Finally, in sporadic MTCs, RET mutation was found to be an indicator of poor prognosis, with an increased risk of both tumour recurrence (OR = 3.01, 95%CI [1.65–5.48], I2 = 41%) and patient death (OR = 2.43, 95%CI [1.06–5.57], I2 = 33%) [55]. This evidence concerns the gene RET and neoplasm.