Radioactive iodine therapy may reduce the
risk of recurrence of papillary and follicular carcinoma after surgery
(November 2004)
The background of the study. Most patients with
papillary or follicular thyroid carcinoma are treated by thyroidectomy.
Radioiodine (I-131) is then given to destroy any remaining normal
thyroid tissue (remnant ablation). This analysis was undertaken
to determine if remnant ablation reduces the mortality or recurrence
rate in patients with thyroid carcinoma.
How the study was done. The literature was searched
to identify studies of patients who had papillary or follicular
thyroid carcinoma, underwent bilateral thyroidectomy, and were treated
with I-131 within 1 year after surgery; who were followed for at
least 5 years; and for whom 10-year data on outcome were reported.
Twenty-three studies met the inclusion criteria.
The results of the study. Seven studies reported
mortality data. One study of 1510 patients found a significant benefit
of I-131 therapy, after adjustment for age, sex, extent of surgery,
and tumor characteristics. There was no benefit of I-131 therapy
in six other studies, in which the 10-year cancer mortality rates
varied from 1.3 to 15 percent. In 20 studies not adjusted statistically
for other variables, the 10-year mortality rates varied from 0 to
23 percent among I-131-treated patients and 0 to 25 percent among
those not treated.
I-131 therapy was associated with a lower risk of local or regional
recurrence in three studies (relative risks, 0.05, 0.3, and 0.4).
The pooled 10-year local and regional recurrence rates were lower
in I-131-treated patients with either papillary or follicular carcinoma
than in those not treated. I-131 therapy also was associated with
a lower risk of distant metastases in the largest study, of 1510
patients. The pooled 10-year rate of distant metastases was lower
in the I-131-treated patients with either papillary or follicular
carcinoma than in those not treated.
The conclusions of the study. In patients with
papillary or follicular carcinoma of the thyroid, I-131 therapy
may reduce the frequency of local recurrence and distant metastases,
but has little effect on mortality.
The original article. Sawka AM, Thephamongkhol
K, Brouwers M, Thabane L, Browman G, Gerstein HC. A systematic review
and metaanalysis of the effectiveness of radioactive iodine remnant
ablation for well-differentiated thyroid cancer. J Clin Endocrinol
Metab 2004;89:3668-76.
|
