Gene profiling can distinguish between papillary
and follicular thyroid carcinomas and benign thyroid nodules
The background of the study. Most papillary thyroid
carcinomas can be identified by fine-needle aspiration biopsy, but
follicular carcinomas and follicular variants of papillary carcinoma
cannot be distinguished from benign nodules. This study was undertaken
to determine if benign thyroid nodules could be distinguished from
thyroid carcinomas by gene profiling.
How the study was done. Abnormal thyroid tissue
was obtained at surgery from 59 patients (50 women, 9 men; mean
age, 51 years) with a thyroid nodule. The nodule was a follicular
adenoma or hyperplastic nodule in 26 patients, a papillary carcinoma
in 11, a follicular variant of papillary carcinoma in 13, and a
follicular carcinoma in 11.
RNA was extracted from the tumors, amplified, and hybridized to
627 genes on a gene chip. After staining, the chips were scanned
to detect hybridization signals. The results were analyzed by cluster
analysis, which led to grouping of genes according to whether they
were more than two times underexpressed or overexpressed.
The results of the study. As a test set, 21 benign
nodules and 24 papillary (including follicular variants) and follicular
carcinomas were studied. Among the 627 genes, 61 were overexpressed
and 72 were underexpressed in the papillary and follicular carcinomas,
as compared with the benign nodules. The profile of one follicular
adenoma was similar to that of the carcinomas, and the profile of
one follicular variant of papillary carcinoma was similar to that
of the benign nodules. Addition of the results from five benign
nodules and nine carcinomas resulted in two similar, distinct groups;
the profile of one follicular adenoma was similar to that of the
carcinomas, and the profile of three follicular variants of papillary
carcinoma was similar to that of the benign nodules. The sensitivity
was 91 percent and the specificity was 96 percent for the detection
The conclusions of the study. Different genes
are activated and inactivated in benign thyroid nodules and papillary
and follicular thyroid carcinomas, and the differences can be detected
by gene profiling.
The original article. Finley DJ, Zhu B, Barden
CB, Fahey TJ III. Discrimination of benign and malignant thyroid
nodules by molecular profiling. Ann Surg 2004;240:425-37.