitors is associated with increased bone loss in postmenopausal women with breast cancer. We assessed changes in bone mineral density (BMD) from baseline to 24 months in patients receiving either tamoxifen (T) or exemestane (E).


METHODS
A total of 578 women randomly assigned to T 20 mg per day orally or E 25 mg/day orally enrolled in this substudy; baseline, 12-month, and 24-month BMD measurements of the femur and lumbar spine by dual-energy x-ray absorptiometry were planned. Women receiving bone antiresorptive agents were excluded. Mean BMD changes from baseline to 12 and 24 months were tested between the treatment groups using 2-sample t tests and both g/cm2 (as percent changes) and T scores (as differences from baseline).


RESULTS
A total of 167 women with all 3 imaging studies were evaluable and form the basis of this report (T=89, E=78). Using T scores, the mean difference from baseline was significant between the 2 groups at 12 months at both the spine (P=.0002) and the hip (P=.0004), and at 24 months only at the hip (P=.02).


CONCLUSIONS
More bone loss occurred during the first 12 months of treatment with E compared with T, but by 2 years the differences were less apparent and bone loss with E had slowed.
Jones
Stephen
S
US Oncology Research, Inc., Houston, TX, USA. steve.jones@usoncology.com
Stokoe
Christopher
C
Sborov
Mark
M
Braun
Marcus
M
Ethirajan
Sukumar
S
Kutteh
Leila
L
Pippen
John
J
Patel
Mrugesh
M
Paul
Devchand
D
Blum
Joanne L
JL
Holmes
Frankie Ann
FA
Myron
Mark C
MC
Cantrell
James
J
Hartung
Nichole L
NL
Look
Regan M
RM
Di Salle
Enrico
E
Davis
Jennifer C
JC
Ilegbodu
Des
D
Asmar
Lina
L
D015502:Absorptiometry, Photon; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000730:Androstadienes / Q000009:adverse effects / Q000627:therapeutic use*; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use*; D047072:Aromatase Inhibitors / Q000009:adverse effects / Q000627:therapeutic use*; D015519:Bone Density / Q000187:drug effects*; D001943:Breast Neoplasms / Q000188:drug therapy / Q000473:pathology; D017024:Chemotherapy, Adjuvant; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008875:Middle Aged; D010024:Osteoporosis / Q000139:chemically induced / Q000175:diagnosis; D017698:Postmenopause; D013629:Tamoxifen / Q000627:therapeutic use*
D000730:Androstadienes; D018931:Antineoplastic Agents, Hormonal; D047072:Aromatase Inhibitors; D013629:Tamoxifen; C056516:exemestane