In photodynamic therapy, a light-sensitive drug accumulates in cancer cells and is then activated by light, producing cell-killing molecules. Microneedles can help deliver the drug and distribute light more effectively within non-melanoma skin cancer. Image by M. Requena et al. A biodegradable microneedle patch designed to deliver treatment through the skin may also guide and scatter light, potentially allowing photodynamic therapy (PDT) to treat nonmelanoma skin cancers more