Self-skin Examination for Skin Cancer Detection in High-risk Populations: A Diagnostic Accuracy Study and...

Aquatic populations experience high cumulative ultraviolet radiation exposure and elevated skin cancer risk. Self-skin examination is widely promoted within cancer education strategies; however, its diagnostic accuracy in high-risk groups remains unclear.

Adults (≥ 18 years) participating in surfing or outdoor swimming (≥ 1 h/week) underwent full-body skin examination by an accredited skin cancer doctor. Prior to examination, participants identified any lesion(s) of concern, reflecting real-world self-detection. Suspicious lesions were biopsied or excised, with histopathology as the reference standard. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated.

Among 191 participants (123 surfers, 68 swimmers), 50.8% were diagnosed with at least one skin cancer. Basal cell carcinoma was most common (n = 42), followed by melanoma (n = 26), SCC in situ (n = 17), and SCC (n = 3). Self-detection demonstrated modest sensitivity for BCC (69.0%) and melanoma (61.5%), with low specificity (~ 44-47%) and consistently low PPVs (< 30%). False-negative rates were substantial for BCC (31.0%), SCC in situ (41.2%), and melanoma (38.5%), indicating that many cancers were not self-recognized.

Self-skin examination demonstrated limited diagnostic accuracy in high-risk aquatic populations. From a cancer education perspective, these findings suggest that self-examination may promote awareness but does not reliably support accurate lesion identification. Clinician-performed full-body skin examination remains essential for early detection. Cancer education for surfers and outdoor swimmers should therefore use self-examination to increase risk awareness and promote timely help-seeking, while emphasizing that the absence of a self-identified lesion does not exclude skin cancer.