"Microneedles in breast cancer therapy: navigating treatment innovation amid biological and technological challenges"

Breast cancer remains a leading cause of cancer-related morbidity and mortality worldwide, with conventional treatments frequently limited by systemic toxicity, multidrug resistance, and high recurrence rates, particularly in triple-negative and metastatic subtypes. Microneedle (MN)- based drug delivery systems have emerged as a minimally invasive platform that bypasses the stratum corneum to enable targeted transdermal and intradermal delivery of chemotherapeutics, nanocarriers, and immunotherapeutics, with reduced systemic exposure. This review critically examines the design principles, fabrication materials, and functional types of microneedles (MNs) as applied to breast cancer therapy. The integration of MNs with nanocarriers, immunotherapy, and stimuli-responsive materials to improve tumor penetration, remodel the immunosuppressive tumor microenvironment, and amplify anticancer immune responses is discussed, along with key biological, safety, and regulatory challenges relevant to clinical translation. Microneedles offer great promise as a versatile platform to increase the effectiveness and safety of breast cancer therapies.