Results of second-stage screening for skin cancers in Oita Prefecture, Japan

We performed skin cancer screenings for 2 or 3 days annually from 2006 through 2013 in Oita Prefecture, Japan. Screening of approximately 3000 people in total allowed us to identify and treat several skin cancers, including five cases of malignant melanoma, four of squamous cell carcinoma, 16 of basal cell carcinoma, 11 of Bowen's disease, 17 of actinic keratosis, one of extramammary Paget's disease and one of metastatic breast carcinoma. The sensitivity and specificity for the category defined by an identified lesion associated with risk of cancer and requiring further examination (category C) were 92.7% and 95%, respectively. We cannot estimate the outcome of our skin cancer screenings in terms of cancer mortality because of the small number of subjects examined and the brief follow-up period. However, we did estimate the effectiveness of these screenings in terms of stages or sizes of cancerous lesions. The relative numbers of subjects with malignant melanoma at various clinical stages, identified during skin cancer screenings and during a routine visit to our hospital, were significantly different. We also compared, statistically, the sizes of lesions in Bowen's disease that were found during cancer screenings and during a direct visit to our hospital. The former lesions were smaller than the latter. Our data suggest the benefits of our skin cancer screenings and the importance of campaigns and education to encourage people to visit dermatologists for the detection of skin cancers at an early stage.