Introduction/background

Patients with radioiodine-refractory differentiated thyroid carcinoma (RR-DTC) have limited treatment options. Since expression of somatostatin receptors and uptake on somatostatin scintigraphy is observed in a subset of these patients, peptide receptor radionuclide therapy (PRRT) is a potential treatment option.

Aims

To evaluate the effect of PRRT in RR-DTC patients on disease progression and survival.

Material and Methods

A retrospective analysis was performed on 27 RR-DTC patients treated with ¹⁷⁷Lu-DOTATATE between 2000 and 2019 in our center. Selected patients had progressive disease before PRRT and all but one had an uptake equal to or higher than the liver on somatostatin scintigraphy.

Results

Tumor subtypes consisted of four papillary, nine follicular and 14 Hürthle cell carcinomas. Every included patient did undergo thyroid surgery and received at least one radioactive Iodine-131 treatment. In 24 patients distant metastases (mainly to lung, lymph nodes and bone) were present. Patients were diagnosed with DTC a median of 39 months prior to PRRT. The cumulative administered dose of PRRT ranged between 11.1 and 29.6 GBq (median 22.2 GBq).

The best response was partial response, stable disease and progressive disease or death in 11%, 52% and 26% of the patients, respectively. Median progression-free survival was 10 months after the start of PRRT and median overall survival was 34 months. Time to biochemical progression did not differ from time to morphological progression. Grade 3 and 4 hematological toxicity occurred in five patients and one patient, respectively. No grade 4 renal toxicity or other serious adverse events were observed.

Conclusions

RR-DTC patients may benefit from PRRT if there is sufficient uptake on somatostatin scintigraphy. PRRT could form a potential safe alternative to tyrosine-kinase inhibitors for this indication.

Use of keywords in abstract text

peptide receptor radionuclide therapy, iodine-refractory, differentiated thyroid carcinoma