What is the impact of pre-ablation 131-I scintigraphy with SPECT-CT on thyroid cancer management?

Objectives The objective of this study is to determine the contribution of preablation 131-I scans with SPECT-CT (Dx scans) to the management of patients with differentiated thyroid cancer (DTC).

Methods Using American Thyroid Association (ATA) risk stratification an endocrinologist determined post-operative management in 320 patients (pts) (219F; 101M, mean age 47.3 ± 16.4, range 10 - 90) with DTC (289 papillary, 22 follicular and 9 Hurthle cell tumors) based on clinical and surgical pathology (pTNM) information. Dx scans were performed and interpreted by 2 nuclear medicine physicians as showing thyroid remnant, cervical nodal, or distant metastases. The endocrinologist re-assessed the management strategies incorporating the findings from Dx scans and stimulated thyroglobulin. The decision to withhold or to administer 131-I treatment (RAI) and the prescribed 131-I activity: low (30 - 50 mCi); medium (100-150 mCi) and high (200+ mCi) dose 131-I therapy, were recorded.

Results Based on ATA risk stratification the decision to withhold RAI occurred in 60/320 pts (19%), while for 260/320 pts (81%) RAI was recommended as follows: low dose in 39 pts, medium dose in 220 pts, and high dose in 1 pt. Dx scans detected regional metastases in 112/320 pts (35%) and distant metastases in 24/320 pts (8%) of patients. After review of Dx scan information, the endocrinologist referred 19 additional pts for RAI, 8 pts for surgical debulking and withheld RAI in 3 additional pts. This resulted in recommendation for 52/320 pts (16%) to be withheld RAI, and 268/320 pts (84%) to receive RAI as follows: low dose in 55 pts, medium dose in 189 pts, and high dose in 24 pts.

Conclusions Information obtained with preablation 131-I scans with SPECT-CT led to a change in management in 99/320 pts (31%). Pre-ablation scans provide incremental information for risk stratification and patient management.