Clinical diagnostic application of In-111-DTPA-octreotide scintigraphy in small cell lung cancer

Some years ago it was proved that a good percentage of small cell lung canc ers, classified among cancers of the APUD system, produces somatostatin rec eptors that can be detected in vivo by scintigraphy with In-111-DTPA-octreo tide. With the method in the whole body it is possible to identify the prin cipal neoformation and the probable metastases. The authors present a study of 21 patients afflicted with small cell lung cancer diagnosed histologica lly. The study, carried out between January 1995 and December 1997, compare d the radiologic iconography of the CT scan with the scintigraphic map obta ined by a planar scintigraphy and in SPECT 1, 4 and 24-hr after iv injectio n of 110 MBq of In-111-DTPA-octreotide. The comparison was made with refere nce to the principal neoplasm and probable metastases. A scintigraphic stud y, a CT of restaging and a follow-up, done after 3 and 6 months of chemothe rapy, on 15 patients with cancer that produces somatostatin receptors prove d that the neoplasm sometimes regresses and sometimes progresses. In the la tter case, it is possible to identify cerebral, mediastinal and hepatic met astases with the administration of 200 mu g of octreotide 3 times a day for 7 days before the scintigraphy. In fact, the administration lowers backgro und activity. The authors concluded that scintigraphy with In-111-DTPA-octr eotide plays an important part in the study of patients afflicted with smal l cell lung cancer. Scintigraphy identifies the subgroups of patients who c an be cured with somatostatin analogues together with chemotherapy. Scintig raphy presents a good sensibility in the re-staging and in the follow-up of patients who are treated, even though it is difficult to identify subdiaph ragmatic metastases where liver, spleen and kidney show an increase in In-1 11-DTPA-octreotide.