Medical Treatment of Neuroendocrine Tumors

Effect of Octreotide on Neuroenolase Levels in Patients with Small Cell Lung Cancer

Aims and Background

The somatostatin analog octreotide has an antiproliferative effect on small cell lung cancer lines in vitro and in experimental xenograft transplantation systems in vivo. Thus it is worth investigating octreotide activity in the clinical setting.

Methods

We studied the effect of octreotide (200 μg three times a day subcutaneously for seven days) on serum levels of the tumor marker neuroenolase in 13 patients with small cell lung cancer.

Results

A decrease in neuroenolase levels was observed at day 7 during octreotide treatment, with a mean ± SD of 32.6 ± 42.0 ng/ml compared to basal values of 44.4 ± 57.7 ng/ml and to washout values of 50.3 ± 65.7 ng/ml ( P < 0.03).

Conclusions

Our results indicate that octreotide is effective in reducing neuroenolase levels in small cell lung cancer patients. These data suggest a possible role for octreotide in the treatment of this kind of tumor.

Neuroendocrine tumours metastatic to the uvea: diagnosis by fine needle aspiration biopsy

BACKGROUND

Uveal metastasis from a neuroendocrine tumour is rare and can simulate other primary or metastatic uveal tumours, both clinically and cytomorphologically. We describe four cases of uveal metastasis from a neuroendocrine tumour diagnosed by fine needle aspiration biopsy (FNAB).

METHODS

Four patients were referred for evaluation of a recently detected fundus mass. Two patients had a history of malignant, non-ocular, neuroendocrine neoplasms (Merkel cell carcinoma and lung carcinoid in one patient each). The third patient had a mediastinal mass that had been biopsied inconclusively, while the last patient reported a persistent cough.

RESULTS

Ophthalmic examination revealed an amelanotic ciliochoroidal mass in 2 cases and a lightly melanotic and a pale orange choroidal mass in 1 case each. Partial, non-rhegmatogenous, retinal detachment was present in 3 patients. Ocular ultrasonography revealed moderate to high internal reflectivity of the mass in 3 cases and low internal reflectivity in the 4th. Our differential diagnosis in all cases was metastatic carcinoma versus primary uveal melanoma. FNAB of the intraocular mass was performed in all patients to establish a pathologic diagnosis and guide subsequent management. Cytomorphology and immunohistochemical profiles of the aspirates were consistent with metastatic neuroendocrine neoplasms in all patients. Our final diagnosis was metastatic lung carcinoid in 2 patients and metastatic Merkel cell carcinoma and small cell lung carcinoma in 1 patient each. Immediately after FNAB, the intraocular tumour was treated by plaque radiotherapy (3 patients) or fractionated external beam radiotherapy (1 patient). All tumours treated regressed satisfactorily. Two patients expired due to widespread lung carcinoid 11 and 12 months after our initial evaluation respectively. The other two patients are still alive after 38 and 64 months respectively.

CONCLUSIONS

Neuroendocrine tumours are a heterogeneous group of neoplasms whose diagnosis ultimately depends on the identification of specific cell markers (e.g., neuron-specific enolase, chromogranin, synaptophysin), hormones and neurotransmitters (e.g., gastrin, serotonin, adrenocorticotrophic hormone [ACTH]). FNAB with immunohistochemical stains for neuroendocrine markers can establish a pathologic diagnosis in cases of uveal metastasis from a neuroendocrine tumour. To our knowledge, our patient with Merkel cell carcinoma is the first pathologically proven case of uveal metastasis from this primary malignancy.

The diagnosis and medical management of advanced neuroendocrine tumors

Neuroendocrine tumors (NETs) constitute a heterogeneous group of neoplasms that originate from endocrine glands such as the pituitary, the parathyroids, and the (neuroendocrine) adrenal, as well as endocrine islets within glandular tissue (thyroid or pancreatic) and cells dispersed between exocrine cells, such as endocrine cells of the digestive (gastroenteropancreatic) and respiratory tracts. Conventionally, NETs may present with a wide variety of functional or nonfunctional endocrine syndromes and may be familial and have other associated tumors. Assessment of specific or general tumor markers offers high sensitivity in establishing the diagnosis and can also have prognostic significance. Imaging modalities include endoscopic ultrasonography, computed tomography and magnetic resonance imaging, and particularly, scintigraphy with somatostatin analogs and metaiodobenzylguanidine. Successful treatment of disseminated NETs requires a multimodal approach; radical tumor surgery may be curative but is rarely possible. Well-differentiated and slow-growing gastroenteropancreatic tumors should be treated with somatostatin analogs or alpha-interferon, with chemotherapy being reserved for poorly differentiated and progressive tumors. Therapy with radionuclides may be used for tumors exhibiting uptake to a diagnostic scan, either after surgery to eradicate microscopic residual disease or later if conventional treatment or biotherapy fails. Maintenance of the quality of life should be a priority, particularly because patients with disseminated disease may experience prolonged survival.

Expression of p68 protein kinase and its prognostic significance during IFN-alpha therapy in patients with carcinoid tumours

The aim of this study was to evaluate the antiproliferative effects of interferon alpha (IFN-alpha) on neuroendocrine differentiated cell lines and, retrospectively, to assess the prognostic significance of p68 protein kinase (PKR) induction in neuroendocrine gut and pancreatic tumour patients. Archive specimens from 56 patients were studied, 43 before IFN-alpha and 56 during therapy. The tissues were immunostained for p68 protein kinase (PKR) using the monoclonal antibody (MAb) TJ4C4. A significant increase in immunostaining after treatment with IFN-alpha compared with before treatment (3.47 +/- 0.12 versus 2.72 +/- 0.15, P < 0.001) was noted. The p68 score was significantly increased after treatment only in patients with stable disease before = 2.71 +/- 0.19, after = 3.40 +/- 0.14 (P < 0.001) or an objective response before 3.13 +/- 0.22, after = 4.00 +/- 0.24 (P < 0.05) but not in those with progressive disease (before = 2.32 +/- 0.24, after 2.86 +/- 0.26, NS). A low p68 score (< 3.0) during treatment was a predictor of shorter duration of response and overall survival (P = 0.0062 and P < 0.0001, respectively). Furthermore, IFN-alpha showed a significant antiproliferative effect (by [3H]thymidine incorporation) on two carcinoid tumour cell lines in a dose-dependent manner which correlated with a dose-dependent induction of p68 mRNA and protein expression (by Northern and Western blot analysis). We conclude that IFN-alpha can effectively inhibit the in vitro growth of carcinoid tumor cell lines and upregulates the expression of p68 at both mRNA and protein levels in carcinoid tumours. The induction of p68 could be a prognostic indicator of response in patients with carcinoid tumours during IFN-alpha treatment.

Neuroendocrine differentiation in prostatic malignancy

BACKGROUND

The prostatic neuroendocrine cell is a regulatory cell that produces serotonin and peptide hormones. This cell is part of a more widely dispersed diffuse neuroendocrine regulatory system known as the APUD system. Focal neuroendocrine differentiation is seen in virtually all prostate carcinomas to one degree or another. Specific malignancies that are purely neuroendocrine include small cell carcinoma and carcinoid/carcinoid-like tumors. A variety of studies suggest a possible prognostic significance of neuroendocrine differentiation in prostate carcinoma.

METHODS

The literature on the prostatic neuroendocrine cell and neuroendocrine differentiation in prostate carcinoma is reviewed.

RESULTS

Based on analogy with other better studied elements of the diffuse neuroendocrine regulatory system or APUD system, as well as the morphology and specific products produced by neuroendocrine cells, it is likely that they play an important regulatory role in the prostate. Neuroendocrine differentiation may be of prognostic significance in prostate carcinoma. Mechanisms are not well characterized at this point, but the known growth factor activity of the neuroendocrine cell products, an increase in proliferation in cells surrounding neuroendocrine cells, and a lack of androgen receptor expression in neuroendocrine cells, suggest mechanisms by which they may be of prognostic significance.

CONCLUSIONS

Neuroendocrine differentiation in prostate carcinoma may be of prognostic significance, but better methods to define neuroendocrine, differentiation are necessary. The therapeutic implications of neuroendocrine differentiation in prostate carcinoma may be of significance and need to be explored further.

Clinical efficacy of octreotide in the treatment of metastatic neuroendocrine tumors. A study by the Italian Trials in Medical Oncology Group

BACKGROUND

The unsatisfactory control of neuroendocrine tumor growth with chemotherapy and/or interferon (IFN-2a) stimulated us to investigate the role of the somatostatin analogue octreotide (SMS 201.995), which is reported to be highly effective in controlling carcinoid syndrome symptoms. Octreotide has been used in a wide range of doses, and it was postulated that higher doses might lead to an objective response.

METHODS

The aim of the present multicenter Phase II study was to determine the safety and efficacy of SMS 201.995 in controlling carcinoids and other neuroendocrine tumors. Fifty-eight patients were treated subcutaneously with 2 sequential doses of the drug (Sandostatina, Sandoz, Inc., S.b.A. Pharmaceuticals, Basel, Switzerland). The first 23 patients received 500 micrograms 3 times a day and the remaining 35 patients received 1000 micrograms 3 times a day. The treatment was continued until the tumor progressed.

RESULTS

All of the patients were adequately treated and evaluated. The predominant histotype was carcinoid, although there were instances of medullary thyroid carcinoma, pancreatic islet cell tumors, and Merkel cell carcinoma. Carcinoid syndrome was documented in 16 patients and abnormal urinary 5-hydroxyindoloacetic acid excretion in 15. The median treatment duration was 5 months (range, 2-31 months). The responses were evaluated in three categories: tumor regression for tumor growth control, symptom response, and biochemical response. There was an effect on tumor growth in two patients with carcinoids. Symptomatic control was achieved in 73% of patients and a biochemical response in 77% of patients. In twenty-seven patients, the disease stabilized for at least 6 months (range, 6-32+). The median survival time for all patients was 22 months (range, 1-32+).

CONCLUSIONS

In terms of tumor regression, octreotide is disappointing (partial response: 3%); symptomatic response and biochemical control are satisfactory. These data confirm that somatostatin analogues are comparable to interferons in the treatment of carcinoid syndrome, although other efforts are necessary to control tumor regression.