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The study was set up to determine the clinical value of dihydroxyphenylalanine positron emission tomography-computed tomography ([18F]DOPA PET-CT) in patients with neuroendocrine tumors (NETs). Eighty-two patients with suspected/known NET were imaged with PET(-CT) using [18F]DOPA. Patients were divided into two groups: primary diagnosis/staging and restaging of disease. All patients without previous diagnosis of NET had biochemical proof of disease. The diagnostic accuracy of PET was assessed by comparing the histopathology and clinical follow-up. The overall accuracy of [18F]DOPA PET was 90%. In patients having PET for primary diagnosis/staging (n=32), the accuracy of PET was 88%, and for restaging 92% (n=61). The mean s.d. sizes of primary and metastatic lesions detected by PET were 26±11 and 16±9 mm respectively. In organ-region-specific analysis, the sensitivity and specificity were 100% in the primary diagnosis of pheochromocytoma (n=16) and metastases were found in all cases with recurrent disease (n=5). The accuracy for NET of gastrointestinal tract was 92% in restaging (n=24). For the NETs located in the head–neck–thoracic region (n=19), the overall accuracy of PET was 89% including 12 cases of recurrent medullary thyroid cancer with a sensitivity of 90%. In analysis of patients with biochemical proof of disease combined with negative conventional imaging methods, PET had positive and negative predictive value of 92% and 95% respectively. [18F]DOPA PET-CT provided important additional information in the diagnosis of pheochromocytoma and restaging of known NET. Both in primary diagnosis and in patients with formerly known NET and increasing tumor markers, [18F]DOPA PET-CT is a sensitive first-line imaging method.

Differentiated thyroid carcinomas (DTC) (papillary, follicular and follicular type of papillary) have a favourable prognosis, but a proportion of patients develop recurrences and eventually die of the disease. Various prognostic factors have been identified and been used to create the current staging classifications (AGES, AMES, MACIS, EORTC, UICC-TNM). We examined 499 DTC patients retrospectively to validate known prognostic factors that enable them to be recognised as having either a low or a high risk of death related to a recurrence of DTC, by reference to the current staging classifications. Sixty-nine of them (14%) had local or distant recurrences, the mean time to recurrence being 7.7 years. The 10-year disease-free survival rate was 80%, and the ten-year overall survival rate for the entire group was 91%, with a mean survival time of 8.7 years. Male gender, a follicular type of tumour, larger tumour size, extrathyroidal invasion outside the capsule and nodal metastases were all related to a higher incidence of tumour recurrence, and the follicular type of histology, age >45 years, larger tumour size and local invasion entailed poorer survival. The AMES and to some extent the EORTC classification were not reproducible in this material, mainly because some prognostic variants were no longer encountered or were insufficient in number to allow reliable conclusions to be drawn. The MACIS staging classification leaves the definition of the intermediate and high risk groups too wide and is therefore not very reliable. Pooling of stages I and II improved the relevance of the TNM classification. All the current staging classifications are able to discern a low risk DTC group well. We achieved a highly accurate definition of risk in the present material using only two parameters, age (cut-off value 50 years) and extracapsular invasion of the thyroid gland.