Innovative theranostic hydrogels for targeted gastrointestinal cancer treatment

Gastrointestinal tumors are the main causes of death among the patients. These tumors are mainly diagnosed in the advanced stages and their response to therapy is unfavorable. In spite of the development of conventional therapeutics including surgery, chemotherapy, radiotherapy and immunotherapy, the treatment of these tumors is still challenging. As a result, the new therapeutics based on (nano)biotechnology have been introduced. Hydrogels are polymeric 3D networks capable of absorbing water to swell with favorable biocompatibility. In spite of application of hydrogels in the treatment of different human diseases, their wide application in cancer therapy has been improved because of their potential in drug and gene delivery, boosting chemotherapy and immunotherapy as well as development of vaccines. The current review focuses on the role of hydrogels in the treatment of gastrointestinal tumors. Hydrogels provide delivery of drugs (both natural or synthetic compounds and their co-delivery) along with gene delivery. Along with delivery, hydrogels stimulate phototherapy (photothermal and photodynamic therapy) in the suppression of these tumors. Besides, the ability of hydrogels for the induction of immune-related cells such as dendritic cells can boost cancer immunotherapy. For more specific cancer therapy, the stimuli-responsive types of hydrogels including thermo- and pH-sensitive hydrogels along with their self-healing ability have improved the site specific drug delivery. Moreover, hydrogels are promising for diagnosis, circulating tumor cell isolation and detection of biomarkers in the gastrointestinal tumors, highlighting their importance in clinic. Hence, hydrogels are diagnostic and therapeutic tools for the gastrointestimal tumors.