|The complement system comprises a set of essential molecules that bridge the innate and adaptive immune responses. Research has focused on how the complement system`s destructive mechanism could potentially be harnessed for cancer treatment. However, cancer subverts the complement system to avoid immunosurveillance. In addition, a complement-triggered biological mechanism that contributes to cancer growth has been identified. Thus, drugs should be designed to homeostatically maintain a normal concentration of complement. This review explores three types of complement-related anti-cancer drugs: therapeutic antibodies, complement inhibitory drugs, and anti-complement regulatory drugs.