Analysis of 26 occult thyroid carcinomas, which are small papillary carcinomas with clinically apparent node metastases but are often microscopic or overlooked by ultrasonograms, determined that RET/PTC activation is found in 42% (11/26) of samples analyzed, suggesting that RET/PTC activity contributes to early papillary thyroid carcinogenesis (103). This evidence concerns the gene CCDC6 and papillary carcinoma.