Do perinatal and early life exposures influence the risk of malignant melanoma? A Northern Ireland birth cohort analysis.

Aim: Intrauterine, early life and maternal exposures may have important consequences for cancer development in later life. The aim of this study was to examine perinatal and birth characteristics with respect to Cutaneous malignant melanoma (CMM) risk.
Methods: The Northern Ireland Child Health System database was used to examine gestational age adjusted birth weight, infant feeding practices, parental age and socioeconomic factors at birth in relation to CMM risk amongst 447,663 infants delivered between January 1971 and December 1986. Follow-up of histologically verified CMM cases was undertaken from the beginning of 1993 to 31st December 2007. Multivariable adjusted unconditional logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CI) of CMM risk.
Results: A total of 276 CMM cases and 440,336 controls contributed to the final analysis. In reference to normal (gestational age-adjusted) weight babies, those heaviest at birth were twice as likely to develop CMM OR 2.4 (95% CI 1.1-5.1). Inverse associations with CMM risk were observed with younger (<25 years) parental age at birth and both a higher birth order and greater household density OR 0.61 (95% CI 0.37-0.99) and OR 0.56 (95% CI 0.30-1.0) respectively.
Conclusion: This large study of early onset melanoma supports a positive association with higher birth weight (imperatively gestational age adjusted) and CMM risk which may be related to factors which drive intrauterine foetal growth. Strong inverse associations observed with higher birth order and household density suggest that early-life immune modulation may confer protection; findings which warrant further investigation in prospective analyses.
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