Cutaneous squamous cell carcinoma (SCC) is the second most common skin cancer. Surgery remains the main stay of treatment, but some patients are not eligible for surgery and, more importantly, lesions at critical sites need nonsurgical approaches for tissue preservation. In this context, photodynamic therapy (PDT) has been extensively studied as noninvasive or minimally invasive treatment, and studies have shown promising results in terms of safety, efficacy, and cosmetic outcome. Also, studies have proposed different mechanism for its efficacy. However, human studies demonstrating its efficacy are limited in terms of sample size and tumor depth of invasion. Good results are mainly seen in case reports of microinvasive SCC, which is defined as SCC limited to papillary dermis. This inadequacy is due to inadequate penetration of topically applied photosensitizers through keratinized tumor surfaces. To overcome these hurdles, pretreatment with lasers or microneedles and encapsulation of photosensitizers into nanoparticles have been tried. Hence, the present article will discuss studies that have demonstrated the efficacy and safety of PDT for cutaneous SCC, studies that have postulated the mechanism of action of PDT, agents that have been used as PDT enhancers, and finally, the recent use of adjuvant therapy in combination with PDT.

皮肤鳞状细胞癌（SCC）是第二常见的皮肤癌。手术仍然是治疗的主要手段，但是一些患者不适合手术，更重要的是，关键部位的病变需要采用非手术方法来保存组织。在这种情况下，光动力疗法（PDT）已作为无创或微创治疗得到了广泛的研究，研究显示出在安全性，功效和美容效果方面令人鼓舞的结果。同样，研究提出了不同的功效机制。然而，证明其功效的人体研究在样本量和肿瘤浸润深度方面受到限制。良好的结果主要在微创性SCC的病例报告中看到，SCC被定义为仅限于乳头状真皮的SCC。这种不足是由于局部施用的光敏剂不能充分渗透通过角化的肿瘤表面。为了克服这些障碍，已经尝试了使用激光或微针的预处理以及将光敏剂封装到纳米颗粒中的方法。因此，本文将讨论已证明PDT对皮肤SCC的有效性和安全性的研究，已推测PDT的作用机理的研究，已被用作PDT增强剂的药物，以及最近在辅助治疗中的应用。与PDT结合使用。