Comparative assessment of early mortality risk upon immune checkpoint inhibitors alone or in combination with other agents across solid malignancies: a systematic review and meta-analysis

•This meta-analysis quantifies excess of early mortality upon first-line immunotherapy in solid tumors.•Early mortality risk increases with immunotherapy alone versus other treatments.•Neither PD-L1 levels nor class of immune checkpoint inhibitors predict early mortality.•Gastric and urothelial carcinoma are at higher risk of early mortality upon immunotherapy.•Immunotherapy combination strategies can prevent early mortality.