<i>ras</i> Mutations Are Associated With Aggressive Tumor Phenotypes and Poor Prognosis in Thyroid Cancer

TLDR

The study investigates whether ras mutations correlate with clinicopathologic features in thyroid carcinomas of follicular cell origin. The authors screened 125 thyroid carcinoma specimens for H‑, K‑, and N‑ras mutations using PCR‑SSCP followed by DNA sequencing. RAS mutations were significantly more frequent in poorly or undifferentiated thyroid carcinomas and were associated with markedly higher mortality, making them an independent marker of aggressive disease and poor prognosis.

Abstract

Purpose: ras oncogenic activation has long been demonstrated in thyroid carcinomas of follicular cell derivation, but no consistent relationship has been shown between mutations and clinicopathologic features. Materials and Methods: We analyzed H-, K-, and N-ras mutations by polymerase chain reaction–single-strand conformational polymorphism followed by DNA sequencing in 125 thyroid carcinoma specimens from 107 patients, to include tumors covering the entire spectrum of thyroid tumor differentiation. Results: Mutations were identified in four (8.2%) of 49 well-differentiated carcinomas (WDCs; two [6.7%] of 30 of the tumors were papillary carcinomas, two [10.5%] of 19 of them were follicular carcinomas), in 16 (55.2%) of 29 poorly differentiated carcinomas (PDCs), and in 15 (51.7%) of 29 undifferentiated carcinomas, with a significant association between ras mutation and poorly or undifferentiated tumors (P &lt; .001). Twenty-six (74.3%) of 35 patients with ras-mutated tumors died as a result of disease as opposed to 23 (31.9%) of 72 patients with tumors lacking the mutations. Among patients with differentiated thyroid carcinomas (WDC and PDC), 11 (55.0%) of 20 patients with mutated tumors died as a result of disease as opposed to nine (15.5%) of 58 patients with wild-type ras tumors, and the correlation was independent of tumor differentiation and stage (P = .016). K-ras codon 13 mutations (all with G-A nucleotide transitions resulting in Gly&gt;Asp substitution) and single activating mutations in any of the ras genes were also independent predictors of poor survival in differentiated thyroid carcinomas (P = .027 and P = .007, respectively). Conclusion: These findings demonstrate that ras mutations are a marker for aggressive cancer behavior and indicate a possible role of ras genotyping to identify thyroid carcinoma subsets associated with poor prognosis.