Combination Therapy in Cancer Treatment: The Role of Quercetin as an Adjuvant and the Integration of Nanotechnology for Enhanced Efficacy and Reduced Resistance

Quercetin is a flavonoid that comes from natural compounds found in our diet. Research studies have show that quercetin exhibits numerous biological effects, including anti-inflammatory, anti-oxidation, and anti-cancer properties. A systematic search of relevant studies published since 2019 was conducted across major databases, including Science Direct, MDPI, and Frontiers. Experimental evidence from in vivo and in vitro studies have demonstrated quercetin exerts anti-tumor effects through mechanisms such as inhibition of cell cycle progression, induction of apoptosis and suppression of angiogenesis. Additionally, this review discusses the clinical implications of quercetin used as an adjuvant and explores the emerging strategy of combining quercetin with nanoparticles to enhance its bioavailability and therapeutic efficacy. The findings suggest that quercetin, in combination with nanotechnology and anti-cancer medications, holds promise as a valuable adjunct to conventional cancer treatments, warranting further clinical investigation.