Therapeutic implications of diffuse hepatic uptake following I-131 therapy for differentiated thyroid cancer

To determine if diffuse hepatic uptake (DHU) of radioactive iodine (I-131) following radioactive iodine treatment has prognostic implications in otherwise scan-negative patients.

This is a retrospective review of patients treated for differentiated thyroid cancer (DTC) at Beth Israel Deaconess Medical Center between January 1990 and June 2006. This group included patients receiving therapy to ablate presumed remnant tissue, as well as treatment for persistent disease as measured by thyroglobulin or imaging. All patients included in the study had no remnant uptake and otherwise negative posttherapy scans. A total of 57 patients with 63 scans met these criteria. The scans were then scored for DHU on a scale of 0 to 5, with 0 being no uptake and 5 being intense uptake relative to background.

Sixteen of 63 treatments were remnant ablations. Ten of 57 patients had positive thyroglobulin antibodies. Average DHU was similar in the ablation and therapeutic groups (1.9 vs. 2.3, P = .3). There was no correlation with either I-131 dose or the presence of thyroglobulin antibodies. There was a difference for DHU in the rate of disease-free survival, (undetectable thyroglobulin and no clinical or radiographic evidence of metastasis); 50% of patients with hepatic uptake scores of 0-2 were disease-free compared to 15% with scores of 3-5 (P<.01). The average length of follow-up for disease-free patients was 4.6 years.

In patients with DHU with otherwise negative whole-body scans following I-131 treatment, more intense hepatic uptake is associated with lower likelihood of complete response to I-131 treatment.