Ann Thorac Surg 2002;73:1692-1693
© 2002 The Society of Thoracic Surgeons
Neuroendocrine tumors of the lung and octreotide scintigraphy
Pier Luigi Filosso, MDa,
Ottavio Rena, MDa,
Enrico Ruffini, MDa,
Alberto Oliaro, MDa
a Department of Thoracic Surgery, University of Torino, San Giovanni Battista Hospital, Via Genova, 3, 10126 Torino, Italy
To the Editor
We read with interest "The Image in Cardiothoracic Surgery," by Dr Tovar . Neuroendocrine tumors of the lung express tissue receptors for somatostatin (sst1 through sst5 receptor subtypes), which are detected well by the polymerase chain reaction technique. These receptors are also expressed in recurrences or distant metastases. The role of these receptors has still to be elucidated, but the current generation of somatostatin analogues (octreotide, lanreotide) bind with high affinity to the sst2 receptor subtype, shows a lower affinity to sst3 and sst5, and does not bind to sst4 and sst1 . Thus, tissues expressing sst2 receptors are a potential target for these drugs .
In vivo expression of sst2 receptors is provided by In-DTPA-pentetreotide scintigraphy (Octreoscan); thus tumors expressing a high quantity of sst2 receptors can be detected with a high degree of specificity (Figs 1 and 2).
Octreoscan is effective in detecting both primary neuroendocrine tumors of the lung and mediastinal lymph node metastases with greater accuracy than a thoracic computed tomographic scan .
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Fig 1. Octreoscan showing elective uptake in bone metastasis from resected atypical bronchial carcinoid.|
As we [4, 5] reported in 1997, Octreoscan is effective in the preoperative evaluation of neuroendocrine tumors of the lung and in follow-up. We demonstrated that scintigraphy can detect the tumor and its mediastinal lymph node metastases with high accuracy.
In our preliminary experience with Octreoscan, we observed positive results with scintigraphy also in non-neuroendocrine tumors of the lung (especially undifferentiated large cell carcinomas) . This is probably due to the presence of activated lymphocytes surrounding the tumors that express the sst2 receptor subtype.
Positivity to Octreoscan can influence medical therapy with the current generation of somatostatin analogues (octreotide, lanreotide) in the case of metastatic neuroendocrine tumors. Because of a prolonged circulating half-life and nontoxic side effects, octreotide is an excellent somatostatin analogue for medical applications.
In conclusion, we emphasize the use of In-DTPA-pentetreotide scintigraphy in the preoperative study of neuroendocrine tumors of the lung and during follow-up. We suggest octreotide be used in the treatment of nonresectable recurrences or metastases from these tumors.
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Patel Y.C., Srikant C.B. Subtype selectivity of peptide analogs for all five cloned human somatostatin receptors (hsstr 1-5). Endocrinology 1994;135:2814-2817.[Abstract]
Reisiene T., Bell G.I. Molecular biology of somatostatin receptors. Endocr Rev 1995;16:427-442.[Abstract/Free Full Text]
Oliaro A., Filosso P.L., Bellò M., et al. Use of 111In-DTPA-octreotide scintigraphy in the diagnosis of neuroendocrine and non-neuroendocrine tumors of the lung. Preliminary results. J Cardiovasc Surg (Torino) 1997;38:313-315.[Medline]
Oliaro A., Filosso P.L., Bellò M., et al. Utilizzo della scintigrafia con octreotide marcato nella diagnosi delle recidive di tumori neuroendocrini del polmone. Risultati preliminari. Chirurgia 1997;10:177-179.