Treatment of bone metastases from breast cancer and myeloma with pamidronate

Bisphosphonates and breast cancer - From cautious palliation to saving lives

Bone metastases are common in breast cancer and may cause considerable morbidity including fractures, severe pain, nerve compression and hypercalcaemia. Alongside developments in the multidisciplinary management for patients with metastatic breast cancer, the use of bisphosphonates, and more recently denosumab, has transformed the course of advanced breast cancer for many patients resulting in a major reduction in skeletal complications, reduced bone pain and improved quality of life. Additionally, because the bone marrow microenvironment is so intimately involved in the metastatic processes required for cancer dissemination, the use of adjuvant bisphosphonates has been studied extensively over the past 25 years in many randomised trials. We now have clear evidence that bisphosphonates significantly reduce both metastasis to bone and mortality in postmenopausal women with early breast cancer. Efficacy seems similar across different biological subgroups of postmenopausal breast cancer with the use of either a nitrogen-containing bisphosphonate such as intravenous zoledronate or daily oral ibandronate as well as the non-nitrogen containing agent, daily oral clodronate. In this overview of evolving role of bisphosphonates in breast cancer, focussing particularly on pamidronate and zoledronate, the long winding development road from the 1970s through to the present day is described and some of the serendipitous findings, "lucky breaks" and regulatory decisions along the way outlined.

Role of Pamidronate Disodium in the Treatment of Metastatic Bone Disease

Aims and Background

Bone metastases are a common feature of advanced neoplastic disease and are considered to be among the most frequent causes of pain and complications in oncologic patients. The main objective of the treatment of such patients is to control their symptoms and improve their quality of life. Pamidronate disodium is a second-generation bisphosphonate capable of inhibiting bone resorption (particularly osteoclast activity) without affecting bone reminerali-zation. After a brief introduction concerning the pathophysiology of bone metastases and neoplastic bone pain, we herein present data on the clinical pharmacology and toxicity of bisphosphonates in general, and pamidronate in particular. We conclude by reviewing the literature on the use of pamidronate in phase II and III trials involving patients with metastatic bone disease.

Methods

The paper is based on a review of articles published between 1984 and 1997 selected from the Cancerline and Medline databases.

Results

In the considered phase II and III studies involving patients with bone metastases (breast cancer and multiple myeloma in particular), pamidronate proved to be efficacious in reducing the incidence of pain and skeletal complications, decreasing the excretion of metabolic markers of bone resorption and improving the quality of life. Intravenous infusions of 60-90 mg over a period of 2 hr every 3-4 weeks did not cause any significant toxic effects and was easily managed.

Conclusions

Pamidronate is a bisphosphonate that is efficacious in the treatment of symptomatic bone metastases and can be considered an important therapeutic option in association with systemic treatments, radiotherapy and normal supportive care, especially in patients with breast cancer and multiple myeloma. Further randomized studies are necessary to confirm the positive preliminary results in other neoplasms, analyze the cost/benefit ratio of the treatment, and verify the possibility that, in addition to being used for palliative purposes, pamidronate may also prevent or delay the appearance of bone metastases.

Receptor activator of nuclear factor kappaB ligand and osteoprotegerin regulation of bone remodeling in health and disease

Osteoclasts and osteoblasts dictate skeletal mass, structure, and strength via their respective roles in resorbing and forming bone. Bone remodeling is a spatially coordinated lifelong process whereby old bone is removed by osteoclasts and replaced by bone-forming osteoblasts. The refilling of resorption cavities is incomplete in many pathological states, which leads to a net loss of bone mass with each remodeling cycle. Postmenopausal osteoporosis and other conditions are associated with an increased rate of bone remodeling, which leads to accelerated bone loss and increased risk of fracture. Bone resorption is dependent on a cytokine known as RANKL (receptor activator of nuclear factor kappaB ligand), a TNF family member that is essential for osteoclast formation, activity, and survival in normal and pathological states of bone remodeling. The catabolic effects of RANKL are prevented by osteoprotegerin (OPG), a TNF receptor family member that binds RANKL and thereby prevents activation of its single cognate receptor called RANK. Osteoclast activity is likely to depend, at least in part, on the relative balance of RANKL and OPG. Studies in numerous animal models of bone disease show that RANKL inhibition leads to marked suppression of bone resorption and increases in cortical and cancellous bone volume, density, and strength. RANKL inhibitors also prevent focal bone loss that occurs in animal models of rheumatoid arthritis and bone metastasis. Clinical trials are exploring the effects of denosumab, a fully human anti-RANKL antibody, on bone loss in patients with osteoporosis, bone metastasis, myeloma, and rheumatoid arthritis.

Myeloma bone disease

The major clinical manifestation of multiple myeloma is related to the osteolytic bone destruction. The bone disease can lead to pathologic fractures, spinal cord compression, hypercalcemia, and pain. It is also a major cause of morbidity and mortality in these patients. These patients frequently require radiation therapy, surgery and analgesic medications. Bisphosphonates are specific inhibitors of osteoclastic activity, and these agents have been evaluated in myeloma patients with bone disease during the past 15 years. Several large randomized trials have been conducted in myeloma patients also receiving chemotherapy. Orally administered bisphosphonates have shown little ability to slow the development of skeletal complications in these patients. In contrast, more potent intravenous monthly infusions of either pamidronate or zoledronic acid have reduced the skeletal complications among these patients and are now a mainstay of myeloma therapy. A number of other types of new anti-bone-resorptive agents are also in early clinical development.

Duration of bisphosphonate treatment: results of a non-randomised study in patients previously treated with local irradiation for bone metastases from breast cancer

PURPOSE

To assess whether disodium pamidronate (DP) once started should be given life-long in women with lytic bone metastases.

PATIENTS AND METHODS

One hundred and three women with breast cancer who had at least one osteolytic lesion received 180 mg of DP as a 2-h intravenous infusion given every 4 weeks for a life-time, following local radiotherapy. After six cycles, 26 out of 103 patients (25%) refused to continue their bisphosphonate-treatment. Thus two groups were constituted: non-stop (group A) and premature discontinued (group B). The new skeletal complication free survival (NSCFS) was the primary endpoint verified during extramural review. Performance status, pain-score and biochemical markers were secondary endpoints.

RESULTS

Generally DP was well tolerated. At 36 months, the proportion of patients having had any skeletal complication was 54.5 and 84.6% in group A and B, respectively. The median time of NSCFS was apparently longer for group A. In group A, the pain score and the ECOG status were significantly lower, while the overall survival appeared to be longer. Multivariate analysis revealed age, nodal status and interruption of treatment as prognostic factors to NSCFS, with relative risk 1.05, 2.3 and 1.5 respectively.

CONCLUSION

Data concerning the suspension of new skeletal complications, as well as the apparent improvement of overall survival, pain score and ECOG status, suggest that the pamidronate-treatment should not be stopped once started. These results should be confirmed in a randomised trial.

Clinical and economic issues in the treatment of advanced breast cancer with bisphosphonates

An ideal palliative therapy for bone metastases would successfully reduce skeletal complications in several thousands of breast cancer patients. Second- and third-generation bisphosphonates are effective in reducing the overall skeletal complication rate and the time to first skeletal complication. Nevertheless, not enough evidence supports their benefit on quality of life. Furthermore, bisphosphonates are expensive (up to 775 US dollars per month, 2002 value) and cost-effectiveness evaluations have been limited to pamidronate (pamidronic acid). In economic evaluations of pamidronate, resulting incremental dollar per quality-adjusted life year gained ranged from cost savings to 108,000 US dollars per quality-adjusted life year. The data were quite sensitive to quality-of-life estimates and country-specific cost values. Because of the wide range of the cost-effectiveness ratio, it is uncertain whether the universal prescription of bisphosphonates in this setting represents an efficient use of healthcare resources. Probably, country- and drug-specific policies might increase the efficiency of this treatment. Further outcomes research is required to assess these agents more fully.

Strategies for management of prostate cancer-related bone pain

Prostate cancer is one of the most common malignancies and a leading cause of cancer-related death in men worldwide. In the majority of cases, prostate cancer metastases to the skeleton, in which case cancer-related bone pain becomes a major cause of morbidity. Androgen ablation is the treatment of choice for securing regression of skeletal metastases in the majority of cases. Intermittent androgen ablation is an attractive alternative, aimed at minimising adverse effects of hormone deprivation but also potentially delaying hormone-refractoriness. The development of hormone-refractoriness is heralded by a significant increase in morbidity largely because of escalating bone pain caused by the progression of the metastatic process. Skillful use of analgesics is initially successful but eventually fails to control symptoms. Localised metastases are best treated with local radiotherapy that is rapidly effective. Over the last few years, it has become clear that therapeutic modalities using bone-seeking radionuclides or bisphosphonates have been effective in the palliation of prostate cancer-related bone pain, although not affecting survival. The main limiting factor with the use of radionuclides is bone marrow suppression, also a feature of the very late stages of prostate cancer. Bisphosphonates do not carry this disadvantage. Results of large double-blind, placebo-controlled studies should be awaited, however, before advocating the widespread use of these agents in the management of patients with prostate cancer and skeletal metastases.

Bone mineral density in multiple myeloma patients after intravenous clodronate therapy

Bisphosphonates inhibit osteoclastic bone destruction that may be stimulated by myeloma cells. By this way, bisphosphonates carry the potential to lower the number of new pathological fractures, of hypercalcaemic events, and of intensity of bone pain as was published earlier. Clodronate has been administered orally in most clinical studies so far despite of its poor bioavailability from the gastrointestinal tract. The aim of our study was to evaluate bone mineral density (BMD) changes in 34 newly diagnosed multiple myeloma patients regularly treated by 900 mg of clodronate in slow intravenous infusions on an outpatient basis in two-week intervals for at least 24 months. BMD was evaluated by CT scanning every six months. Initial values of trabecular BMD were only about 60 per cent of age- and sex-adjusted healthy population values. Clodronate therapy seemed to preserve BMD within the period of two or three years. This effect was seen not only in patients responding to chemotherapy but even in the small subgroup of patients with persisting active disease. We conclude that the long-term intravenous clodronate therapy may contribute to the preservation of BMD and thus calcium hydroxyapatite in bones in multiple myeloma patients concomitantly treated by chemotherapy. The administration of clodronate should start early in the course of disease, before BMD has been markedly reduced.

Bone disease in myeloma

The major clinical manifestation of multiple myeloma results from osteolytic bone destruction. The only currently Food and Drug Administration-approved drug for the treatment of the bony complications of multiple myeloma is monthly intravenous pamidronate at a dose of 90 mg infused over 4 hours. Recent studies have shown the safety of 2-hour infusions. A randomized trial comparing pamidronate to placebo continued to show benefits throughout the 21-month trial. Although the duration of therapy has not been firmly determined, it is likely that discontinuation of this drug will be met by enhanced bone loss and an increased risk of bony complications for these patients. Thus, it is recommended that the drug be continued indefinitely. Support for this recommendation also comes from the reduced bone density observed in women with postmenopausal osteoporosis following the withdrawal of bisphosphonate treatment. Recent attempts to give higher doses, more frequent infusions (every 2 weeks or less), or more rapid infusions (1 hour or less) of pamidronate have occasionally been associated with albuminuria and azotemia. These modifications should therefore be avoided. Importantly, the drug can be safely administered at 90 mg monthly to patients with poor renal function. The use of pamidronate for myeloma patients without lytic bone involvement or with Durie-Salmon stages I or II disease has not been evaluated. However, it is recognized that most patients with earlier stages of disease or without lytic bone involvement also develop bony complications. There is no reason to believe that these patients would not benefit from monthly intravenous infusions of pamidronate. The potential antimyeloma effect of this agent is another reason to administer this drug in these types of patients. Thus, it is our practice to administer monthly pamidronate to myeloma patients regardless of stage or bone involvement. However, trials evaluating oral bisphosphonates have produced inconsistent clinical results, probably as a result of the erratic and scanty poor absorption as well as poor oral tolerability of these drugs. Although these oral agents may be useful in some patients, it is impossible to identify which myeloma patients will benefit from orally administered bisphosphonates. The more potent nitrogen-containing bisphosphonate zoledronic acid more effectively reverses hypercalcemia of malignancy than pamidronate, and it appears promising in reducing bone loss in cancer patients. However, its efficacy in preventing skeletal complications is still being evaluated. Many other types of new agents are in early clinical trials, but their efficacy remains unproven at the present time.

Bisphosphonates regulate cell growth and gene expression in the UMR 106-01 clonal rat osteosarcoma cell line

Local growth of osteosarcoma involves destruction of host bone by proteolytic mechanisms and/or host osteoclast activation. Osteoclast formation and activity are regulated by osteoblast-derived factors such as the osteoclast differentiating factor, receptor activator of NF-kappaB ligand (RANKL) and the inhibitor osteoprotegerin (OPG). We have investigated the in vitro effects of bisphosphonates on a clonal rat osteosarcoma cell line. The aminobisphosphonate pamidronate was added to UMR 106-01 cell cultures (10(-8)M to 10(-4)M up to 5 days). The non-aminobisphosphonate clodronate was administered for the same time periods (10(-6)M to 10(-2)M). Cell proliferation, apoptosis and mRNA expression was assessed. Both agents inhibited cell proliferation in a time- and dose-dependent manner. ELISA analysis demonstrated an increase in DNA fragmentation although there was no significant dose-related difference between the doses studied. Bisphosphonate-treated cultures had a greater subpopulation of cells exhibiting morphological changes of apoptosis. Expression of mRNA for osteopontin and RANKL was down-regulated by both agents, while the expression of mRNA for alkaline phosphatase, pro-alpha1(I) collagen and OPG was not altered. Out in vitro work suggests the bisphosphonates not only have direct effects on osteosarcoma cell growth and apoptosis, but also, by altering the relative expression of osteoclast-regulating factors, they may inhibit the activity of osteoclasts and their recruitment.

New Treatment Strategy for Bone Metastases from Breast Cancer

Breast cancer patients frequently develop bone metastasis. Parathyroid hormone-related protein, an osteoclast activating factor, might be necessary for tumorto erode bone and grow at skeletal site. Bisphosphonates have an affinity for bone and are potent inhibitors of osteoclastic bone resorption. In light of this,53 patients with bone metastasis from breast cancer were treated with chemoendocrine(mainly high-dose medroxyprogesterone acetate as the endocrine therapy) therapy + bisphosphonate (pamidronate, Aredia (R)). During the previous 6 years (median 27 months), 53 breast cancer patients with bone metastasis were treated with pamidronate + chemoendocrine therapy. The regimen consisting of pamidronate + chemoendocrine agent was administered to 27 patients as a post relapse first-line regimen and to the remaining 26 cases, which failed first- or second-line treatment as a second or third line regimen. As a result of the combination therapy, sclerotic changes were observed in the osteolytic lesions in 31 of the 53 patients (59%). The effect on the osteolytic lesions did not correlate with the duration of disease free interval, estrogen receptor (ER) status, presence/absence of previous therapy or number of " hot spot(s) ] on bone scintigraphy. Lessening of pain from the bone metastasis was achieved in 83% of the patients after 3 months of pamidronate administration. Pamidronate + chemoendocrine therapy seems highly promising.

Bisphosphonates in the Management of Breast Cancer

BACKGROUND: Bone is the most frequent site of metastasis in patients with breast cancer. Bone metastasis, particularly osteolytic bone destruction, is usually associated with significant morbidity and deterioration of quality of life. Bisphosphonates are specific inhibitors of osteoclast activity used in the treatment of hypercalcemia of malignancy and osteolytic bone disease. METHODS: We reviewed pertinent literature on the use of bisphosphonates therapy to treat metastatic breast cancer. RESULTS: The use of bisphosphonates in the management of osteolytic bone metastases results in improved palliation of symptoms. Use of these agents in the adjuvant setting may help to prevent bone metastases. CONCLUSIONS: Bisphosphonates represent an effective palliative treatment when combined with chemotherapy and hormonal therapy for the management of osteolytic bone metastases. Identifying the exact mechanism of action requires further investigation to better define the possibility of a direct antitumor effect. The role of bisphosphonates in the adjuvant setting is still controversial, pending the results of large randomized trials.

Bisphosphonates in the treatment of malignant bone disease

Tumor-induced osteolysis or lytic bone disease is mediated by osteoclast activation. Osteoclasts can be activated directly by products produced by tumors or indirectly through other nonmalignant cells. By reducing osteoclastic activity, bisphosphonates inhibit bone resorption. Since these agents were shown effective in treating other diseases associated with increased bone resorption, including cancer-related hypercalcemia and Paget's disease of bone, studies have been initiated to explore the use of bisphosphonates in patients with osteolytic bone metastases. Recent large randomized double-blind studies show the efficacy of these agents in reducing skeletal complications in patients with bone metastases from both breast cancer and multiple myeloma.

Pamidronate reduces skeletal morbidity in women with advanced breast cancer and lytic bone lesions: a randomized, placebo-controlled trial. Protocol 18 Aredia Breast Cancer Study Group

PURPOSE

To assess whether pamidronate can reduce the frequency of skeletal morbidity in women with lytic bone metastases from breast cancer treated with hormone therapy.

PATIENTS AND METHODS

Three hundred seventy-two women with breast cancer who had at least one lytic bone lesion and who were receiving hormonal therapy were randomized to receive 90 mg of pamidronate or placebo as a 2-hour intravenous infusion given in double-blind fashion every 4 weeks for 24 cycles. Patients were evaluated for skeletal complications: pathologic fractures, spinal cord compression, irradiation of or surgery on bone, or hypercalcemia. The skeletal morbidity rate (the ratio of the number of skeletal complications to the time on trial) was the primary efficacy variable. Bone pain, use of analgesics, quality of life, performance status, bone tumor response, and biochemical parameters were also evaluated.

RESULTS

One hundred eighty-two patients who received pamidronate and 189 who received placebo were assessable. The skeletal morbidity rate was significantly reduced at 12, 18, and 24 cycles in patients treated with 90 mg of pamidronate (P = .028, .023, and .008, respectively). At 24 cycles, the proportion of patients having had any skeletal complication was 56% in the pamidronate group and 67% in the placebo group (P = .027). The time to the first skeletal complication was longer for patients receiving pamidronate than for those given placebo (P = .049). There was no statistical difference in survival or in objective bone response rate. Pamidronate was well tolerated.

CONCLUSION

Treatment with 90 mg of pamidronate as a 2-hour intravenous infusion every 4 weeks in addition to hormonal therapy significantly reduces skeletal morbidity from osteolytic metastases.

Alendronate blocks metalloproteinase secretion and bone collagen I release by PC-3 ML cells in SCID mice

We have previously shown that alendronate, a potent bisphosphonate compound, can prevent human PC-3 ML tumor cell metastasis to the bone (Stearns and Stearns, 1996, Oncol Res, 8, 69-75). In this paper, tumor cells were injected into the bone medullary cavity of SCID mice femurs both in vivo and following isolation in vitro. ELISAs showed that the amount of collagen I released in the bone marrow (i.e. in in vitro experiments) and the blood plasma (i.e. in in vivo experiments) was a function of the time of incubation or the number of cells injected in the femurs. ELISAs also showed that the levels of matrix metalloproteinase (MMP-2 and MMP-9) secreted in the bone medullary cavity of the femurs directly correlated with the extent of collagen 1 release. In vitro experiments carried out with 'live' and 'devitalized bone' yielded similar results suggesting that the tumor cells (not the osteoclasts) were primarily responsible for the bone solubilization observed. Alendronate pretreatment of the SCID mice (0.1 mg/kg biweekly for 3 weeks) (or the tumor cells) blocked both MMP production by the tumor cells (and the osteoclasts) and collagen I release, providing direct evidence that alendronate might be utilized to prevent bone destruction by metastatic tumor cells. Zymography indicated that MMP-2 activation might be responsible for bone solubilization. In addition, the data suggest that the plasma levels of collagen I might be a marker of bone metastasis and osteolysis.

The role of bisphosphonates for the treatment of bone disease in multiple myeloma

Palliative therapy is often a major objective for clinicians while treating advanced cancer. This is particularly true in multiple myeloma (MM), where bone involvement markedly influences the quality of life of patients. Bisphosphonates (BP) are a new class of drugs regulating bone turnover, which exert their activity mainly by inhibiting osteoclast bone resorption. Three BP (etidronate, ETD; clodronate, CDN; pamidronate, PMD) have so far been investigated in the clinical setting for treating bone disease in patients with MM. The results of these trials, including our own experience, are reviewed here. Although all three BP were effective in lowering hypercalcemia of MM patients, PMD, a second generation BP, clearly had the most substantial long term clinical benefits regarding bony complications, pain and quality of life. CDN also showed some activity in reducing the development of new lytic lesions, while no significant beneficial effect was seen in patients using ETD. Interestingly, some studies have reported an improved survival in subsets of MM patients receiving BP and this is in agreement with recent evidence of possible direct anti-neoplastic activities of these drugs mediated through reduction of IL-6 production and stimulation of neoplastic cell apoptosis.

Alendronate blocks TGF-beta1 stimulated collagen 1 degradation by human prostate PC-3 ML cells

We have previously shown that alendronate can prevent human PC-3 ML tumor cell metastasis to the bone (Wang and Stearns, 1991, Differentiation, 48, 115-25). In this paper, ELISAs and Western blots showed that TGF-beta1 stimulated the secretion of a 72 kDa matrix metalloproteinase 2 (MMP-2) to enhance the solubilization of radiolabeled collagen 1 by metastatic human prostate PC-3 ML cells. A potent bisphosphonate compound, alendronate, inhibited MMP-2 secretion to block solubilization of collagen 1. Alendronate failed to inhibit MMP-2 activity directly, but instead appeared to block cellular secretion of MMP-2. Alendronate failed to inhibit secretion of tissue inhibitor of metalloproteinase-2 (TIMP-2; the inhibitor of MMP-2) and the decrease in collagen 1 solubilization observed may occur, in part, from changes in the molar stoichiometry of TIMP-2 to MMP-2. We conclude that alendronate may be a potent inhibitor of bone resorption based on its ability to block MMP-2 secretion by tumor cells.

Monitoring of multiple myeloma patients by simultaneously measuring marker substances of bone resorption and formation

Fifteen patients (13 males and two females; mean age, 63 years; age range, 46-84 years) with multiple myeloma were studied prospectively (range of follow-up period, 2-6 months) to elucidate the diagnostic validity of biochemical markers of bone formation (bone alkaline phosphatase and the C-terminal propeptide of type I procollagen) and bone resorption (urinary excretion of pyridinium cross-links) for monitoring these patients. Eleven of 15 patients received melphalan i.v. and prednisone p.o. every 4 weeks. All patients were given pamidronate i.v. for inhibition of bone resorption. The mean values of the urinary excretion of pyridinium cross-links were significantly higher in the patients fulfilling the criteria of 'progression' or 'relapse' than in those showing 'response' and those in the 'plateau phase' (P < 0.05). In contrast, neither bone alkaline phosphatase nor C-terminal propeptide serum values differed significantly between these two groups (P > 0.05). The concentrations of both bone formation markers were significantly lower in the patients than in the samples obtained from apparently healthy persons (P < 0.001). There was a significant inverse correlation between the number of pamidronate courses and the serum concentrations of bone alkaline phosphatase (P < 0.05). A lack of correlation was observed between the urinary excretion of pyridinium cross-links and all other laboratory parameters measured (serum concentrations of total protein, calcium, creatinine and (beta 2-microglobulin). In conclusion, the urinary excretion of pyridinium cross-links might be a useful parameter for monitoring multiple myeloma patients. Decreased values of bone formation markers may be due to a suppressive effect of the bisphosphonate agents administered or reflect the severity of osteolytic lesions which have been described as being associated with unbalanced bone remodelling.

A New Endocrine Therapy Strategy for Bone Metastasis of Breast Cancer: The Effect of Biological Response Modifiers and 22-Oxacarcitriol on Animal Models

To consider the treatment order of hormonal agents is very important in order to achieve a higher quality of life (QOL) and better survival rates in breast cancer patients with bone metastasis. Tamoxifen (TAM) or a luteinizing hormone-releasing hormone (LH-RH )analogue is the first-line, an LH-RH analogue (or TAM) the second-line, and medroxyprogesterone acetate(MPA) the third-line treatment in premenopausal patients with breast cancer. In postmenopausal patients, TAM (or toremifene) is the first-line, an aromatase inhibitor the second-line, and MPA the third-line treatment. In experimental studies using female Sprague-Dawley rats with 7, 12-dimethylbenz ma]anthracene (DMBA)-induced mammary carcinoma, biological response modifiers (BRM)(Krestin, Picibanil) and a vitamin D3 analogue, 22-oxacarcitriol (OCT)augmented the antitumor effect of hormonal agents. A combination of hormonal agents and BRM or OCT may be the endocrine therapy of choice for bone metastasis of breast cancer.

Pathogenesis and management of bone lesions in multiple myeloma

Osteolytic lesions are among the hallmarks of multiple myeloma (MM). On the other hand, they are rare in B cell malignancies other than MM. Data have shown a close relationship between myeloma cell growth factors and factors involved in the occurrence of bone lesions in MM. Biophosphonates, which are potent inhibitors of bone resorption to control MM-induced hypercalcemia, are of interest due to their ability to slow the progression of MM bone disease.

Effects of oral clodronate on bone mineral density in patients with relapsing breast cancer

The high prevalence of bone metastases in breast cancer and the risk that spinal and femoral osteoporosis may add further morbidity provide a rationale for bisphosphonate therapy in patients with skeletal metastases from mammary carcinoma. We investigated the effects of oral clodronate given during 9 months, with a 24-month follow-up, on bone mineral density (BMD), on biochemical markers of bone remodeling, and on osseous complications in 67 women with documented relapsing breast cancer, aged 58.7 +/- 1.5 years (x +/- SEM). Patients with active cancer disease were randomly allocated to two groups, with or without clodronate treatment (1600 mg/day, orally). Twenty-six women considered in complete remission (52.4 +/- 2.4 years) were also studied. Expressed in deviation from gender- and age-matched normals (z score), base-line BMD at the levels of lumbar spine (LS), femoral neck (FN), and midfemoral shaft (FS) was +0.10 +/- 0.22 vs. -0.12 +/- 0.25, +0.03 +/- 0.19 vs. -0.54 +/- 0.24, and +0.08 +/- 0.14 vs. -0.02 +/- 0.22, in patients with active breast cancer and in subjects in remission, respectively. After 9 months of treatment, fasting urinary calcium to creatinine ratio was lower (0.26 +/- 0.04 vs. 0.40 +/- 0.04 mmol/mmol creatinine, p < 0.02) and serum osteocalcin was stabilized (-2.1 +/- 1.1 vs. +7.0 +/- 3.3 micrograms/L, as compared with pretreatment values, p < 0.02), in the clodronate-treated group. The rate of osseous complications (pathological fracture, hypercalcemic episode, scintigraphic or radiological evidence of metastasis development, chemo- or radiotherapy for bone disease progression) was 28.8 events per 100 patient-year in the clodronate-treated group vs. 39.0 in controls, and 31.5 vs. 40.5, after 9 and 15 months of follow-up, respectively. In 15 women without evident LS bone metastasis (7 clodronate-treated and 8 controls), LS BMD increased in the clodronate-treated group by +5.2 +/- 2.5% vs. -0.3 +/- 1.4%, and +8.1 +/- 4.7 vs. -0.9 +/- 1.7, after 10.3 +/- 0.4 and 17.3 +/- 1.2 months, respectively (p < 0.01), as compared with pretreatment values. These results indicate that clodronate treatment decreased bone turnover and attenuated cancer-related bone morbidity. In addition, clodronate increased LS BMD in apparently unaffected bone of women with relapsing breast cancer.

Metabolic effects of pamidronate in patients with metastatic bone disease

We have evaluated the value of specific bone resorption markers in monitoring metastatic bone disease to define the duration of action of a single high-dose pamidronate infusion. Twenty patients received a single infusion of pamidronate 120 mg for painful bone metastases. Ten out of these 20 patients also received a second infusion. They were evaluated at baseline, 2, 4 and 8 weeks after each infusion. A composite pain questionnaire, serum and urine tests were carried out at these time points. Bone resorption markers measured included urinary calcium, hydroxyproline and two new markers: pyridinoline and deoxypyridinoline. Reference values were defined by 20 healthy controls matched by age and sex. Pamidronate induced a profound fall in bone resorption with a maximal effect within the first month after therapy. Changes in urinary calcium levels were confounded by a rise of 100% in the parathyroid hormone levels. Before treatment, pyridinoline and deoxypyridinoline were increased in 70% of patients, while urinary calcium was increased in only 40% of them. Thirteen patients had a > or = 50% fall in deoxypyridinoline levels and were considered as biochemical responders. These patients had a mean reduction in pain score of about 30% of baseline levels, which was significantly higher than the seven non-biochemical responders. In conclusion, urinary calcium is not a precise marker of bone resorption. Deoxypyridinoline seems to be the most specific bone resorption marker in cancer patients. Biochemical responders have the most benefit from pamidronate in terms of pain relief. This suggests that patients may benefit from more potent or repeated infusions of bisphosphonates.

The role of bisphosphonates in the treatment of bone metastases--the U.S. experience

Frequent complications of bone metastases include pain, pathologic fracture, hypercalcemia and spinal cord compression. Lytic bone metastases result from excessive activation of osteoclasts by tumor-produced cytokines. Aredia (pamidronate) is a potent bisphosphonate that inhibits osteoclast activation. In two dose-seeking phase I trials in patients with breast cancer and prostate cancer, repeated intravenous infusion of Aredia was shown to be safe and effective in reducing bone resorption and pain. In a randomized phase III trial of 377 patients with multiple myeloma, Aredia was administered in a dosage of 90 mg i.v. every 4 weeks. Compared with placebo, treatment with Aredia was associated with a significant decrease in bone pain and in the incidence and time to development of all skeleton-related events. Data from two phase III breast cancer trials each involving 300 patients are now being analyzed. The newer bisphosphonates can safely be used together with standard anticancer therapy to provide effective palliation of symptoms caused by lytic bone metastases.

Causes and treatment of bone pain of malignant origin

Pain relief has been one of the oldest and most important duties of the physician. There has been little change with regard to this obligation of all caregivers. One-third of patients with advanced cancer will develop clinically relevant skeletal metastases and chronic pain during the course of their disease. All physicians involved in the treatment of cancer patients should know the basic principles of pain treatment. These are described in the following article with special regard to bone pain of malignant origin. Correct assessment of pain intensity and frequency, as well as of the probable causes of pain, and the administration of adequate analgesic treatment should achieve satisfactory results in the vast majority of patients. Every physician should obtain detailed knowledge of the indications and adequate administration of pain-killing therapy as well as possible adverse effects and their successful treatment. It is important in particular to concentrate on a few nonsteroidal anti-inflammatory drugs (NSAIDs) as well as opiates. Knowledge of adequate doses, maximal recommended daily doses, pharmacological properties, important adverse effects and interactions is essential for success in the daily routine. Only by selecting 2 or 3 drugs from each step in the analgesic ladder (WHO) will the nonspecialised physician obtain sufficient experience for optimal analgesia. Physicians should also not hesitate to contact other specialists (medical oncologists, radiotherapists, neurosurgeons, anaesthesiologists and others) in order to maximise benefit for an individual patient.

Efficacy of pamidronate in reducing skeletal events in patients with advanced multiple myeloma. Myeloma Aredia Study Group

BACKGROUND

Skeletal complications are a major clinical manifestation of multiple myeloma. These complications are caused by soluble factors that stimulate osteoclasts to resorb bone. Bisphosphonates such as pamidronate inhibit osteoclastic activity and reduce bone resorption.

METHODS

Patients with stage III multiple myeloma and at least one lytic lesion received either placebo or pamidronate (90 mg) as a four-hour intravenous infusion given every four weeks for nine cycles in addition to antimyeloma therapy. The patients were stratified according to whether they were receiving first-line (stratum 1) or second-line (stratum 2) antimyeloma chemotherapy at entry into the study. Skeletal events (pathologic fracture, irradiation of or surgery on bone, and spinal cord compression), hypercalcemia (symptoms or a serum calcium concentration > or = 12 mg per deciliter [3.0 mmol per liter]), bone pain, analgesic-drug use, performance status, and quality of life were assessed monthly.

RESULTS

Among 392 treated patients, the efficacy of treatment could be evaluated in 196 who received pamidronate and 181 who received placebo. The proportion of patients who had any skeletal events was significantly lower in the pamidronate group (24 percent) than in the placebo group (41 percent, P < 0.001), and the reduction was evident in both stratum 1 (P = 0.04) and stratum 2 (P = 0.004). The patients who received pamidronate had significant decreases in bone pain and no deterioration in performance status and quality of life. Pamidronate was tolerated well.

CONCLUSIONS

Monthly infusions of pamidronate provide significant protection against skeletal complications and improve the quality of life of patients with stage III multiple myeloma.

Analgesic effect of bisphosphonates on bone pain in breast cancer patients: a review article

Bisphosphonates exert their analgesic effect by several mechanisms. The long-term effects are probably due to osteoclast inhibition. The acute pain-relieving effect, which occurs within days or a week, is likely to be associated with the reduction of various potentially pain-producing substances. As regards pamidronate, several open, controlled studies have shown a significant effect on bone pain in 30-70% of breast cancer patients. The effects have been dose-dependent: a mean dose of 15 mg i.v./week is obviously suboptimal, whereas higher doses yield markedly better effects. The dose response is most evident at doses between 15 and 30 mg/week. Furthermore, the total dose per infusion is of interest: 30 mg every 2 weeks is an ineffective treatment, whereas 60 mg every 4 weeks is more effective. Thus, both the dose per week and the total dose per infusion are of importance in order to achieve optimal treatment. Patients with rapid progression of their disease require higher doses than patients with slow progression. Parenteral therapy is more effective than oral treatment. Both oral and parenteral clodronate exert a significant, positive effect on total skeletal morbidity and thus probably also on bone pain. Unfortunately, pain measurements have not been performed and evidence for pain reduction is indirect. Specific pain studies and studies of quality of life, with few exceptions, are, however, still lacking.

Pamidronate in patients with painful bone metastases, who failed initial treatment with hormones and/or chemotherapy

In an open prospective study. 40 patients with progressing painful bone metastases received 45 mg pamidronate by 1-h infusion every 3 weeks. A total of 27 patients (67%; 95% CI 53%-81%) experienced relief of pain as shown by the significant reduction of the bone pain score after three pamidronate administrations (from 2.25 +/- 0.64 to 1.15 +/- 0.36). Furthermore, 20 patients (60%) reduced their consumption of analgesics. We did not observe any objective response by skeletal radiological examination. In 11 patients presenting a skeletal progressive disease, bone pain improved, as well as their mobility score, but not their fatigue score. Treatment was well tolerated. Only 1 patient discontinued the treatment because of fever and cutaneous rash after the first administration. In conclusion, our results seem to confirm that pamidronate exerts a benefical effect on bone pain and mobility impairment in patients with painful osteolytic bone metastases.

Opioid pharmacotherapy in the management of cancer pain: a survey of strategies used by pain physicians for the selection of analgesic drugs and routes of administration

BACKGROUND

This survey documents the strategies used by pain control physicians in the selection of opioid drugs and routes of administration in the management of inpatients referred to a cancer pain service.

METHODS

The following approaches were prospectively evaluated during the treatment of 100 consecutive inpatients: 1) the influence of the evaluation of the goals of care on decision making, 2) selection of opioid drugs, 3) indications for changing opioid drugs and the frequency with which this strategy is used, and 4) selection of route of administration.

RESULTS

Eighty of the 100 patients underwent a total of 182 changes in drug, route, or both drug and route before discharge or death. The major reasons for change were to improve the convenience of treatment regimen in the setting of adequate pain relief (31.4%), diminish side effects in the setting of controlled pain (25.0%), reduce the invasiveness of therapy in the setting of controlled pain (19.3%), and simultaneously improve pain control and reduce opioid toxicity (17.7%). When opioid toxicity was the reason for change, physicians changed the opioid drug in 71% of cases and the route in 29%. When convenience or invasiveness were targeted, the physicians changed the route in 61% of cases and the opioid in 39%. Forty-four patients required one or more change in the opioid, and 20 required 2 or more changes (range, 2-6 changes). At the time of discharge (n = 82), morphine was more commonly selected than hydromorphone or fentanyl (39% vs. 23% vs. 17%) and the routes of administration were oral (57%), transdermal (18%), intravenous (18%), subcutaneous (5%), and intraspinal (4%). Therapeutic changes were associated with improvement in physician-recorded pain intensity and a lower prevalence of cognitive impairment, hallucinations, nausea and vomiting, and myoclonus among patients who were discharged from the hospital.

CONCLUSIONS

These data illustrate the application of strategies for selections of opioid drugs and their route of administration that are recommended in current guidelines for the management of cancer pain.

Intravenous pamidronate disodium treatment of bone metastases in patients with breast cancer. A dose-seeking study

BACKGROUND

Treatment of the symptoms of bone metastases currently involves the use of narcotic medication, radiation therapy, or hormonal therapy. Pamidronate disodium, a bisphosphonate, may prove helpful in the palliative treatment of bone metastases in patients with breast cancer as demonstrated in this multicenter, dose-ranging trial.

METHODS

Ambulatory female patients age 18 years or older with breast cancer metastatic to bone and a life expectancy of at least 3 months were eligible for the study. Bone metastases were confirmed by bone scan or bone survey within 6 months of enrollment. Sixty-one patients were treated as outpatients and were randomized to receive one of four intravenous pamidronate regimens for 12 weeks: 30 mg administered every 2 weeks, 60 mg every 4 weeks, 60 mg every 2 weeks, or 90 mg every 4 weeks. The primary efficacy parameter for this study was pain score. The change from baseline in pain score was determined for each patient at each study visit and at endpoint, defined as the last postbaseline evaluation for each patient before or at week 12. Secondary efficacy variables included narcotic scores, urinary calcium/creatinine and hydroxyproline/creatinine ratios, serum osteocalcin and bone alkaline phosphatase concentrations, and bone lesion (radiologic) response.

RESULTS

At 3 months, the regimens of 60 mg every 4 weeks, 60 mg every 2 weeks, and 90 mg every 4 weeks resulted in significant reduction in bone pain beginning by week 6 of treatment. The regimen of 30 mg every 2 weeks was not effective. Narcotic use, as reflected by narcotic scores, did not parallel the pain scores, because there was little evidence of any effect for any of the treatment groups. Reduction in bone pain was accompanied by decreases in urinary calcium/creatinine and hydroxyproline/creatinine ratios, and bone alkaline phosphatase concentrations. Side effects of pamidronate were mild and transient. Radiographic changes consistent with healing of lytic lesions were observed in 15 patients (25%).

CONCLUSION

Intravenous pamidronate is a well tolerated treatment that produced significant relief of bone pain in the majority of patients with metastatic breast cancer at the three highest doses tested.

Palliative care

Though many of the treatment strategies used in palliative care have never been subjected to clinical trial, it has been argued that advances in palliative care have outstripped those in many other specialties. This article is not a comprehensive review of therapeutic options, nor even of recent advances in this topic, but concentrates on the latest developments and controversies in the pharmacological treatment of four frequent and important symptoms: neuropathic pain, anorexia and cachexia, intestinal obstruction, and breathlessness. It is difficult to perform blinded, randomised trials in patients with advanced disease and poor performance status, yet it is these patients who may gain most from the adoption of new well evaluated treatment strategies.

Effect of the bisphosphonate risedronate on bone metastases in a rat mammary adenocarcinoma model system

Risedronate (NE-58095) is a third-generation bisphosphonate with very potent antiresorptive activity but few toxic effects. The purpose of this work was to evaluate the effect of risedronate treatment on bone metastases produced in a rat breast cancer model. Berlin Druckrey IV rats inoculated with ENU1564 mammary adenocarcinoma cells were treated daily with risedronate or a saline placebo. Survival times, dictated by extraskeletal metastases (lung, heart, and brain), were not affected by risedronate treatment. Risedronate-treated animals had skeletal changes associated with decreased remodeling of bones undergoing endochondral ossification, most prominently affecting the appendicular skeleton. Despite the skeletal alterations induced by the treatment, the distribution of bone metastases throughout the surveyed skeletal sites was similar for treated and untreated animals. Bone metastases were enumerated in histologic sections of distal femur, spine, and skull. Tumor size was estimated from area measurements obtained from histologic lesions in distal femoral metaphyses and vertebral bodies. A greater number of treated rats had no bone metastases in any of the examined sections (30 versus 16.1% of untreated rats). Multiple bone metastases were observed less frequently in treated rats (33.3 versus 71% of untreated rats). Treated rats had fewer observed bone metastases in each examined site than untreated rats (p < or = 0.025). Mean tumor areas in femora and vertebrae were smaller in treated rats (p < or = 0.05), due to the less frequent presence of very large lesions. In untreated animals, osteoclasts appeared to be active at the tumor/bone interface and osseous structures were often completely replaced by expanding tumors. In contrast, metastases in treated animals caused less disruption of skeletal histoarchitecture. The apparent lack of osteoclastic activity and retention of bone within lesions suggested a decreased contribution of osteoclasts to the bone resorptive process. An in vivo immunohistochemical cell proliferation assay failed to reveal differences in the percentage of dividing tumor cells in bone metastatic sites in treated versus untreated animals. The results demonstrate significant effects of risedronate treatment on the incidence and size of observed skeletal metastases in this model.

Cancer pain management. Current strategy

Pain is among the most prevalent symptoms experienced by cancer patients. A strategy for the management of cancer pain is now widely accepted, and when well implemented, is usually effective. Unfortunately, many oncologists are ill-prepared for the task of pain assessment and management, and the outcomes achieved in clinical practice are often suboptimal. The various elements in the pain management strategy are described. Patient assessment, the use of primary therapies and systemically administered nonopioid and opioid analgesics are pivotal to the strategy. Practical aspects of opioid pharmacotherapy encompass drug selection and dosing considerations including selection of an appropriate route of administration, dose titration, and the management of side effects. Specific approaches are described for the treatment of patients for whom an acceptable balance between relief and side effects of opioids is not achieved. These comprise noninvasive interventions, including the use of adjuvant analgesics, psychological therapies, and physiatric techniques, and invasive interventions, such as the use of intraspinal opioids, neural blockade, and neuroablative techniques. Finally, the use of sedation in the treatment of patients with pain that is refractory to other interventions is addressed. The skilled application of this strategy can provide adequate relief to the vast majority of patients, most of whom will respond to systemic pharmacotherapy alone. Patients with refractory pain should see specialists in pain management or palliative medicine who can address these difficult problems.

New bisphosphonates in the treatment of bone metastases

Normal skeletal integrity is maintained by physiological bone turnover through a coupled process of bone resorption, mediated by osteoclasts, followed by new bone formation, mediated by osteoblasts. Major features of the pathogenesis of cancer-associated skeletal destruction are enhanced osteoclast-mediated bone resorption and disruption of normal bone formation. In this article, the literature on the pathogenesis and clinical manifestations of metastatic bone disease is discussed. Animal and clinical trials investigating novel bone targeted agents, emphasizing the bisphosphonates, are critically assessed. The most frequent clinical manifestations of bone metastases are pain, fracture, immobility, spinal cord compression, and hypercalcemia. New treatments under study for patients with bone metastases include agents specifically targeted to the skeleton such as bone-seeking radioisotopes and bisphosphonates. Studies in animal models of metastatic bone disease show that these bisphosphonates are able to inhibit tumor-induced osteolysis and are potentially useful in this condition. Bisphosphonates have been investigated in several clinical trials of patients with skeletal metastases from breast cancer, prostate cancer, and multiple myeloma. Overall, the studies investigating bone targeted radioisotopes or bisphosphonates for the treatment of morbidity due to skeletal metastases have been inconclusive. An improved understanding of the pathogenesis of metastatic bone disease and preclinical studies with bisphosphonates suggest that these agents may have a role in the treatment of this disorder. Additional trials of new generation bisphosphonates, employing a rigorously controlled, randomized study design with adequate numbers of subjects, are needed to demonstrate the safety and efficacy of this class of agents in this setting.

Disodium Pamidronate in the Treatment of Bone Metastases from Breast Cancer

Aims and Background

Symptomatic relief of bone metastases with biphosphonates has been previously reported, but limited data are available on the possibility of the induction of sclerosis in osteolytic lesions.

Methods

We therefore initiated an open study with disodium pamidronate (45 mg infused over 1 h and repeated every 21 days) in patients with bone metastases from breast cancer pretreated with chemotherapy and/or hormonetherapy. Fourteen patients wiht measurable lytic or mixed bone disease entereted the study. No other systemic therapy for breast cancer was allowed after their Inclusion in the study.

Results

No radiologic evidence of bone sclerosis of lytic disease was seen. After 2 months of therapy, 9 patients had progressed and 5 had stable disease. The median time to progression of bone disease was 1.6 months (range, 1-9). No significant improvement in terms of symptomatic status or analgesic consumption was recorded. The treatment was well tolerated, and no significant local or systemic toxicity was observed.

Conclusions

Disodium pamidronate at a dose of 45 mg every 3 weeks is not capable of inducing sclerosis of lytic lesions from pretreated breast cancer. Further trials concentrating on higher dosages of disodium pamidronate are warranted.

Effective treatment of malignant hypercalcaemia with a single intravenous infusion of clodronate

Thirty patients with hypercalcaemia due to malignancy that persisted following rehydration, were treated with a single dose of the bisphosphonate, clodronate. Clodronate (1.5 g) was administered intravenously in 500 ml normal saline over 4 h. Serum and urine biochemistry were measured before and after treatment and the results were compared with data from 15 patients given the recommended regimen 300 mg intravenous clodronate daily for 5 consecutive days. The single infusion induced a rapid and significant fall in serum calcium, apparent at day 3 (P < 0.0001) that persisted to the end of follow-up at day 10 (P < 0.001). Eighty per cent (24/30) of patients became normocalcaemic. The response was associated with a significant decrease in fasting urinary calcium excretion, and no change in renal function, as judged by serum creatinine. The same dose of clodronate, given as 5 daily infusions, induced a comparable decrease in serum calcium, but was less rapid in onset so that at day 3 the serum calcium was significantly lower with the single infusion (P = 0.02). The calcium lowering effect of both regimens depended on the tumour type. We conclude that the single infusion of 1500 mg clodronate is as effective in reducing serum calcium as the same dose given over 5 days. The single infusion has a more rapid onset of effect, is more convenient than multiple infusions, and has no adverse effect on renal function.

Medical treatment of tumor-induced hypercalcemia and tumor-induced osteolysis: challenges for future research

Tumor-induced hypercalcemia (TIH) and tumor-induced osteolysis (TIO) are essentially due to a marked increase in osteoclast-mediated bone resorption. Parathyroid-hormone-like protein plays an essential role in TIH, and maybe in TIO, but other substances, such as growth factors or cytokines, could contribute to the osteoclast activation and osteoblast inhibition secondary to the neoplastic infiltration of the skeleton. Treatment of TIH essentially consists of volume repletion and administration of potent anti-osteolytic drugs. Intravenous administration of the bisphosphonate clodronate or pamidronate is particularly useful for this. Pamidronate at a dose of 1.0-1.5 mg/kg as a single 4- to 24-h infusion can normalize serum calcium in about 90% of hypercalcemic cancer patients. The apparently low response rate of bone metastases to systemic antineoplastic therapy seems essentially to reflect the relative insensitivity of our current methods for assessing response in TIO. Quantitative evaluation of pain and of newly developed biochemical markers of bone turnover could be particularly useful for early assessment of response. Prolonged administration of oral pamidronate could reduce by almost one-half the complications of TIO, and iterative bisphosphonate infusions could induce a dramatic relief of bone pain in one-third and a sclerosis of lytic lesions in one-fourth of the cases. These data must, however, be confirmed in randomized blind trials and many questions remain unanswered concerning the optimal therapeutic schemes. Despite these limitations, medical therapy of TIO by non-cytotoxic means has already become a reality.

Modulation of tumour-induced bone resorption by bisphosphonates

Tumour cells produce systemic or local factors which can stimulate osteoclast development and activity leading to increased bone resorption. The clinical consequences are bone pain, fractures and hypercalcaemia. Inhibitors of osteoclast-mediated bone resorption, such as the bisphosphonates, are now the treatment of choice for tumour-induced hypercalcaemia. Recent evidence indicates that these compounds, especially the newer ones, reduce skeletal morbidity in patients with metastatic bone disease and improve their quality of life. Better understanding of the mechanisms underlying tumour-induced bone resorption and development of more potent and less toxic bisphosphonates will lead to improved management of patients with malignant diseases involving the skeleton.

[Osteolytic metastases of breast cancer and biphosphonates]

Three-quarters of breast carcinomas at an advanced stage display metastases, usually of the osteolytic type. Osteolysis results from a predominant increase of osteoclastic activity stimulated by humoral or local factors secreted by cancerous cells. Bisphosphonates interfere with osteoclasts and therefore can reduce the osteolysis. These compounds act through three main mechanisms: physico-chemical inhibition of bone crystal, cytostatic effect on osteoclasts, and in the case of pamidronate, direct or indirect action on the mononucleate precursors of osteoclasts. Three bisphosphonates are now available: etidronate, clodronate and pamidronate. Ten published studies report on their use in breast carcinoma with osteolytic metastases, and without hypercalceamia. Four studies concern clodronate in 54 patients, and six studies concern pamidronate in 128 patients. Intravenous pamidronate seems to be the more effective of the two, with densification of the lytic areas in 25% of the cases. All studies mention a decrease of pain, risk of fracture, hypercalcaemia and new metastatic locations. Side-effects are minimal. Controlled studies are needed to confirm the position of bisphosphonates in the management of malignant osteolysis.

Radiopharmaceuticals for palliation of metastatic osseous lesions: biologic and physical background

The intimate admixing of bone matrix and bone marrow is a central point in devising therapy of metastatic lesions. Since specific modalities are not yet available for destroying the malignant cells, treatment is usually palliative. The use of stable gallium (Ga-nitrate) and of a diphosphonate (aminohydroxypropylidine diphosphonate disodium) as osteoclast inhibitors is discussed. The marrow, as well as the matrix, can be affected by external radiation. This is also true with bone-seeking radiopharmaceuticals. There is no ideal radiopharmaceutical available for treating metastases in bone, but the characteristics of several presently available (or proposed) are discussed, and possible use of tumor radiation sensitizers or bone marrow protectors is mentioned. Difficulties are also encountered in calculating accurate dosimetry. Clinical experience is needed to determine a reasonable optimal dose with any particular radiopharmaceutical for relief of pain with low bone marrow toxicity.