Advances in non-invasive delivery strategies for anti-cancer therapy.

Anti-cancer drugs frequently encounter challenges such as inadequate tumor accumulation and limited therapeutic efficacy, leading to recurrence and adverse effects. Advances in drug delivery systems have been instrumental in addressing these limitations. However, much of the existing research has focused on invasive administration routes, particularly injection, to achieve higher bioavailability. This approach often compromises patient tolerance and compliance, especially in cases requiring long-term and repeated treatment. Consequently, there is growing interest in developing anti-cancer strategies that combine high bioavailability and tumor targeting with non-invasive drug delivery methods. These alternatives, including oral, nasal, pulmonary, buccal mucosal, and transdermal systems, not only aim to improve patient adherence and reduce systemic side effects, but also retain the inherent merits of various formulations, such as enhanced drug delivery efficiency and improved biocompatibility. This review highlights the clinical relevance of non-invasive anti-cancer strategies, outlines the anatomical and physiological barriers of each route, examines their applicability in cancer treatment, and discusses recent advances and design considerations for developing effective and translatable non-invasive delivery systems.