Validation of JSBMR's CTIBL manual for Japanese men receiving androgen deprivation therapy for prostate cancer.

INTRODUCTION

Androgen deprivation therapy (ADT) for prostate cancer causes cancer treatment-induced bone loss (CTIBL), increases the fracture risk 2-3 times, and worsens life prognoses. The Japan Society of Bone and Mineral Research (JSBMR) created a CTIBL treatment manual in 2020; however, no study has validated its use in patients with ADT/CTIBL prostate cancer.

MATERIALS AND METHODS

This study classified 124 patients with prostate cancer without bone metastasis who received ADT into high- and low-risk groups using the JSBMR CTIBL algorithm. Comparisons were made with the period to incident vertebral fracture and the existing International Osteoporosis Foundation (IOF) classification.

RESULTS

The median age was 74 years; the median observation period was 81 months. At 1, 3, 5, 7, and 9 years, the prevalence of incident vertebral fractures was, respectively, 3.3%, 10.7%, 17.9%, 21.4%, and 31.2% in the entire population; 13%, 27%, 36%, 42%, and 58% in the high-risk group (19%); and 1%, 7%, 14%, 17%, and 25% in the low-risk group (81%). The hazard ratio between the two groups was 3.57 (p = 0.0004). Based on multivariate analysis, age, previous vertebral fracture and femoral neck bone density were significant risk factors for incidental vertebral fracture. The JSBMR had a hazard ratio of 3.26 (p = 0.04) relative to 1.13 (p = 0.84) for the IOF, indicating the JSBMR classification performed better.

CONCLUSION

Taking preventive measures against fractures is necessary, including starting bone-modifying agents early in patients with a high fracture risk. The JSBMR CTIBL manual may be useful for this purpose.