Reducing unnecessary osteoporosis treatment in prostate cancer with FRAX‐BMD integration
Takashi Kawahara, Masanobu Yamazaki, Akihito Hashizume, Daiki Ueno, Yasuhide Miyoshi, Koichi Uemura, Yusuke Ito, Hiroki Ito, Kazuhide Makiyama, Jun‐ichi Teranishi, Hiroji UemuraABSTRACT
Background
Men on androgen deprivation therapy (ADT) for prostate cancer frequently develop osteoporosis, and up to 20% fracture within five years. The Fracture Risk Assessment Tool (FRAX) estimates 10‐year fracture probability with or without bone mineral density (BMD), but data in this population are scarce. We assessed how BMD changes the estimate.
Methods
Of 1220 patients with prostate cancer who completed the FRAX questionnaire, 131 underwent dual‐energy X‐ray absorptiometry (DEXA); 22 with missing data were excluded, leaving 109. In these patients, the probability was calculated twice, from clinical risk factors alone and after adding the femoral neck T ‐score, and then compared within patients.
Results
Adding BMD lowered the median probability from 7.9% to 5.1% for major osteoporotic fracture and from 2.6% to 0.9% for hip fracture (means 8.06% to 5.48% and 2.95% to 1.36%, both paired t ‐test p < 0.001). The proportion at or above the treatment threshold fell from 43.1% to 9.2% for hip fracture (McNemar exact p < 0.001) but not for major osteoporotic fracture (3.7% to 1.8%, p = 0.63). Of the 47 patients above the hip threshold, 40 (85.1%) fell below it. The reduction was associated with older age and higher T ‐score, not with ADT.
Conclusion
Adding femoral neck BMD to FRAX substantially lowers the estimated fracture probability and reclassifies most patients below the hip fracture treatment threshold. Targeted DEXA may therefore avoid pharmacotherapy that would be started on FRAX alone. Because fractures were not followed, whether the revised estimates are more accurate is undetermined.