Nuclear medicine in the assessment of differentiated thyroid cancer

A phase I study of pazopanib in combination with escalating doses of 131I in patients with well-differentiated thyroid carcinoma borderline refractory to radioiodine

OBJECTIVE

This trial was conducted to evaluate the ability of pazopanib to overcome therapeutic 131I resistance.

MATERIALS, METHODS AND PATIENTS

This phase 1 trial assesses the combination of pazopanib and escalating doses of radioiodine (131I) in patients with recurrent or metastatic thyroid cancer that are borderline or relatively iodine refractory. Radioiodine uptake scans were assessed post therapy and compared to historical pre-treatment scans. Patients underwent FDG PET/CT before and after the initial pazopanib treatment to identify the impact of pazopanib on the cancer prior to 131I therapy.

RESULTS

A dose limiting toxicity (cardiac arrhythmia and grade 3 fatigue) in the first patient in the first cohort prompted expansion to a total of 6 patients. Additional grade 3-4 hematologic toxicity and low accrual in the expanded cohort led to the decision not to pursue further study of the regimen. In patients with measurable disease 4/5 (80%) achieved stable disease. Median progression free survival was 6.7 months. At 3 years of follow up, one patient died due to progressive disease, two are being treated with systemic therapy and 3 continue without requiring subsequent therapy at 15, 27 and 35 months from the last dose of pazopanib. There was no convincing impact of pazopanib on iodine uptake in scans performed pre- and post-therapy compared to scans from historical 131I treatments without pazopanib.

CONCLUSION

Despite a suggestion of therapeutic efficacy, combined pazopanib and 131I resulted in increased toxicity. There was no convincing evidence that the administration of pazopanib improved iodine uptake or retention.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01413113.

Relation between (99m)Tc-tetrofosmin thyroid scintigraphy and mitogen-activated protein kinase in papillary thyroid cancer patients

PURPOSE

The aim of this study was to investigate the relation between (99m)Tc-tetrofosmin uptake and extracellular signal-regulated kinase mitogen-activated protein kinase (ERK MAPK) expression in papillary thyroid cancer patients.

MATERIALS AND METHODS

Our study population consisted of 14 patients. The histopathological findings for all patients were confirmed by surgery. Patients were administ 740 MBq of (99m)Tc-tetrofosmin. The tumor/background (T/B) ratios in regions of interest (ROIs) were measured at 10 min, 1 h, and 3 h to determine the uptake by papillary cancer. Immunohistopathological staining was performed, and the expression of phospho-ERK MAPK in papillary cancer was investigated. The relation between the expression of phospho-ERK MAPK and the T/B ratio was examined using the Mann-Whitney U-test.

RESULTS

(99m)Tc-tetrofosmin uptake was positive in all patients. There was a statistically significant relation between the T/B ratio (at 3 h) and the expression of phospho-ERK MAPK but not with the T/B ratio at 10 min or 1 h: T/B ratio at 10 min (P = 0.32), at 1 h (P = 0.62), and at 3 h (P = 0.0072).

CONCLUSION

Our results suggest that the relation between (99m)Tc-tetrofosmin uptake (3 h T/B ratio) may lead us to assume cell proliferation of papillary cancer.

The comparison of (131)I whole-body scans on the third and tenth day after (131)I therapy in patients with well-differentiated thyroid cancer: preliminary report

OBJECTIVE

The purpose of the present study was to evaluate the clinical usefulness of the delayed post-therapeutic (131)I scan in patients with well-differentiated thyroid cancer by comparing the early scanned images with the delayed images.

METHODS

A total of 81 patients (female:male = 67:14; age 52 ± 13 years) with well-differentiated thyroid cancer who underwent scans the third and tenth day after (131)I treatment were included in this study. The therapeutic dose ranged from 3.7 GBq (100 mCi) to 7.4 GBq (200 mCi). The early and delayed scan images were visually analyzed and the thyroid remnant-to-background uptake ratio (RBR) and the lesion-to-background uptake ratio (LBR) of metastatic lesions were calculated.

RESULTS

Of the 81 patients, 5 lesions (2 lung lesions, 2 cervical lymph node lesions, and one thyroid remnant) in 4 patients (5%) were additionally found on the delayed scans, which were not identified on the early scans. Of 8 patients with high serum thyroglobulin (Tg) and negative finding on the early scan, the delayed scan identified additional lesions in 3 patients (38%). Visual analysis scores significantly decreased for both thyroid remnants and metastatic lesions on the delayed scan (p < 0.001 for all). Diffuse hepatic uptake was visualized in 86% of all patients on the delayed scan, while only 6% of the patients on the early scan (p < 0.001). The RBRs of both scans were compared in 59 patients, and the LBRs were compared in 8 patients with 23 lesions. The mean RBR and LBR on the delayed scan (8.0 ± 7.6 and 5.4 ± 5.2, respectively) were significantly lower than those on the early scan (12.0 ± 10.8 and 10.8 ± 7.6, respectively; p = 0.02 and p = 0.001, respectively).

CONCLUSIONS

The (131)I-avid lesions on the early scan were more easily detected by visual analysis and had higher uptake ratios than those on the delayed scan. However, for patients with high serum Tg and negative finding on the early scan, the delayed scan was helpful in identifying additional (131)I-avid lesions.