Second outcome: OS
Seven articles about SUVmax measurement of tumor tissue were included in the study.11, 13, 14, 18, 19, 24, 25For moderate heterogeneity (I2 = 36.2%, P = 0.151), the fixed-effects model was applied when pooling HR. The combined HR was 2.582 (95% CI 1.936-3.443, P <0.001), which meant patients with high SUVmax had a shorter survival time than those with low SUVmax (Figure 3A) . Begg’s funnel plot and Egger’s test indicated no publication bias (P = 0.113), and sensitivity analysis showed that the analysis was relatively stable(Figure 3B-C) .
Two articles about primary tumor SUVmean were included in the study.14, 20 For no heterogeneity (I2 = 0.0%, P = 0.893), the fixed-effects model was applied when pooling HR. The synthesized results showed that patients with high SUVmean had a shorter survival time than those with low SUVmean, but there was no statistical significance (HR = 1.523, 95% CI = 0.764–3.038, P = 0.232)(Figure S4A) . Because of the limited data, publication bias and sensitivity analysis were not performed.
Two articles about TLG measurement of tumor tissue were included in the study.14, 20 In the absence of heterogeneity (I2 = 0.0%, P = 0.672), the fixed-effects model was applied when pooling HR. The synthesized results showed that patients with high TLG had a shorter survival time than those with low TLG, but the result had no statistical significance (HR = 1.371, 95% CI = 0.681-2.759, P = 0.377) (Figure S4B) . Because of the limited data, publication bias and sensitivity analysis were not performed.
Two articles about nodal SUVmax were included in the study.19, 22 For no heterogeneity (I2 = 54.1%, P = 0.140), the fixed-effects model was applied when pooling HR. The synthesized results showed that patients with high nodal SUVmax had a shorter survival time than those with low nodal SUVmax (HR = 2.095, 95% CI = 2.027-2.166, P <0.001) (Figure S4C) . Because of the limited data, publication bias and sensitivity analysis were not performed.