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Mazzaferri, Columbus, OH, USA, gave an overview of the impact of initial
tumor features and performed treatment on the longterm course of patients
with differentiated thyroid cancer. In their experience based on 1355 patients
and a median follow-up period of 16 years the overall mortality is only
5% in contrast to a four times higher cancer recurrence rate. The mean
tumor size was 2.5 cm, multiple intrathyroidal tumors were found in 24%
of patients, cervical metastases in 42% and distant metastases in only
2% at diagnosis and during follow-up another 5%. The recurrence rate in
patients with primary tumors greater than 1.5 cm, multiple intrathyroidal
tumors or cervical metastases was significantly lower if thyroid remnant
l3ll ablation had been applied.
Konishi, Kyoto, Japan, discussed the much higher sensitivity and quality of 99mTc Sestamibi scintigraphy in comparison with the use of 20lTl for the detection of metastases in lung, lymphnodes and bone. Furthermore, he and Pacini, Pisa, Italy, elaborated on the efficacy of l3lI therapy of metastatic disease. The more differentiated the metastases are, the higher is the iodine accumulation and its effect (often in less severe hypothyroid patients), whereas patients with bone metastases show anyhow an unfavourable prognosis. A special issue was l3lI treatment in patients, who underwent thyroidectomy and remnant l3lI ablation in the past, with detectable Tg levels and a negative low dose l3lI whole body scan (WBS) (about 13% of all patients studied with Tg measurement and WBS). More than 90 % do show l3lI uptake on WBS in the metastases after therapeutic doses of l3lI and with favourable effects in many patients, based on decrease in Tg levels, normalization of CT scans and negative radioiodine scans during follow-up. However, its effect on survival in this group of patients is unknown. These findings underline the importance of dosimetric aspects, which were discussed by Maxon, Cincinnati, OH, USA. For small sized metastases he suggested the use of 125I instead of l3lI because of the (very) short range of the Auger electrons, thereby lowering the radiation dose to normal tissues. Another aspect was the risks induced by high doses of l3lI. Although the reported findings, e.g. induction of leukemia, are inconsistent, his advise was to perform surgery whenever possible. |
