The rate of increase in the numbers of primary sporadic basal cell carcinomas during follow up is associated with age at first presentation.

Basal cell carcinoma (BCC) patients demonstrate marked variation in tumour numbers and site. Previous studies also show an association between age at first BCC presentation and development of BCC on the trunk. In this study we have investigated the association between age at first presentation and the rate of development of truncal and non-truncal tumours in 747 patients with BCC. We used negative binomial regression analysis to show that increasing age at first presentation was associated with an increased rate of BCC development (rate ratio 1.01/year, 95% CI 1.01-1.02, P < 0.001). In particular, development of tumours was greater in cases aged 60.0-69.9, 70.0-79.9 and 80.0-89.9 years than in those 40.0-49.9 years (P = 0.05, 0.01 and 0.039, respectively). While few cases aged over 70 years of age first present with a truncal BCC, the numbers of BCC/year were greater than in those with a head/neck BCC. The data suggest different genetic factors mediate the appearance of BCC in patients of different ages particularly those aged above and below 60 years.