Relationship among (201)T1 uptake, nuclear DNA content and clinical behavior in metastatic thyroid carcinoma

A prospective study of Tl-201 uptake was performed to compare Tl-201 uptake with nuclear deoxyribonucleic acid (DNA) content and clinical behavior of tumors in metastatic thyroid carcinoma and to assess the significance of Tl -201 uptake in evaluating clinical characteristics of thyroid carcinoma. Me thods: Fifty-six patients with metastases of differentiated thyroid carcino ma had Tl-201 scintigraphy. Grade of Tl-201 uptake was semiquantitatively a ssessed according to tumor-to-background ratio on 2-h late scan. Nuclear DN A content was analyzed within 3 wk of Tl-201 study by flow cytometry using biopsy material and was classified as diploidy or aneuploidy. Patients were followed up to examine incidence of tumor growth and/or anaplastic transfo rmation. Results: DNA content was diploidy in 48 patients and aneuploidy in 8 patients. Tl-201 uptake in the DNA-aneuploid group (2.61 +/- 0.29) was s ignificantly higher than that in the DNA-diploid group (1.82 +/- 0.35, P < 0.01 for both groups). Tumor growth was observed in ail patients with DNA a neuploidy but in only 5 of 48 patients with DNA diploidy (P < 0.01). Anapla stic transformation was observed in 3 patients in the DNA-aneuploid group b ut in none of the patients in the DNA-diploid group. Conclusion: High Tl-20 1 uptake indicates greater incidence of abnormal DNA content with aggressiv e clinical behavior of metastatic tumors. Thus, Tl-201 scintigraphy may be useful in characterizing metastatic thyroid carcinoma and in identifying th ose patients with poorer prognoses.