Proportion of Japanese Patients with Multiple Basal Cell Carcinomas: The Effectiveness of Screening

Basal cell carcinoma (BCC) usually occurs as a solitary lesion but occasionally presents as multiple lesions. The proportion of multiple BCCs is 5.9%-7.1% in Asian patients. We conducted BCC screening in April 2021, focusing on the presence or absence of multiple lesions. Patients examined between April 2021 and March 2022 (161 lesions in 136 patients) were classified as the screening group (SG) and those examined between April 2020 and March 2021 (111 lesions in 103 patients) were classified as the non-screening group (NSG). The proportion of patients with multiple BCCs was significantly higher in the SG than in the NSG (15.4% and 6.8%, p = 0.04). We provisionally classified the head and neck gaze region into the 'central region' and 'peripheral region' based on gaze patterns. In the SG, the proportion of lesions in the peripheral region was higher in patients with multiple BCCs (32.6%) than in patients with a solitary BCC (14.8%). We speculate that we missed recognizing tumours in different areas, especially peripheral areas of the head and neck. Our results indicate that the increase in multiple lesion cases through screening occurred owing to more conscious observation of different regions, especially head and neck regions, thereby overcoming human gaze patterns.