We have developed a “targeting” treatment based on the fact that hyaluronic acid specifically combines with cell surface receptors, glycoprotein CD44 (cluster of differentiation 44) and RHAMM (receptor for hyaluronan mediated motility), which are highly expressed in certain cancer cells. We then select anti-cancer drugs, and conjugate them with hyaluronic acid. Using hyaluronic acid as a carrier, we develop hyaluronic acid conjugated drugs targeted to cancer cells.