*3.1. Observational Studies and Reviews*

A limited number of observational studies and reviews are available on the topic; the majority suggests that adjuvant surgery in selected patients may be useful to improve treatment outcomes [2,15–27]. However, the strength of the conclusions from these studies is somewhat limited by the risk of bias related to the variability of the centres' procedures, patients' profiles, treatment regimens, timing and types of surgical procedures, and it is difficult, if not impossible, to identify homogenous patients to compare among studies.
