Thyroid nodules enlarge with time (II)
(March 2003)
The background of
the study. There have been few long-term studies of patients
with benign thyroid nodules, in particular studies in which changes
in nodule volume were evaluated as a function of the cystic content
of the nodule. In this study patients with benign thyroid nodules
were reevaluated months to years after the first evaluation and
biopsy.
How the study was done. The study
subjects were 700 patients who had 854 biopsy-proven benign thyroid
nodules 1 cm or larger in diameter when first evaluated. The patients
were asked to return in 9 to 12 months for repeat ultrasonography
and possible biopsy. Among them, 268 patients (38 percent), who
had 330 nodules (39 percent), returned an average of 20 months later.
The ultrasound images at both times were compared; nodules were
considered to have enlarged if the maximal diameter had increased
by >50 percent or by ≥3 mm, or if the volume had increased
by ≥15 percent; the latter was the primary end point of the
study.
The results of the study. As measured
by a ≥15 percent increase in nodule volume, 129 nodules (39
percent) had enlarged. In contrast, based on a >50 percent increase
in maximal diameter, 14 nodules (4 percent) enlarged, and based
on a ≥3 mm increase in diameter, 86 nodules (26 percent) had
enlarged. Nodules that were >50 percent cystic when first examined
were less likely to enlarge than those with lesser cystic content.
The likelihood of enlargement was not related to age, sex, initial
serum thyrotropin concentration, or thyroxine therapy, but was related
to duration between studies. The calculated time to a ≥15
percent increase in nodule volume in half the patients was 35 months;
the proportion of patients having this increase in volume was 53
percent at three years and 89 percent at five years.
Sixty-one of the 268 patients (23 percent) had a second biopsy.
The volume of these nodules had increased by an average of 69 percent,
as compared with a 14 percent increase in nodules not biopsied again.
The conclusions of the study. Benign
thyroid nodules, especially mostly solid nodules, grow slowly.
The original article. Alexander
EK, Hurwitz S, Heering JP, Benson CB, Frates MC, Doubilet PM, Cibas
ES, Larsen PR, Marqusee E. Natural history of benign solid and cystic
thyroid nodules. Ann Intern Med 2003;138:315-8.
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