GNAS and neoplasm: No relationship was found between the average tumour size and KRAS or GNAS mutation (WMD = 0.000, 95 % CI −0.258 to 0.258, P > 0.999, Q = 0.860, I2 = 0.000 and WMD = 0.086, 95 % CI −0.108 to 0.280, P = 0.384, Q = 0.315, I2 = 0.000, respectively).