The Feasibility of High Dose Iodine 131 Treatment as an Alternative to Surgery in Patients with a Very Large Goiter: Effect on Thyroid Function and Size and Pulmonary Function*

Abstract

Abstract Some patients with very large goiters (>150 mL) are not candidates for surgery. We evaluated the feasibility of high dose 131I in such patients. Twenty-three patients (2 men and 21 women; median age, 67 yr; range, 42–86 yr) with very large goiter (8 toxic) were treated with calculated high dose 131I [median, 2281 megabecquerels (61.6 mCi); range, 988-4620 megabecquerels (26.7–124.9 mCi)]. During the 12-month observation period, goiter reduction and tracheal anatomy were monitored by magnetic resonance imaging, and the respiratory capacity was monitored by pulmonary function tests. Five patients (22%) developed hypothyroidism. Thyroid volumes were at baseline, after 1 week, and after 1 yr [mean ± sem, 311 ± 28, 314 ± 26 (P = NS), and 215 ± 26 (P < 0.01) mL]. The relative changes 1 week after therapy ranged from −14.1% to 15.3%. After 1 yr the mean size was reduced by 33.9% (range, 13.5–61.4%). Only the initial goiter size showed a significant negative correlation to the percent reduction. The smallest cross-sectional area of the trachea decreased 9.2% within 1 week after treatment, but eventually emerged with a 17.9% larger area [mean ± sem, 84.3 ± 4.8, 75.5 ± 5.1 (P < 0.01), and 98.2 ± 6.0 (P < 0.01) mm2]. The inspiratory parameter, FIF50%, improved after an initial insignificant decline[ baseline therapy, after 1 week, after 3 months, and after 1 yr (mean ± sem), 2.37 ± 0.24, 2.20 ± 0.21 (P = NS), 2.51 ± 0.23 (P= NS), and 2.76 ± 0.25 (P = 0.01) L/s]. FIF50% correlated significantly with the smallest cross-sectional tracheal area (baseline, 1 week, and 1 yr: r = 0.74; P < 0.001, r = 0.63; P < 0.005, and r = 0.46; P < 0.05). Changes in tracheal anatomy did not correlate with changes in either lung dynamics or goiter size. In conclusion, very large goiters can be reduced by a third, on the average, with high dose 131I therapy without any initial clinically significant tracheal compression. Tracheal cross-sectional area as well as pulmonary inspiratory capacity improve. No serious adverse effects are seen.