Comparative studies on the expression of somatostatin receptor subtypes, outcome of octreotide scintigraphy and response to octreotide treatment in patients with carcinoid tumours.

• We have compared the expression of somatostatin receptor (sstr) subtypes with the outcome of somatostatin receptor scintigraphy and the effect of somatostatin receptor activation in patients with disseminated carcinoid tumours. Tumour tissues from nine patients with midgut carcinoids (ileal) and three patients with foregut carcinoids (gastric, thymic) were analysed using Northern blotting. Expression of somatostatin receptors was demonstrated in all tumours (12 out of 12), with all five receptor subtypes present in 9 out of 12 tumours. Somatostatin receptor scintigraphy using [111In]DTPA-D-Phe1-octreotide visualized tumours in all patients (12 out of 12). The 111In activity concentrations in tumour tissue (T) and blood (B) were determined in three tumours 1-7 days after injection of the radionuclide. The T/B 111In activity concentration ratios ranged between 32 and 651. Clinically, treatment with the long-acting somatostatin analogue octreotide resulted in marked symptom relief accompanied by a significant reduction in tumour markers, for example urinary-5-HIAA levels (28-71% reduction). Incubation of midgut carcinoid tumours in primary culture with octreotide (10 microM) resulted in a reduction in spontaneously secreted serotonin (45-71% reduction) and 5-HIAA (41-94% reduction). The results demonstrate that carcinoid tumours possess multiple somatostatin receptor subtypes and that somatostatin analogues such as octreotide, which preferentially bind to somatostatin receptor subtype 2 and 5, can be used in the diagnosis and medical treatment of these tumours. In the future, novel somatostatin analogues with subtype specific receptor profiles may prove to be of value for individualizing the treatment of disseminated carcinoid tumour disease.

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Kirurgi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Surgery (hsv//eng)

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Cancer och onkologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Cancer and Oncology (hsv//eng)

Keyword

Aged

Antineoplastic Agents

Hormonal

therapeutic use

Carcinoid Tumor

chemistry

drug therapy

metabolism

radionuclide imaging

Female

Gastrointestinal Agents

diagnostic use

Gastrointestinal Neoplasms

chemistry

drug therapy

metabolism

radionuclide imaging

Humans

Ileal Neoplasms

chemistry

drug therapy

metabolism

radionuclide imaging

Indium Radioisotopes

pharmacokinetics

Male

Middle Aged

Neoplasm Proteins

analysis

Octreotide

diagnostic use

therapeutic use

Receptors

Somatostatin

analysis

Stomach Neoplasms

chemistry

drug therapy

metabolism

radionuclide imaging

Thymus Neoplasms

chemistry

drug therapy

metabolism

radionuclide imaging

Publication and Content Type

ref (subject category)

art (subject category)