Optimal bone health management strategies in patients with prostate cancer

A prospective longitudinal study to evaluate bone health, implication of FRAX tool and impact on quality of life (FACT-P) in advanced prostate cancer patients

BACKGROUND

Androgen-deprivation therapy (ADT) as a treatment modality in advanced prostate cancer has deleterious effect on bone mineral density (BMD) and quality of life (QOL). Using FRAX (Fracture Risk Assessment) model, candidates at high risk of fractures can be predicted and appropriate treatment can be initiated at early step to prevent skeletal-related events. Objectives of the present study were to evaluate bone health, implication of FRAX tool in advanced prostate cancer and to see the impact of ADT and Bone-directed therapy (BDT) on FRAX and FACT-P QOL scores.

MATERIAL & METHOD

We conducted a prospective longitudinal study of 83 localized and metastatic prostate cancer patients from March 2017 to Dec 2020. FRAX tool using BMD femoral neck (GE-Lunar) was used to compute the probability of 10-year Major osteoporotic fracture (MOF) and hip fracture risk %. Patients who received monthly Zolendronic acid with or without Vitamin-D/calcium supplementation were classified as BDT group. FRAX and FACT-P were measured at baseline and 12 months follow-up and compared between different therapeutic modalities to see the impact on clinical outcomes.

RESULTS

Majority of patients had skeletal metastasis (78.3%) and high-grade disease at presentation. Secondary osteoporosis was the most commonly (82.05%) observed clinical risk factor (CRF) followed by smoking (19.23%). Hip fracture risk ≥3% accounted for larger proportion of patients than did MOF risk ≥20% (21.2% and 2.5%, respectively). Statistically significant reduction was observed in both MOF and hip fracture risk in BDT group, while worsening on ADT. ADT duration correlated positively with both MOF and hip fracture risk (R2=0.148, P<0.001 and R2=0.164, P<0.001, respectively). FRAX score accurately predict future fracture events in majority (80%) of high-risk patients. Statistically and clinically significant worsening in PWB, EWB, PCS, FACT-P Total, FACT-P TOI and FAPSI scores were observed in patients on ADT. Statistically and clinically significant improvement was noted in physical well-being in BDT group. However, other QOL domains and FACT-P total scores remained stable.

CONCLUSIONS

ADT caused duration depended worsening of FRAX and FACT-P score in these patients while improvements of FRAX were seen on BDT. FRAX tool is advantageous in identifying the patients who require early intervention or therapy to decrease skeletal-related events.

Implications of the Fracture Risk Assessment Algorithm for the assessment and improvement of bone health in patients with prostate cancer: A comprehensive review

OBJECTIVE

Maintaining the optimum bone health is one of the important concerns in patients with prostate cancer, but it usually remains neglected. Failure to screen these patients is detrimental to both the length and the quality of life. The estimation of bone mineral density (BMD) and more recently the World Health Organization's fracture risk assessment (FRAX) algorithm in appropriate patients is recommended by several specialty organizations/associations at the time of instituting androgen deprivation therapy (ADT) for metastatic and high-risk individuals. It provides a 10-year risk evaluation of hip and major osteoporotic fractures (MOF). Using this web-based new investigating tool, candidates at high risk of fractures can be predicted more accurately according to clinical risk factors (CRF) alone or in combination with the femoral neck BMD. The FRAX application for senile osteoporosis has been studied and reviewed extensively, but no systematic review has ever been conducted for assessing the implication of FRAX in prostate cancer. This review article will give insight about the validity, role, and utility of this investigating tool in clinical practice for fracture risk assessment in these individuals.

MATERIAL AND METHODS

This systematic review was carried out as per the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines and Cochrane review principles. We searched the PubMed, Cochrane database of systematic reviews, and the EMBASE electronic database until December 2018 using the medical subject heading terms prostate cancer and FRAX.

RESULTS

A total of nine studies meet the inclusion criteria and were included in the review. These studies enrolled a total of 3704 patients (sample size range, 78-1220) of localized, metastatic, castration resistant prostate cancer with or without ADT and/or on photon or radiotherapy. The factors that influenced FRAX included age, ethnicity, baseline BMD, duration of ADT, presence of CRF, and measurement methods (CRF, with/without BMD, computed tomography based). An advanced age and duration of ADT were the most robust risk factors. A 10-year MOF and hip fracture risk estimation was higher when the femoral neck BMD was not incorporated in the FRAX measurement. Despite several well-known strengths of using FRAX in the fracture risk assessment of suitable candidates with prostate cancer, several risk factors such as the mode/duration of ADT, mode of radiotherapy, Vitamin D levels, bone remodeling markers, and recent/recurrent fractures need to be incorporated in the FRAX calculator for improving the predictive ability. In contrast to senile osteoporosis with a longer life expectancy, the fracture risk in patients with prostate cancer need to be measured more frequently and for a shorter time. Therefore, models like Garvan calculator with both 5- and 10-year risk estimates have to be developed for these patients. Additionally, its utilization is of limited value in the presence of recurrent fractures or falls.

CONCLUSION

The FRAX algorithm is beneficial in identifying patients who require early intervention or bone-directed therapy as an early step to decrease skeletal-related events and other morbidity. Several risk factors need to be added for improving the FRAX predictive value. This model is still underutilized in the clinical practice and increasing the awareness among treating physicians will help in optimizing the bone health and the quality of life of this important population subgroup.

Recent advances in bone-targeted therapies of metastatic prostate cancer

Prostate cancer is one of the most common malignancies affecting men worldwide, with bone being the most common site of metastasis in patients that progress beyond organ confinement. Bone metastases are virtually incurable and result in significant disease morbidity and mortality. Bone provides a unique microenvironment whose local interactions with tumor cells offer novel targets for therapeutic interventions. Several attractive molecules or pathways have been identified as new potential therapeutic targets for bone metastases caused by metastatic castration-resistant prostate cancer. In this review, we present the recent advances in molecular targeted therapies for prostate cancer bone metastasis focusing on therapies that target the bone cells and the bone microenvironment. The therapies covered in this review include agents that inhibit bone resorption, agents that stimulate bone formation, and agents that target the bone matrix. Suggestions to devise more effective molecular targeted therapies are proposed. Hopefully, with better understanding of the biology of the disease and the development of more robust targeted therapies, the survival and quality of life of the affected individuals could be significantly improved.

Osteoporosis in men

Osteoporosis in men causes significant morbidity and mortality. Bone health declines gradually, often insidiously; and in light of the advancing aging population poses a serious public health issue that is not well recognized. Studies of the past decade have expanded our understanding of the events within, as well as the regulation of, bone remodeling and provided better insight into the physiology and pathophysiology specific to the adult male skeleton. The clinical measurement of bone mineral density using dual-energy X-ray absorptiometry remains the gold standard for diagnosis of osteoporosis in males; and fracture risk assessment is now recognized as a preferred approach to guide treatment decisions. Utilizing surrogate end-points such as increasing bone mineral density and decreasing concentrations of bone resorption markers, clinical trials have demonstrated efficacy in pharmacological treatment of osteoporosis in the adult male. Unfortunately, few studies have evaluated the anti-fracture benefits in this population. Measurement of bone turnover markers may be an additional tool to monitor therapeutic responsiveness in addition to the measurement of bone mineral density.

The osteoblastic and osteoclastic interactions in spinal metastases secondary to prostate cancer

Prostate cancer (PC) is one of the most common cancers arising in men and has a high propensity for bone metastasis, particularly to the spine. At this stage, it often causes severe morbidity due to pathological fracture and/or metastatic epidural spinal cord compression which, if untreated, inevitably leads to intractable pain, neurological deficit, and paralysis. Unfortunately, the underlying molecular mechanisms driving growth of secondary PC in the bony vertebral column remain largely unknown. Further investigation is warranted in order to identify therapeutic targets in the future. This review summarizes the current understanding of PC bone metastasis in the spine, highlighting interactions between key tumor and bone-derived factors which influence tumor progression, especially the functional roles of osteoblasts and osteoclasts in the bone microenvironment through their interactions with metastatic PC cells and the critical pathway RANK/RANKL/OPG in bone destruction.