Somatostatin analogue treatment for malignant hypercalcaemia

What Lies behind Paraneoplastic Hypercalcemia Secondary to Well-Differentiated Neuroendocrine Neoplasms? A Systematic Review of the Literature

BACKGROUND

Neuroendocrine neoplasms (NEN) originate from neuroendocrine cells ubiquitously spread throughout the body. Hypercalcemia associated with cancer is the most common life-threatening metabolic disorder in patients with advanced stage cancer. Paraneoplastic hypercalcemia is more commonly associated with hematological malignancies, renal and breast carcinomas, and squamous cell carcinomas, but it has also been described in patients with well-differentiated NEN, where it often remains undiagnosed. Among its causes, systemic secretion of parathyroid hormone-related protein (PTHrP) and ectopic production of 1,25-dihydroxyvitamin D and parathyroid hormone (PTH) may be considered paraneoplastic causes of hypercalcemia. In order to clarify the diagnostic work up of paraneoplastic hypercalcemia in patients with NEN, we perform a systematic review, which is lacking in the literature.

METHODS

We performed a data search using MEDLINE and SCOPUS including papers from 1961 to 2021. We selected articles on paraneoplastic hypercalcemia associated with well-differentiated NEN.

RESULTS

The search led to the selection of 78 publications for a total of 114 patients. Pooled data showed that the most frequent primary tumor site associated with paraneoplastic hypercalcemia was pancreatic NEN, followed by Pheochromocytoma. In most cases, paraneoplastic hypercalcemia was caused by PTHrP production and secretion. In more than two thirds of cases, paraneoplastic hypercalcemia was present at the time of NEN diagnosis and, in metachronous cases, was related to local recurrence, distant metastasis development, or tumor progression. In most patients, a combination of therapeutic approaches was employed, and reduction of the tumor burden was essential to control the paraneoplastic syndrome.

DISCUSSION

The onset of hypercalcemia associated with cancer in patients with well-differentiated NEN represents a major clinical challenge. The complex clinical and therapeutical management of paraneoplastic hypercalcemia implies the need for a multidisciplinary approach, aimed at controlling the clinical syndrome and tumor growth.

The role of octreotide in symptom management in oncology and palliative care

Objective. To provide an overview of the role of octreotide for managing symptoms in oncology and palliative care.

Data Sources. A search of MEDLINE and IDIS databases from 1985 to 1999 and CANCERLIT from 1993 to 1999 was conducted using the terms octreotide, cancer and palliative care. The reference lists from selected articles were also reviewed. Clinical trial databases on the Internet were searched. Oncology and palliative care textbooks were also used to obtain additional references.

Data Extraction. The retrieved literature was reviewed to discuss the pharmacology, pharmacokinetics, adverse effects, indications and principally, the clinical use of octreotide for controlling a number of symptoms encountered in the oncology and palliative care population.

Data Synthesis. The unique inhibitory activity of octreotide lends itself to many possible indications, including diarrhoea from a number of causes, bowel obstruction, nausea and vomiting, bleeding, death rattle, gastrointestinal fistulae, pain and hypercalcaemia. However, convincing pieces of evidence from large prospective clinical trials are required to realise its full potential in oncology and palliative care. Completed studies and clinical experience suggest that octreotide has a role in the treatment of a number of difficult-to-manage conditions, particularly bowel obstruction and diarrhoea due to disease or treatment-related causes. Proposed benefits of octreotide must be weighed against the possible adverse effects and cost effectiveness of treatment.

Bisphosphonate-associated osteomyelitis of the jaw: guidelines for practicing clinicians

OBJECTIVE

To evaluate the literature and discuss the risk factors, mechanisms, pathophysiologic aspects, and recommended management of bisphosphonate-associated osteomyelitis of the jaw (BAOMJ).

METHODS

More than 350 published articles, case reports mentioning BAOMJ, and independent histology slides from BAOMJ lesions were reviewed critically. The most pertinent publications are cited and discussed.

RESULTS

The incidence of BAOMJ increases after extraction of teeth, dentoalveolar surgical procedures, or recent oral trauma leading to exposed maxillary or mandibular bone. Contributory factors include poor oral hygiene, oral infections, periodontal disease; recent or ongoing corticosteroid administration or chemotherapy; compromised immune status; diabetes or vascular insufficiency; old age; chronic diseases; and malignancies. On average, 1 of every 100,000 patients treated with bisphosphonates orally for osteoporosis or Paget disease of bone may develop BAOMJ-like lesions. Patients with cancer often receive bisphosphonate doses 10 times or higher, and also more frequently, than those used in patients with osteoporosis or Paget disease of bone. Therefore, greater frequency of administration of bisphosphonates, higher dosages, and prolonged use (that is, for more than 2 years) are likely to be factors triggering BAOMJ.

CONCLUSION

The association of bisphosphonate therapy with BAOMJ is rare in noncancer patients and is likely to be a class effect that may occur with use of any bisphosphonate. Whether patients with cancer require such a high frequency of intravenously administered bisphosphonates needs to be investigated. Following established guidelines can decrease the risks of BAOMJ in vulnerable patients. Rather than necrotic bone, current evidence supports an infectious and perhaps immunologic underlying cause for BAOMJ. The estimated incidence of BAOMJ among noncancer patients receiving bisphosphonates is about 0.001%, whereas among patients with cancer receiving intravenous bisphosphonate therapy the incidence is between 0.5% and 4%, depending on the dose, frequency, and duration of therapy (on average, approximately 2%). Nevertheless, the benefits of bisphosphonates far outweigh the risks.

Somatostatin receptor expression in a parathyroid hormone-related peptide-secreting pancreatic neuroendocrine tumour causing severe hypercalcaemia

BACKGROUND

Humoral hypercalcaemia is a common complication of malignancy with parathyroid hormone-related protein (PTHrP) as a major cause. Breast and lung cancer are relatively common sources of ectopic PTHrP secretion leading to increased osteoclastic bone resorption.

CASE REPORT

We report the rare case of a 40-year-old man with severe hypercalcaemia due to a PTHrP-secreting poorly differentiated endocrine carcinoma of the pancreas. On immunohistochemistry, the tumour was positive for PTHrP and somatostatin receptors sst1, sst2, and sst3, whereas sst4 and sst5 were not detected. We demonstrate the transient improvement of hypercalcaemia after adding octreotide to the treatment mainstays in hypercalcaemia of malignancy (fluid repletion, administration of bisphosphonates, loop diuretics, and glucocorticoids).

CONCLUSION

To the best of our knowledge, this is the first report showing somatostatin receptor expression in a PTHrP-secreting pancreatic neuroendocrine tumour.

Systematic review of bisphosphonates for hypercalcaemia of malignancy

BACKGROUND

Bisphosphonates are the treatment of choice for hypercalcaemia of malignancy (HCM) but there is no consensus regarding which drug or dose should be given. We designed a systematic review to investigate the efficacy of bisphosphonates in the treatment of HCM.

METHODS

We identified randomized controlled trials (RCTs) by searching electronic databases, scanning of reference lists, and consultation with experts and pharmaceutical companies. Foreign papers were translated. Inclusion criteria were RCTs, confirmed malignant disease and measurement of serum calcium (ionized or corrected for albumin) postrehydration. The primary outcome was number of patients achieving normocalcaemia. Secondary outcomes were time to normocalcaemia, time to relapse and toxicity.

RESULTS

Twenty-seven papers and two abstracts, using intravenous bisphosphonates, fulfilled the inclusion criteria. Data from 26 studies were used in analyses. Due to the heterogeneity of studies, meta-analysis could not be performed. Pamidronate was more effective than placebo, mithramycin, etidronate (7.5 mg/kg) and low-dose clodronate (600 mg), but equal to higher dose clodronate (1500 mg). Clodronate and etidronate were superior to placebo; incadronate was superior to elcatonin; gallium nitrate was superior to etidronate. No difference was seen between alendronate and clodronate. Three dose finding studies showed no difference between 30-90 mg of pamidronate, but one well designed study showed increasing efficacy with increasing dose. Studies using increasing doses of ibandronate (0.6-4 mg), alendronate (2.5-15 mg), and incadronate (2.5-10mg), showed a dose response. Duration of administration of pamidronate did not affect efficacy (six studies).

CONCLUSION

Bisphosphonates normalize calcium in >70% patients with minimal side effects. Aminobisphosphonates are most effective at maintaining normocalcaemia and should be given in high dose irrespective of baseline serum calcium.

The clinical role of somatostatin analogues as antineoplastic agents: much ado about nothing?

BACKGROUND

Somatostatin (SST) analogues represent a novel approach for the treatment of certain cancers. The objective of this article is to summarise the current knowledge on SST analogues in the treatment of cancer patients.

METHODS

Computerised (Medline) and manual searches were performed to identify publications on clinical trials published in the English-speaking literature between 1966 and 2000. Information abstracted included patients' pre-treatment status, histology, SST receptor (SSTR) evaluation, type of SST analogue, application schedule and dose, duration of treatment, side-effects, response criteria applied (i.e. WHO response criteria, biochemical criteria or symptomatic investigations) and survival.

RESULTS

Our search disclosed 22 case reports, five phase 1 and 47 phase II trials, and eight randomised clinical trials using SST analogues (octreotide, lanreotide and vapreotide) as antineoplastic agents. With regard to the phase II trials, conflicting results have been demonstrated in almost all tumour entities investigated. The few randomised studies published so far have shown an impact on survival in patients with hepatocellular cancer, while the effect attributed to treatment in patients with gastrointestinal adenocarcinomas might well have been due to an exceptionally short survival in the control group. There appears to be evidence that SST analogues are able to enhance the therapeutic effects of hormonal intervention in patients with breast cancer, prostate cancer and probably pancreatic cancer. Interpretation of the findings, however, is complicated by the fact that patients were heavily pre-treated in some studies and response criteria have not been uniformly applied. In addition, most studies have not been designed to distinguish between receptor-mediated (direct) and indirect effects of SST analogues in tumour patients.

CONCLUSIONS

According to the results obtained so far, there can be no doubt about the wide therapeutic index and the high efficacy of SST analogues in the symptomatic management of neuroendocrine tumours. Apart from these indications, the data do not justify recommendation of SST analogues as antineoplastic agents outside of clinical trials, as the optimal dose and schedule of application for antineoplastic activity has not been defined for currently used agents. Carefully designed clinical trials including investigation of SSTR status before treatment, evaluation of an indirect mechanism of SST analogues, and assessment of optimal combination of hormone therapy and chemotherapy with SST analogues are clearly needed in the near future.

Secretory symptoms from metastatic adrenal cortical carcinoma responding to octreotide

The prognosis of patients with metastatic adrenal cortical carcinoma is poor, and their disabling symptoms are usually unresponsive to conventional therapy. A patient with Cushing's syndrome secondary to a secretory adrenal cortical carcinoma was treated with octreotide, endocrine therapy and chemotherapy having failed. Treatment led to a dramatic relief of her symptoms with a fall in corticosteroid secretion. Somatostatin analogue therapy for this tumour should be encouraged in view of the lack of alternative palliative treatment.

Short-term effects of octreotide on blood pressure and plasma catecholamines and neuropeptide Y levels in patients with phaeochromocytoma: a placebo-controlled trial

OBJECTIVE

The observation that phaeochromocytoma possess specific somatostatin binding sites led us to test the hypothesis that octreotide may have antisecretory potential in patients with phaeochromocytoma. We therefore compared the effects of octreotide and placebo on blood pressure and plasma catecholamines and neuropeptide Y.

PATIENTS

Ten consecutive patients referred to a tertiary care centre for the diagnosis and treatment of a phaeochromocytoma.

DESIGN AND MEASUREMENTS

We performed a crossover comparison of either three 100 micrograms subcutaneous injections of octreotide over one day or 3 injections of octreotide vehicle over another. Blood pressure was measured over 24 hours on each test day using an automatic ambulatory recorder. Blood samples were collected before (at 0800 and 0900 h) and after (at 1000, 1100, 1200, 1300 and 1500 h) placebo or octreotide injection. Plasma catecholamines were assayed by high-performance liquid chromatography and neuropeptide Y was determined using a two-site amplified enzyme immunoassay. All patients then underwent surgery and tumoral somatostatin binding site density was determined by quantitative autoradiography.

RESULTS

Compared to placebo, octreotide did not alter mean 24-hour ambulatory blood pressure or plasma neuropeptide Y, or plasma or urinary catecholamine, levels. Although a moderate reduction in plasma noradrenaline was found in the two patients with the highest tumoral somatostatin binding site densities, overall octreotide-induced variations in plasma noradrenaline did not correlate with somatostatin binding site density. Blood glucose increased from 5.4 +/- 0.3 on placebo to 7.8 +/- 0.5 mmol/l on octreotide (P < 0.01).

CONCLUSION

In the present controlled conditions, short-term administration of octreotide had no antisecretory effect in patients with phaeochromocytoma.

Medical management of hypercalcaemia

1. Hypercalcaemia is a common disorder, which frequently requires specific treatment either to control symptoms, or to prevent the development of irreversible organ damage or death. Although the best and most effective way of controlling hypercalcaemia in the long-term is to treat the underlying cause, medical antihypercalcaemic therapy is often required in clinical practice, either as a holding measure, or because the primary disease cannot itself be treated. 2. The mainstays of medical antihypercalcaemic therapy are firstly, to promote calcium excretion by the kidney by restoring extracellular volume with intravenous saline and secondly, to administer pharmacological agents which inhibit bone resorption. Measures which seek to reduce intestinal calcium absorption are seldom effective. 3. Intravenous bisphosphonates are the treatment of first choice for the initial management of hypercalcaemia, followed by continued oral, or repeated intravenous bisphosphonates to prevent relapse. These drugs have a relatively slow onset of action (1-3 days) but have potent and sustained inhibitory effects on bone resorption, resulting in a long duration of action (12-30 days). 4. Of the other agents available, calcitonin has an important place in the management of severe hypercalcaemia where a rapid effect is desirable; calcitonin is best used in conjunction with a bisphosphonate however, because of its short duration of action. Intravenous phosphate also has a place in the emergency management of severe hypercalcaemia, but is probably best reserved for patients in whom other less toxic therapies have failed. Corticosteroids are generally ineffective except in certain specific instances and are best avoided in the routine treatment of undiagnosed hypercalcaemia.

[Somatostatin in preoperative therapy and postoperative diagnosis of a patient with Verner Morrison syndrome]

We report the case of a patient with Verner-Morrison syndrome due to a malignant MEN I-associated vipoma. Marked tumor-associated hypercalcemia could be treated successfully with somatostatin analogues prior to surgical therapy of the pancreatic tumor. Sixteen months after extirpation of the primary tumor recurrent tumor growth was diagnosed; at this time the patient was clinically asymptomatic and had no abnormal laboratory test results. Liver metastases and local metastases were identified using somatostatin receptor scintigraphy. We report and discuss the use of somatostatin in the treatment of tumor-associated symptoms in endocrine tumors and the possibility of identifying endocrine tumors by means of somatostatin receptor scintigraphy.

Production of calcitonin gene related peptide, calcitonin and PTH-related protein by a prostatic adenocarcinoma

PTH and calcitonin are the two major hormones controlling calcium metabolism. Recently two new substances related to these hormones have been isolated: calcitonin gene related peptide (CGRP) and PTH-related protein (PTHrP). CGRP is a potent vasodilator and stimulant of intestinal secretion while PTHrP is probably the agent responsible for humoral hypercalcaemia of malignancy. We report here a patient with a prostatic tumour presenting with vasodilation, diarrhoea and hypercalcaemia. Our investigations revealed that the primary prostatic and liver secondary tumour contained CGRP, calcitonin and PTHrP. Most of the immunoreactive CGRP in the tumour and plasma co-eluted with the biologically active form of CGRP. The circulating levels of CGRP correlated with the presence of the diarrhoea. PTHrP concentration in the tumours was one of the highest reported for any tumour although previous studies may have utilized less than optimal extraction procedures. The somatostatin analogue, octreotide (SMS 201-995), did not reduce the plasma CGRP or the diarrhoea, a finding similar to that seen in patients with medullary thyroid carcinoma and high plasma CGRP. The hypercalcaemia was also unaffected by octreotide administration. This is the first report of a prostatic tumour associated with over-production of calcitonin, PTHrP and CGRP. The major life-threatening effects of this unusual case of prostatic carcinoma were diarrhoea and hypercalcaemia. Both these effects could be tentatively ascribed to newly discovered substances, CGRP and PTHrP. With the greater availability of assays to measure CGRP and PTHrP in plasma, a detailed examination of the incidence of over-production of these substances in various cancers will be possible.

Multiple recurrent giant cell lesions associated with high circulating levels of parathyroid hormone-related peptide in a young adult

Parathyroid hormone-related peptide (PTHrP, PLP) has previously been identified and assays are now available which can be used in clinical situations. A case is reported of a normocalcaemic young adult female in whom multifocal recurrent giant cell osteolytic lesions in the maxilla and elsewhere were associated with a raised plasma level of parathyroid hormone-related peptide. The lesions were histologically identical to reparative giant cell granuloma of the jaws and to osteitis fibrosa cystica associated with hyperparathyroidism.