Figure 1.

Study flow diagram. Following the guidelines of the Cochrane Handbook for Systematic Reviews of Intervention [25], it was performed a sensitive search in the online databases to identify the studies that examined associations between different nanoformulation and head and neck cancer (HNC) treatment. This systematic review searched for relevant studies considering publications up to June 2020. The chart diagram was reproduced from Moher, Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement; published by PLoS Med., 2009 [26].