Efficacy and Safety of Huaier Granule as an Adjuvant Therapy for Cancer: An Overview of Systematic Reviews and Meta-Analyses

INTRODUCTION: In China, Huaier granule (HG) is widely applied to tumor adjuvant therapy. However, systematic reviews (SRs) or meta-analyses (MAs) published continuously failed to reach a consensus, without convincing evidence. An overview should be conducted to summarize the evidence-based progress and try to provide some value references for relative research and clinical practice in the future. METHODS: From inception to October 2021, 8 databases in English and Chinese were searched. SRs/MAs meeting the inclusion and exclusion criteria were included. Relevant criteria were used to evaluate SRs/MAs including methodological quality, reporting quality, risk of bias, and evidence quality of effect and safety. RESULTS: The short-term effect, long-term effect, and safety in 6 included SRs/MAs were assessed in this overview according to quantitative synthesis. Results assessed by AMSTAR-2, PRISMA, and ROBIS were generally unsatisfactory with the main problems on registration or protocol, a search of grey literature, a list of excluded studies, bias of each synthetic result, and inadequate report of search strategy and synthesis methods. Additionally, 28 items were assessed as moderate quality while 12 items were low-quality and 6 items were very low-quality in GRADE. Risk of bias was the main downgrading factor. CONCLUSION: HG may be a promising adjuvant therapy for cancer. However, high-quality SRs/MAs and RCTs should be conducted to provide sufficient evidence so as to draw a definitive conclusion.