Abstract
Naevus count is the strongest risk factor for melanoma. Body Mass Index (BMI) has been linked to melanoma risk. In this study, we investigate the link between naevus count and height, weight and bone mineral density (BMD) in the TwinsUK cohort (N = 2119). In addition we adjusted for leucocyte telomere length (LTL) as LTL is linked to both BMD and naevus count. Naevus count was positively associated with height (p = 0.001) but not with weight (p = 0.187) despite adjusting for age and twin relatedness. This suggests that the previously reported melanoma association with BMI may be explained by height alone. Further adjustment for LTL did not affect the significance of the association between height and naevus count so LTL does not fully explain these results. BMD was associated with naevus count at the spine (coeff 18.9, p = 0.01), hip (coeff = 18.9, p = 0.03) and forearm (coeff = 32.7, p = 0.06) despite adjusting for age, twin relatedness, weight, height and LTL. This large study in healthy individuals shows that growth via height, probably in early life, and bone mass are risk factors for melanoma via increased naevus count. The link between these two phenotypes may possibly be explained by telomere biology, differentiation genes from the neural crests but also other yet unknown factors which may influence both bones and melanocytes biology.