抄録
Of 139 patients with metastasis resulting from differentiated thyroid cancer, 16 (11.5%) who underwent 131I therapy five times or more were assessed for therapeutic results, therapeutic intervals and side effects.
Of the 16 patients (2 males and 14 females), 10 suffered from papillary carcinoma and 6 from follicular carcinoma. In terms of the metastatic site, 7 were lung metastatic cases, 4 bone metastasis and 5 both lung and bone metastases. The therapeutic results were as follows: none (0%) of the patients were cured, 50% improved (Group A), 19% showed no change (Group B), and 31% showed deterioration and died (Group C).
The onset of the first symptom occurred at the age of 22±7 years in Group A, 29±14 years in Group B and 52±14 years in Group C. Group A received initial therapy at 29±6 years of age, Group B at 39±24 years and Group C at 54±14 years. The serum Tg level in Group A continuously declined by repetitive 131I therapy and the ratio (serum Tg level after the last 131I therapy/Tg level before 131I therapy) was significantly lower (P<0.01) in Group A (17±13%) than that in Group B (59±39%) and in Group C (131±121%).
The reduction rate of serum Tg level was 42±15%with 131I therapy given twice yearly and 17±22% once yearly. The difference was significant (P<0.02). Side effects were hardly shown.
From these results, it may be concluded that frequent 131I therapy is more effective among the subjects in Group A, who started the initial therapy when younger than 30 years of age, and underwent subsequent 131I therapy once every 6 months, and that a successive decline in serum Tg levels is a useful marker for a good prognosis.
