Gene therapy enables direct manipulation of underlying genetic drivers for cancer initiation, progression, and therapeutic resistance, thereby rapidly transforming modern oncology. Various advances in viral and non-viral delivery platforms, as well as genome editing technologies such as CRISPR/Cas9, RNA interference, microRNA modulation, and adoptive immune cell engineering, have given rise to new approaches for more precise and personalized cancer treatment regimens. Ongoing research in multiple cancer types, including breast, lung, colorectal cancers, and hematological malignancies, has shown promising outcomes through gene therapy strategies such as tumor suppressor gene replacement, oncogene silencing, suicide gene therapy, oncolytic virotherapy and CAR-T cell therapy. Continuous improvements in delivery platforms, tumor-specific promoters, and built-in safety switch systems are major research areas to address key barriers, including unwanted immune responses, tumor heterogeneity, and off-target effects. Additionally, combination treatment strategies that integrates immunotherapy with targeted therapies, and gene-based interventions are emerging as powerful combinatorial approaches enabling long-lasting remissions, preventing resistance, and pushing the future towards precision and personalized cancer therapy.