SKELETAL FRACTURE ASSOCIATED WITH ANDROGEN SUPPRESSION INDUCED OSTEOPOROSIS: THE CLINICAL INCIDENCE AND RISK FACTORS FOR PATIENTS WITH PROSTATE CANCER

Evaluation of Load-To-Strength Ratios in Metastatic Vertebrae and Comparison With Age- and Sex-Matched Healthy Individuals

Vertebrae containing osteolytic and osteosclerotic bone metastases undergo pathologic vertebral fracture (PVF) when the lesioned vertebrae fail to carry daily loads. We hypothesize that task-specific spinal loading patterns amplify the risk of PVF, with a higher degree of risk in osteolytic than in osteosclerotic vertebrae. To test this hypothesis, we obtained clinical CT images of 11 cadaveric spines with bone metastases, estimated the individual vertebral strength from the CT data, and created spine-specific musculoskeletal models from the CT data. We established a musculoskeletal model for each spine to compute vertebral loading for natural standing, natural standing + weights, forward flexion + weights, and lateral bending + weights and derived the individual vertebral load-to-strength ratio (LSR). For each activity, we compared the metastatic spines' predicted LSRs with the normative LSRs generated from a population-based sample of 250 men and women of comparable ages. Bone metastases classification significantly affected the CT-estimated vertebral strength (Kruskal-Wallis, p < 0.0001). Post-test analysis showed that the estimated vertebral strength of osteosclerotic and mixed metastases vertebrae was significantly higher than that of osteolytic vertebrae (p = 0.0016 and p = 0.0003) or vertebrae without radiographic evidence of bone metastasis (p = 0.0010 and p = 0.0003). Compared with the median (50%) LSRs of the normative dataset, osteolytic vertebrae had higher median (50%) LSRs under natural standing (p = 0.0375), natural standing + weights (p = 0.0118), and lateral bending + weights (p = 0.0111). Surprisingly, vertebrae showing minimal radiographic evidence of bone metastasis presented significantly higher median (50%) LSRs under natural standing (p < 0.0001) and lateral bending + weights (p = 0.0009) than the normative dataset. Osteosclerotic vertebrae had lower median (50%) LSRs under natural standing (p < 0.0001), natural standing + weights (p = 0.0005), forward flexion + weights (p < 0.0001), and lateral bending + weights (p = 0.0002), a trend shared by vertebrae with mixed lesions. This study is the first to apply musculoskeletal modeling to estimate individual vertebral loading in pathologic spines and highlights the role of task-specific loading in augmenting PVF risk associated with specific bone metastatic types. Our finding of high LSRs in vertebrae without radiologically observed bone metastasis highlights that patients with metastatic spine disease could be at an increased risk of vertebral fractures even at levels where lesions have not been identified radiologically.

Risk of new-onset diabetes mellitus and worsening glycaemic variables for established diabetes in men undergoing androgen-deprivation therapy for prostate cancer

OBJECTIVE To investigate the incidence of new-onset diabetes mellitus (NODM) and of worsening glycaemic control in established DM after starting androgen-deprivation therapy (ADT) for prostate cancer, as ADT is associated with altered body composition, potentially influencing insulin sensitivity. PATIENTS AND METHODS We retrospectively reviewed patients receiving ADT for prostate cancer at our institution between January 1989 and July 2005; those with incomplete information and those receiving only neoadjuvant ADT were excluded. Variables examined included age, race, body mass index (BMI), pretreatment prostate-specific antigen, Gleason sum, clinical stage, ADT type (medical vs surgical) and schedule (continuous vs intermittent), presence of pre-existing DM, serum glucose and glycosylated haemoglobin (HbA1c) levels before and after ADT, and receipt of vitamin D or bisphosphonate supplementation. Data were analysed statistically and P < 0.05 considered to indicate significance. RESULTS In all, 396 patients (median age 73.2 years; median BMI of 26.7 kg/m(2) at ADT initiation) were analysed. Of these, 59.1% were African-American and 40.9% were Caucasian/other. At a median follow-up of 60.1 months, 36 (11.3%) patients developed NODM. In 77 patients with pre-existing DM, there was an increase of >/=10% in serum HbA1c or fasting glucose levels in 15 (19.5%) and 22 (28.6%), respectively. On multivariate analysis, a BMI of >/=30 kg/m(2) was associated with an increased risk of developing NODM (odds ratio 4.65, P = 0.031). Receipt of vitamin D had a protective effect (odds ratio 5.75, P = 0.017). CONCLUSIONS Patients receiving ADT for prostate cancer with or with no history of DM should have routine surveillance of glycaemic control, particularly when their BMI is >/= 30 kg/m(2), with appropriate preventive and treatment measures.

Cancer treatment-induced bone loss in patients with breast or prostate cancer

PURPOSE/OBJECTIVES

To review the prevalence, consequences, pathophysiology, diagnosis, and treatment of cancer treatment-induced bone loss (CTIBL) in patients with breast or prostate cancer.

DATA SOURCES

Published articles, abstracts, book chapters, electronic resources, and manufacturer information.

DATA SYNTHESIS

CTIBL is a long-term complication associated with cancer therapies that cause hypogonadism in patients with breast or prostate cancer. Early diagnosis and treatment of CTIBL is essential to prevent bone fractures. CTIBL treatment includes modification of lifestyles that increase the risk of developing bone loss and fractures and includes the use of bone loss therapies (e.g., bisphosphonates, selective estrogen receptor modifiers, calcitonin).

CONCLUSIONS

CTIBL is becoming more common as patients with breast or prostate cancer survive longer. Identifying and treating CTIBL early are important because once bone is lost, damaged bone becomes more difficult to repair; early diagnosis and treatment also may prevent fractures.

IMPLICATIONS FOR NURSING

Nurses must be knowledgeable about CTIBL to identify high-risk patients and educate patients and their families about CTIBL, bone loss therapies, and lifestyle modifications.

Bisphosphonates in the management of metastatic prostate cancer

Prostate cancer (PCA) frequently metastasizes to the bones, and skeletal metastases represent the most common cause of morbidity in advanced PCA. Besides the development of skeletal events due to metastases, patients with PCA are at higher risk for benign osseous complications, such as osteoporosis and fractures. Bisphosphonates (BPs) have emerged as an integral part of the management of skeletal disease related to PCA. Currently available data support their routine use to prevent androgen-deprivation-induced osteoporosis and its secondary complications. Dosing at 3-month intervals is appropriate; further studies will have to demonstrate the efficacy of annual dosing. In men with already established bone metastases, BPs might be helpful in preventing skeletal-related events in patients who do not respond to alternative therapies and are at high risk for bone fractures or spinal cord compression. In patients with hormone-refractory prostate cancer, BPs might be administered for analgesic purposes. Prospective randomized trials will have to explore the clinical role of BPs in the prevention of bone metastases following local therapy with curative intent in men at high risk for PCA recurrences.