Skeletal response to clodronate in prostate cancer with bone metastases

Bisphosphonates in Oncology: Physiopathologic Bases and Clinical Activity

Osteoclastic activation is the ultimate way of bone resorption in neoplasia, induced by the combined effects of tumor-secreted humoral factors (especially parathyroid hormone-related peptides) and osteoclastic-osteoblastic interaction. Bisphosphonates inhibit the osteoclast activity and reduce bone resorption and are a valuable supportive measure for bone disease of neoplasms. Experimental models also suggest an activity of bisphosphonates against cancer cells. Controlled studies, especially in advanced breast cancer and multiple myeloma, indicate different effectiveness against the distinct skeletal-related events. Intravenous clodronate and, especially, pamidronate and zoledronate are the first-choice drugs for hypercalcemia, and they play a significant role in reducing metastatic bone pain. Their prolonged use delays, without hampering, the progression of bone disease, including the appearance of osteolysis and the occurrence of pathologic fractures. This effect is probably more valuable when bisphosphonates are administered early in the course of the disease. The evidence that adjuvant bisphosphonates improve survival needs to be confirmed in ongoing studies. Although poorly absorbed by the gastrointestinal tract, oral bisphosphonates are effective in preventing and treating cancer-induced osteoporosis in long-living patients with operable breast cancer. At present, there is little hope that newer bisphosphonates are more effective than those currently used.

Bisphosphonates for advanced prostate cancer

BACKGROUND

The prevalence and incidence of pain and skeletal complications of metastatic bone disease such as pathologic fractures, spinal cord compression and hypercalcemia is high and an important contributor to morbidity, poor performance status and decreased quality of life. Moreover, pathologic fractures are associated with increased risk of death in people with disseminated malignancies. Therefore, prevention of pain and fractures are important goals in men with prostate cancer at risk for skeletal complications.

OBJECTIVES

To assess the effects of bisphosphonates in men with bone metastases from prostate cancer.

SEARCH METHODS

We identified studies by electronic search of bibliographic databases including the Cochrane Controlled Trials Register and MEDLINE on 13 July 2017 and trial registries. We handsearched the Proceedings of American Society of Clinical Oncology (to July 2017) and reference lists of all eligible trials identified. This is an update of a review last published in 2006.

SELECTION CRITERIA

We included randomized controlled studies comparing the effectiveness of bisphosphonates in men with bone metastases from prostate cancer.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the quality of trials. We defined the proportion of participants with pain response as the primary end point; secondary outcomes were skeletal-related events, mortality, quality of life, adverse events, analgesic consumption and disease progression. We assessed the quality of the evidence for the main outcomes using the GRADE approach.

MAIN RESULTS

We included 18 trials reporting on 4843 participants comparing the effect of bisphosphonate administration to control regimens.

PRIMARY OUTCOME

there was no clear difference in the proportion of participants with pain response (RR 1.15, 95% CI 0.93 to 1.43; P = 0.20; I² = 0%; 3 trials; 876 participants; low quality evidence). In absolute terms, bisphosphonates resulted in a pain response in 40 more participants per 1000 (19 fewer to 114 more).

SECONDARY OUTCOMES

bisphosphonates probably reduced the incidence of skeletal-related events in participants with prostate cancer metastatic to bone (RR 0.87, 95% CI 0.81 to 0.94; P = 0.27; I² = 19%; 9 trials; 3153 participants; moderate quality evidence). In absolute terms, bisphosphonates resulted in 58 fewer SREs per 1000 (85 fewer to 27 fewer).We found no clinically relevant differences in mortality (RR 0.97, 95% CI 0.91 to 1.04; P = 0.43; I² = 1%; 9 trials; 2450 participants; moderate quality evidence). In absolute terms, bisphosphonates resulted in 16 fewer deaths per 1000 (47 fewer to 21 more).Outcome definition of quality of life and the measurement tools varied greatly across trials and we were unable to extract any quantitative data for meta-analysis.Bisphosphonates probably increased the number of participants affected by nausea (RR 1.19, 95% CI 1.00 to 1.41; P = 0.05; I² = 0%; 9 trials; 3008 participants; moderate quality evidence). In absolute terms, bisphosphonates resulted in seven more cases of nausea per 1000 (0 fewer to 14 more). Bisphosphonates probably increased the number of renal adverse events (RR 1.65, 95% CI 1.11 to 2.46; P = 0.01; I² = 0%; 7 trials; 1794 participants; moderate quality evidence). In absolute terms, bisphosphonates resulted in 22 more renal adverse events per 1000 (4 more to 50 more). We found no clear difference in the number of participants with osteonecrosis of the jaw between groups (RR 1.92, 95% CI 0.75 to 4.90; P = 0.17; I² = 0%; 5 trials; 1626 participants; very low quality evidence). In absolute terms, bisphosphonates resulted in seven more cases with osteonecrosis of the jaw per 1000 (2 fewer to 29 more). We observed no clinically relevant difference in the proportion of participants with decreased analgesic consumption (RR 1.19, 95% CI 0.87 to 1.63; P = 0.28; I² = 37%; 4 trials; 416 participants). Statistical analysis revealed that bisphosphonates probably reduced the number of participants with disease progression (RR 0.94, 95% CI 0.90 to 0.98; P = 0.006; I² = 0%; 7 trials; 2115 participants; moderate quality evidence). In absolute terms, bisphosphonates resulted in 36 fewer cases of disease progression per 1000 (71 fewer to 7 fewer).Findings of our predefined subgroup and sensitivity analyses were no different from those of the primary analyses.

AUTHORS' CONCLUSIONS

Based on low quality evidence, there may be no clinically relevant difference in the proportion of men with pain response between bisphosphonates and control regimens in men with bone metastases from prostate cancer. Bisphosphonates probably decrease the number of skeletal-related events and disease progression. These benefits need to be weighed against the increased risk of renal impairment and nausea in men receiving bisphosphonates. Future studies should explicitly evaluate patient important outcomes such as quality of life and pain by using standardized and comparable assessment tools.

Quality of life measurement in bone metastases: A literature review

Quality of life (QOL) has become an important consideration in the care of patients with bone metastases as prevalence, incidence and patient survival are on the rise. As a result, more interventional studies now measure patient’s QOL as a meaningful endpoint. However, well-developed bone metastases specific quality of life instruments are lacking. A literature review was conducted to better understand the nature of QOL instruments used in bone metastases trials. A total of 47 articles evaluating QOL in patients with bone metastases were identified. Twenty-five different instruments were used to evaluate QOL with study-designed questionnaires and the EORTC QLQ-C30 being most commonly employed. Many studies used more than one scale or instrument to measure QOL. This makes it difficult to compare QOL in bone metastases patients across studies and come to any formal conclusions. Therefore, this review demonstrates the need to develop a bone module that can be used across countries in future clinical trials.

New trends in the treatment of bone metastasis

Bone metastasis is often the penultimate harbinger of death for many cancer patients. Bone metastases are often associated with fractures and severe pain resulting in decreased quality of life. Accordingly, effective therapies to inhibit the development or progression of bone metastases will have important clinical benefits. To achieve this goal understanding the mechanisms through which bone metastases develop and progress may provide targets to inhibit the metastases. In the past few years, there have been advances in both understanding the mechanisms through which bone metastases develop and how they impact bone remodeling. Additionally, gains in promising clinical strategies to target bone metastases have been developed. In this prospectus, we will discuss some of these advances.

Oral sodium clodronate for nonmetastatic prostate cancer--results of a randomized double-blind placebo-controlled trial: Medical Research Council PR04 (ISRCTN61384873)

BACKGROUND

The most frequent site of metastases from prostate cancer is bone. Adjuvant bisphosphonate treatment improves outcomes of patients with bone metastasis-negative breast cancer, but the effects of bisphosphonates on bone metastases in prostate cancer are not known.

METHODS

We performed a randomized double-blind placebo-controlled trial to determine whether a first-generation bisphosphonate could improve symptomatic bone metastasis-free survival (time to symptomatic bone metastases or death from prostate cancer) in men with nonmetastatic prostate cancer who were at high risk of developing bone metastases. Between June 1, 1994, and December 31, 1997, 508 men from 26 UK sites and one New Zealand site who were within 3 years of initial prostate cancer diagnosis with no evidence of metastases from current bone scanning were randomly assigned to daily oral sodium clodronate (2080 mg/day, n = 254) or placebo (n = 254) for a maximum of 5 years. Estimates of outcome risks were compared using Kaplan-Meier analyses.

RESULTS

The groups allocated to each treatment were well balanced. After a median follow-up of nearly 10 years, no evidence of benefit to the clodronate group was observed in terms of bone metastases-free survival (clodronate versus placebo, 80 events versus 68 events; hazard ratio [HR] = 1.22; 95% confidence interval [CI] = 0.88 to 1.68) or overall survival (clodronate versus placebo, 130 deaths versus 127 deaths; HR = 1.02; 95% CI = 0.80 to 1.30). Adverse events, notably gastrointestinal problems and increased lactate dehydrogenase levels, were more frequent in the clodronate group than in the placebo group; otherwise, clodronate was well tolerated. Modification of trial drug dose was more frequent in the clodronate group than the placebo group (HR = 1.63, 95% CI = 1.21 to 2.19).

CONCLUSION

Adjuvant sodium clodronate does not modify the natural history of nonmetastatic prostate cancer.

Bisphosphonates for advanced prostate cancer

BACKGROUND

Prostate cancer is the most common cancer in men in many western countries. It is characterized by its propensity for bone metastases which occur in more than 80% of patients with advanced disease. Patients are at risk of complications including pain, hypercalcaemia, bone fracture and spinal cord compression. Hormonal treatment is the mainstay of treatment for these patients but most of them will then become hormone refractory. Bisphosphonates act by inhibiting osteoclast activities and are a potential therapeutic option for metastatic prostate cancer. In addition, they have been shown to reduce pain in patients with bone metastases as a consequence of multiple myeloma. Early uncontrolled studies of bisphosphonates in metastatic prostate cancer patients have shown encouraging results.

OBJECTIVES

The objective of this review was to determine the effectiveness of bisphosphonates in relieving pain in patients with bone metastases from prostate cancer.

SEARCH STRATEGY

Studies were identified by electronic search of bibliographic databases including MEDLINE, EMBASE, CancerLit and the Cochrane Controlled Trials Register. Handsearching included Proceedings of American Society of Clinical Oncology and reference lists of all eligible trials identified.

SELECTION CRITERIA

Randomised controlled studies comparing the effectiveness of bisphosphonates with placebo or open control for pain relief in patients with bone metastases from prostate cancer.

DATA COLLECTION AND ANALYSIS

Data were extracted from eligible studies and included study design, participants, interventions and outcomes. Comparable data were pooled together for meta-analysis with intention-to-treat principle. Outcomes included pain response, analgesic consumption, skeletal events (including pathological fractures, spinal cord compression, bone radiotherapy, bone surgery), prostate cancer death, disease progression, radiological response, PSA response, adverse events, performance status, quality of life and comparisons between different routes, doses and types of bisphosphonates.

MAIN RESULTS

One thousand nine hundred and fifty-five patients from ten studies were included in this review. The pain response rates were 27.9% and 21.1% for the treatment group and the control group, respectively, with an absolute risk difference of 6.8%. The OR for pain response was 1.54 (95% CI 0.97 to 2.44, P = 0.07), showing a trend of improved pain relief in the bisphosphonate group, although this was not statistically significant. The rates for skeletal events were 37.8% and 43.0% for the treatment group and the control group, respectively, with an absolute risk difference of 5.2%. The OR for skeletal events was 0.79 (95% CI 0.62 to 1.00, P = 0.05). A significant increase in nausea was observed in patients who received bisphosphonates compared to placebo. No increase in other adverse events was observed. There was no statistically significant difference between the bisphosphonate group and the control group in terms of prostate cancer death, disease progression, radiological response and PSA response. There are insufficient data to guide the choice of bisphosphonates or the dose and the route of administration .

AUTHORS' CONCLUSIONS

Bisphosphonates should be considered for patients with metastatic prostate cancer for the treatment of refractory bone pain and prevention of skeletal events. More research is needed to guide the choice of bisphosphonates, optimal treatment schedule as well as cost-benefit comparisons. Combining results from different studies is difficult because different tools were used to assess pain, and also, bisphosphonates vary considerably in potency. This review highlights the need for standardisation and co-ordination among researchers in cancer pain studies.

The potential role of bisphosphonates as adjuvant therapy in the prevention of bone metastases

BACKGROUND

Bisphosphonates (BPs) reduce bone resorption rates by inhibiting osteoclast function, although direct antineoplastic effects and poorly understood effects on bone pain also may occur. Within the family of BPs there are more similarities in pharmacologic effects than differences, although side effect profiles, rates of oral absorption, and potency do differ. Oral clodronate and intravenous pamidronate reduce skeletal complications in patients with bone metastases from breast carcinoma (as well as in myeloma). Uncontrolled trials of prostate carcinoma also suggest clinical benefit.

METHODS

Animal studies show that BPs can reduce the rate of development of bone metastases (for example, in Walker 256 carcinoma), but there is little evidence of an effect at nonosseous sites. The hypothesis that the growth of subclinical osseous metastases is augmented by products of bone resorption (a "vicious cycle") and may be diminished by a local reduction of these substances has led to trials of BPs involving patients with no clinical evidence of bone metastases. These trials are critically assessed in this review.

RESULTS

In patients with recurrent breast carcinoma but no overt bone metastases, oral clodronate reduced the number of diagnosed bone metastases; but the number of patients who had relapses in bone, though smaller, was not significantly different from the number among patients who took placebo. In a trial of oral pamidronate, no effect was seen, but compliance was a problem because of gastrointestinal side effects. Patients treated for operable breast carcinoma have four or five times the normal rate of vertebral fracture, and BPs do reduce the rate of bone loss. Three adjuvant clodronate trials have been reported. The first, an open-label controlled trial (Diel et al.), showed a reduction in osseous and nonosseous recurrences and an increase in disease free and overall survival with 2 years of clodronate. A second open-label trial (Saarto et al.) of similar size involving lymph node positive breast carcinoma patients showed no effect on the rate of bone metastasis relapse and a deleterious effect on relapse rates of nonosseous metastases with 3 years of clodronate. A third placebo-controlled trial involving 1079 patients reported, in an interim analysis, a reduction in osseous metastases during treatment with 2 years of clodronate, but no effect on nonosseous metastases or survival.

CONCLUSIONS

A confirmatory clinical trial is required for two interrelated reasons: 1) scientifically, it is important to demonstrate that an agent that has its dominant effect on a normal tissue cell, the osteoclast, can influence the growth of neoplastic cells; and 2) from the perspective of patient care, it must be unequivocally shown that a reduction in the rate of osseous recurrence translates into an improvement in disease free survival or an improvement in quality of life through reduction of adverse skeletal events. The National Surgical Adjuvant Breast Project has committed to conducting this study and including women with operable breast carcinoma.

Essence of evidence-based medicine: A case report

PURPOSE

To illustrate the complexities of the evidence-based approach in clinical oncology practice and the implications for guidelines and evaluation of processes of care.

PATIENT AND METHODS

A case report is presented in which a limited systematic review of the literature was used to address a specific clinical problem in an individual patient. Experts' opinions were also sought.

RESULTS

A reasonable clinical decision was made by a participating patient based on indirect evidence of benefit that would be insufficient to support the same decision as a health policy in some jurisdictions.

CONCLUSION

The practice of evidence-based oncology requires clinical judgment about the validity and applicability of research evidence. The factors that influence an evidence-based decision in the clinical context differ from those in the broader policy context, which could lead to legitimate differences in recommendations based on the same information. Used properly, the individual case report can be a powerful tool to illustrate complex clinical decision phenomena.