Outcome of Differentiated Thyroid Cancer with Detectable Serum Tg and Negative Diagnostic 131I Whole Body Scan: Comparison of Patients Treated with High 131I Activities Versus Untreated Patients

F. Pacini
2001 Journal of Clinical Endocrinology and Metabolism  
Detectable serum Tg levels associated with negative diagnostic 131 I whole body scan are not infrequently found in patients with differentiated thyroid cancer. Several researchers have shown that in these patients the administration of high 131 I activity (100 mCi or more) increases the sensitivity of a posttherapy diagnostic 131 I whole body scan performed a few days later and allows the detection of neoplastic foci not seen with diagnostic doses of 131 I. Empirical radioiodine treatment has
more » ... ine treatment has also been advocated by some researchers, but its therapeutic effect is controversial. In our institute, positive serum Tg/negative diagnostic 131 I whole body scan patients were not treated with high 131 I activities before 1984; afterward, almost all patients with positive serum Tg/negative diagnostic 131 I whole body scan patients were treated with radioiodine, and a posttherapy diagnostic 131 I whole body scan was performed. In the present retrospective study we compared the outcome of these two groups of patients, 42 treated and 28 untreated, followed for mean periods of 6.7 ؎ 3.8 and 11.9 ؎ 4.4 yr, respectively. In the treated group the first posttherapy diagnostic 131 I whole body scan was negative in 12 patients and positive in 30 patients. 131 I treatment was further administered only in the latter group. At the end of follow-up in treated patients a complete remission (normalization of serum Tg off L-thyroxine and negative diagnostic 131 I whole body scan) was observed in 10 patients (33.3%). In 9 cases (30%) posttherapy diagnostic 131 I whole body scan became negative, and serum Tg was reduced but still detectable; in 11 patients (36.6%) serum Tg was de-
doi:10.1210/jc.86.9.4092 pmid:11549631 fatcat:h3ymadrbhnhbjdemsc3teuhsoe