Management of anastrozole-induced bone loss in breast cancer patients with oral risedronate: results from the ARBI prospective clinical trial.
BACKGROUND
The aim of this multicenter, phase III, prospective open label clinical trial was to investigate the effect of risedronate (R) on bone mineral density (BMD) in postmenopausal, early breast cancer (BC) patients scheduled to receive anastrozole (A).


METHODS
Pre-treatment BMD of 213 patients with hormone receptor-positive BC was evaluated at lumbar spine (LS) and hip (HP). Patients were categorized according to their baseline BMD T-score as being at low, moderate and high risk of osteoporosis. Low risk patients received anastrozole only (A), moderate risk were randomized to anastrozole +/- risedronate (A+/-R) administration and high risk patients received anastrozole + risedronate (A+R). Anastrozole was given at a dosage of 1 mg/day while oral risedronate was given at 35 mg/week. BMD was then assessed at 12 and 24 months. All patients received daily supplements of calcium (1000 mg/day) and vitamin D (400 IU/day).


RESULTS
At 24 months, in the moderate risk group, treatment with A+R resulted in a significant increase in BMD at LS and HP compared to treatment with A only (5.7% v -1.5%, Wilcoxon test P = 0.006, and 1.6% v -3.9% Wilcoxon test P = 0.037, respectively), while no significant difference was found at 12 months; 24.3% of the patients moved to normal BMD region. In the high risk group, a significant increase for LS was detected both at 12 and 24 months (6.3% and 6.6%, P < 0.001) but not for HP; BMD in 14% of patients improved to the osteopenic region. In the low risk group, a significant decrease of BMD was detected at 12 months for LS and HP (-5.3% P < 0.001 and -2.4% P < 0.001, respectively,); at 24 months, a significant decrease of BMD was detected only for LS (-2.5%, P < 0.001). However, 22% of patients became osteopenic and only 4% became osteoporotic.


CONCLUSIONS
The addition of oral risedronate in post-menopausal breast cancer patients receiving anastrozole has a favorable effect on BMD. Patients with pre-treatment osteopenic to osteoporotic status should be treated with a combination of both therapies in order to avoid bone loss induced by aromatase inhibition. Patients with normal BMD before starting treatment with anastrozole have a very low risk to develop osteoporosis.
Markopoulos
Christos
C
Hellenic Society of Breast Surgeons, 6 Eslin Street, Athens, Greece. cmarkop@hol.gr
Tzoracoleftherakis
Evagelos
E
Polychronis
Athanassios
A
Venizelos
Basileios
B
Dafni
Urania
U
Xepapadakis
Grigorios
G
Papadiamantis
John
J
Zobolas
Vasilios
V
Misitzis
John
J
Kalogerakos
Kyriakos
K
Sarantopoulou
Angeliki
A
Siasos
Nikolaos
N
Koukouras
Dimitrios
D
Antonopoulou
Zoh
Z
Lazarou
Spyros
S
Gogas
Helen
H
D000284:Administration, Oral; D000368:Aged; D000077384:Anastrozole; D047072:Aromatase Inhibitors / Q000009:adverse effects / Q000627:therapeutic use; D018771:Arthralgia / Q000139:chemically induced; D015519:Bone Density / Q000187:drug effects; D050071:Bone Density Conservation Agents / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000188:drug therapy*; D004359:Drug Therapy, Combination; D004415:Dyspepsia / Q000139:chemically induced; D012968:Etidronic Acid / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008875:Middle Aged; D009325:Nausea / Q000139:chemically induced; D009570:Nitriles / Q000009:adverse effects / Q000627:therapeutic use*; D015663:Osteoporosis, Postmenopausal / Q000139:chemically induced / Q000517:prevention & control*; D010352:Patient Dropouts / Q000706:statistics & numerical data; D011446:Prospective Studies; D000068296:Risedronic Acid; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D014230:Triazoles / Q000009:adverse effects / Q000627:therapeutic use*
D047072:Aromatase Inhibitors; D050071:Bone Density Conservation Agents; D009570:Nitriles; D014230:Triazoles; D000077384:Anastrozole; D000068296:Risedronic Acid; D012968:Etidronic Acid
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