RET and thyroid gland papillary carcinoma: Interestingly, a higher percentage of RET exon-8 fMTC patients carried a second malignancy either at diagnosis or at follow-up (25.5% vs 6.3%, P = 0.009, Pearson’s χ2): of the RET exon 8 carriers, 9/51 (17.6%) had papillary thyroid cancer (PTC) and another 4/51 (7.8%) had other malignancies (lung, renal, unknown primary tumor, breast); thus, in 69% of the cases, the second malignancy was PTC.