Abstract
BACKGROUND: Pregnancy-associated melanoma (PAM) is melanoma diagnosed during pregnancy or the 12 months postpartum. There is long-standing debate regarding the impact of pregnancy on melanoma prognosis. Previous studies have analysed pooled data from PAM diagnoses of all stages, so findings may not reflect outcomes associated with the diagnosis of in situ or localized PAM that are more commonly diagnosed than later stage PAM. OBJECTIVES: To describe the incidence, perinatal and survival outcomes of in situ or localized primary invasive PAM (melanoma stages 0-II). METHODS: A population-based retrospective cohort study in New South Wales (NSW), Australia was performed, comprising women who birthed between 1 January 1994 and 31 December 2013 and their babies, with mortality data available until September 2018. Women were grouped as gestational PAM (diagnosed with early-stage melanoma during pregnancy), postpartum PAM (diagnosed with early-stage melanoma within 1 year postpartum) or control (women who gave birth without a diagnosis of cancer). Perinatal outcomes were compared using generalized estimating equation models and mortality compared using Cox regression, Kaplan-Meier curves and the log-rank test. RESULTS: In total, 1,785,876 pregnancies were identified, including 223 women (228 babies) with gestational PAM and 467 women (478 babies) with postpartum PAM. The incidence of in situ PAM increased 8.7% (95% CI: 4.0-13.5) per year between 2002 and 2013. The incidence of localized primary invasive PAM did not increase between 1994 and 2013. No significant maternal or neonatal morbidities were identified. Sixteen deaths were observed in women diagnosed with localized primary invasive PAM. The mortality rate for women with gestational PAM did not differ significantly from women with postpartum PAM (2.4/1000 person-years vs. 1.6/1000 person-years, p value = 0.394). CONCLUSIONS: Diagnosis of early PAM in pregnancy or postpartum is not associated with significant adverse outcomes for women or their babies. Early diagnosis remains important to ensure appropriate treatment and positive outcomes.