Clinical Characteristics in Early Childhood Associated with a Nevus-Prone Phenotype in Adults from Tropical Australia: Two Decades of Follow-Up of the Townsville Preschool Cohort Study

Abstract

Having numerous melanocytic nevi increases melanoma risk. Few studies have enumerated nevi in children and re-examined them as adults. We aimed to determine if childhood nevus-counts predict nevus-prone adults, and further explore the relevance of host-factors and sun-exposure. Fifty-one Caucasian residents of Townsville (19.16° S, Queensland, Australia) had full-body nevus-counts aged 1–6 and 21–31 years-old. Sun-exposure was determined from questionnaires. Children in the upper-quartile of nevus-counts acquired nevi more rapidly than those in the bottom-quartile (13.3 versus 4.7 nevi/year; p < 0.0005). Children sunburnt before 7 years-old acquired more incident nevi by adulthood (238 versus 126, p = 0.003) particularly if sunburn was severe (321 versus 157.5, p = 0.003) or erythema occurred annually (380 versus 132, p = 0.008). Fair-skinned, freckled children with some nevi ≥ 3 mm, solar lentigines, or a family history of melanoma acquired more incident nevi than children without these attributes. Nevus-prone adults exhibit distinguishing features earlier in life (<7 years-old in Queensland) than has been shown previously. In addition to intervening with sun-protection counselling early enough to reduce risk, being able to reliably triage children into high- and low melanoma-risk groups may inform more efficacious and cost-effective targeted-screening in melanoma-prone populations. Further longitudinal research is needed to confirm that these attributes can reliably separate risk-groups.

Evaluating the effect of tanning response to sun exposure on the risk of skin diseases through Mendelian randomization

“…Seborrhoeic keratosis is reported to associate with sun exposure and tanning (Del Rosso, 2017). Sunlights have some influence on the occurrence of Melanocytic naevi (Barsoum and Harrison, 2020). The common naevi distribution pattern over the skin is consistent with the sun exposure habit (Carli et al, 1998).…”

Sun-Protective Clothing Worn Regularly during Early Childhood Reduces the Number of New Melanocytic Nevi: The North Queensland Sun-Safe Clothing Cluster Randomized Controlled Trial

“…Infants and children are particularly vulnerable to the effects of excessive sun exposure [ 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ], and UVR-related changes in an infant’s skin have been shown to begin accumulating from their first summer [ 31 ]. Migrants relocating to UVR-intense climates after ten years of age develop fewer MN and are less likely to develop melanoma as adults than native-born residents or migrants who arrive earlier in life [ 24 , 32 ], suggesting that childhood is a critical time for the influence of sun exposure in MN development [ 24 , 25 , 26 , 27 , 28 , 29 , 30 , 32 , 33 , 34 , 35 ]. Children raised in NQ acquire common MN, large MN, and atypical MN earlier and in higher numbers (up to 252 common MN by age six) than children raised in less intense solar UVR environments [ 27 , 28 , 29 , 30 , 33 ], putting them at increased risk of developing melanoma in the future [ 5 , 17 , 19 , 20 , 21 , 24 , 32 ].…”

“…Total number of sunburns experienced by these young children since birth was, however, an independent predictor of the presence of MN that were at least five millimeters in diameter by their annual follow-up examination [ 29 ]. More recently, our 20+-year follow-up of this pediatric cohort found that the rate of acquisition of new MN between early childhood and the third decade of life was significantly higher in individuals who had experienced a sunburn before seven years of age, particularly if the sunburn was severe or had occurred annually during early childhood [ 35 ]. Other recent epidemiological studies of MN [ 26 , 34 ], including a cross-sectional analysis of baseline data from the “Study of Nevi in Children” (SONIC) by Satagopan and co-workers [ 34 ], corroborate the findings of earlier studies of MN, demonstrating the importance of sunburn in early life and host factors such as sun sensitivity in their development [ 24 , 28 , 29 ].…”

“…However, MN frequency is similar in older individuals from these contrasting climates, suggesting that early acquisition of MN increases melanoma risk [ 16 , 30 , 45 ]. Because sun exposure is related to MN development during childhood [ 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 32 , 35 , 36 ], and MN count and sun exposure are both risk factors for cutaneous melanoma [ 3 , 4 , 5 , 6 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 24 , 32 , 39 , 40 , 43 , 45 ], MN counts provide a short-term measure of the efficacy of interventions designed to reduce sun exposure and subsequent melanoma risk [ 46 , 47 , 48 ]. Australia is recognized internationally for its skin cancer prevention programs dating back to the 1980s [ 7 ]; thus, when our randomized controlled trial (RCT) commenced, most (97.8 percent) accredited childcare centers in Queensland already had a written sun protection policy requiring children to use high sun protection factor (SPF) sunscreen and wear a hat at childcare [ 49 ], while protective clothing was underutilized [ 46 ].…”