Heterogeneity assessment: bias exploration
A risk of bias analysis was performed for all included studies as per
the Cochrane guidelines . Overall, there was a high level of bias due to
the fact that a majority of studies were not randomized or blinded.
Moreover, we assigned scores for each of the domains D1-D7. No study
fulfilled all of these criteria (figure 3). Funnel plots were used to
assess publication bias for all primary and secondary outcomes. There
was no funnel plot asymmetry for the primary outcome late survival
(supplementary figure 3) and tumor relapse at follow-up (supplementary
figure 4).