MKI67 and thyroid tumor: SIRI levels differed significantly across the following clinicopathological subgroups (all P < 0.05): tumors >1 cm vs. ≤ 1 cm in maximum tumor diameter, high KI67 index (≥3%) vs. low KI67 (<3%), LNM-positive vs. LNM-negative, capsular invasion vs. non-invasion, and bilateral vs. unilateral thyroid tumors.