Actinic Keratosis (AK), also known as solar keratosis, is characterized by dysplastic keratinocytic lesions confined to the epidermis. It is triggered by chronic sun damage in approximately 75 % of patients and is considered an early warning sign of skin cancer. In addition to long-term sun exposure, environmental factors such as ionizing radiation, thermal radiation, asphalt, and coal tar products can also contribute to the development of AK. Individual factors including age, sex, skin type, personal or family history of skin tumors, and outdoor work history also play a role in its pathogenesis. The specific etiology of individual AK lesions is not well understood. However, studies have shown that AK can occasionally progress into invasive squamous cell carcinoma (SCC), with an estimated occurrence probability ranging from 0.025 % to 16.000 % per year, and an average of 0–10 % in statistical analysis [1]. Clinically, AK typically enlarges slowly and often presents as macules, papules, or hyperkeratotic plaques with an erythematous background on the skin [2]. It is more commonly observed in middle-aged and elderly individuals, particularly those over 40 years old. Predilection sites include daily photo-exposed areas such as the face, scalp, neck, forearms, and hands. In China, the prevalence of AK is approximately 0.52 % in patients with a mean age of 69.8 ± 11.8 years, which is relatively lower than the prevalence in Western countries (ranging from 4.5 % to 60 % in Caucasian population aged 40 years and above) [2,3]. With the aging society, AK has become increasingly common, highlighting the significance of timely and appropriate treatment based on individual patient's skin lesions rather than the specific cause of the disease. The therapy for AK should consider various factors including efficacy, convenience, economy, and aesthetics.

In 1999, FDA approved 20 % ALA-PDT for the treatment of non-hyperkeratotic AK, accounting for 20 % of the cases [4]. Currently, in China, ALA-PDT is widely recommended and considered an effective therapy for AK, particularly for patients with head and facial lesions, multiple or large area lesions, and special situ lesions like lips, eyelids, ears, and high cosmetic requirements [5]. PDT treatment involves a cold photochemical reaction that relies on three elements: oxygen, photosensitizer, and appropriate light [6]. 5-ALA is a commonly used photosensitizer that acts as a precursor drug with no inherent photosensitive activity. Once applied and absorbed by cells with high metabolic activity, it is converted into the endogenous photosensitive substance protoporphyrin IX (PpIX) with the help of various heme synthetases in and outside the mitochondria [7]. Subsequently, upon activation by appropriate light (generally red light), PpIX accumulates and generates a large amount of reactive oxygen species (ROS) with cytotoxic effects in situ [8]. Through direct and indirect tissue and cellular damage, ALA-PDT successfully achieves the goal of treating AK lesions.

In clinical practice, the satisfaction level of AK patients who completed ALA-PDT treatment was not optimal, despite ALA-PDT being the recommended therapy for these patients. Various factors contributed to this, including high costs, adverse effects, and the overall health status of the patients. Previously, there was limited research on the factors that influenced patients’ choice of ALA-PDT therapy. To address this gap, we conducted a retrospective study on AK patients at our hospital over the past two years. The aim of the study was to explore the clinical effectiveness of ALA-PDT treatment for AK lesions and identify the factors that limit patients’ choice of PDT therapy.