SOMATOSTATIN RECEPTOR IMAGING - PREDICTIVE AND PROGNOSTIC CONSIDERATIONS

Compared with other imaging modalities and clinical investigation, the In-111-pentetreotide scan identified additional metastatic disease si tes in 12 carcinoid patients and 2 occult primaries, and influenced th e therapeutic outcome in 36 patients [29 carcinoids. 2 atypical carcin oids, 3 cancers of unknown primaries (CUPs) and 2 medullary thyroid ca rcinomas (MCTs)]. No adverse ed reactions were noted. Somatostatin rec eptors were detected in 59/60 carcinoid patients, 314 atypical carcino id patients, 0/2 MCT patients, and 0/3 cases of CUP. Somatostatin rece ptor presence is underestimated in some patients using standard hormon al response criteria rather than scintigraphy. 18 patients with metast atic carcinoids who underwent In-111-pentetreotide scanning were all s omatostatin receptor positive. Their mean (+/- SE) 5-hydroxyindoleacet ic acid (5-HIAA) suppression with octreotide therapy was -53% (+/- 6%) , 8 patients had <50% and 10 had >50% 5-HIAA suppression (ranges: -4 t o -47% and -58 to -94%, respectively). To investigate the effect of so matostatin analogues on survival, 90 consecutive cases of carcinoid sy ndrome patients treated during the somatostatin analogue era were revi ewed. Survival according to primary site was 12.01, 18.29 and 6.05 yea rs (overall median 12.01 years) for patients with foregut, midgut and unknown primaries, respectively. The difference from historical contro ls is substantial (67 vs. 18% 5-year survival), although our series is neither prospective nor randomised. The heterogeneity in patient and tumour response to somatostatin analogue therapy is discussed.