RET/NTRK1 rearrangements in thyroid gland tumors of the papillary carcinoma family: Correlation with clinicopathological features

The papillary carcinoma family (PCF) of thyroid tumors includes a wide variety of neoplastic entities regarded as well-differentiated, poorly differentiated, and undifferentiated papillary thyroid carcinomas. Recent studies have established the presence of alternative oncogenic rearrangements of the RET and NTRK1 genes in a consistent fraction (≤50%) of papillary thyroid tumors. RET oncogenic rearrangements are also very frequent (~60%) in Chernobyl radiation-associated papillary thyroid neoplasias, which show an increased aggressiveness in terms of pathological stage at disease onset. These observations prompted us to study the relationship between the presence or absence of RET and NTRK1 oncogenes and the clinicopathological features (age, sex, histopathology, and pTNMC2 staging) of 76 consecutive, non- radiation-related tumors of the PCF. As previously reported, statistical univariate analysis revealed a correlation between the combination of RET and NTRK1 (RET/NTRK1) positivity and young age of patients at diagnosis. In addition, a significant association was found between RET/NTRK1 positivity and locally advanced stage of disease at presentation (pT₄: P <0.015). The multivariate analysis confirmed that RET/NTRK1 activation parallels an unfavorable disease presentation, which may correlate with a less favorable disease outcome. Furthermore, within the PCF, the frequency of RET/NTRK1 positivity was not influenced by the different neoplastic subtypes or the tumor versus degree of differentiation.