In this chapter, we outline the steps for designing and conducting a rigorous systematic review and meta-analysis, focusing on the efficacy of immune checkpoint inhibitors (ICIs) in elderly patients. ICIs have improved survival rates in advanced cancers, yet their effectiveness in older populations remains unclear. We detail the essential processes involved in both systematic reviews and meta-analyses. We can evaluate the efficacy of ICIs in elderly patients with advanced cancer, examining outcomes such as overall survival and progression-free survival.