Cancers are diverse and often resistant to therapeutic strategies. Gene therapy has yet to meet the promise of a breakthrough in cancer therapy. There are several barriers to overcome in cancer gene therapy. One of the biggest challenges is the design of appropriate vectors. Numerous viral and non-viral methods for gene transfer have been developed for human gene therapy, but both viral and non-viral vectors have limitations and advantages. In this review article, recent improvements in the development of non-viral vectors for delivering gene therapy for the treatment of cancer will be discussed.