The association between pregnancy timing and cumulative exposure on survival in melanoma

Background — As melanoma is common among young women, the impact of pregnancy on melanoma prognosis is of interest.

Objective — The purpose of this study was to examine the association between pregnancy and survival in female melanoma patients of childbearing age.

Methods — We performed a population-level, retrospective cohort study of women of childbearing age (18–45 years) diagnosed with melanoma from 2007 to 2017 using administrative data from Ontario, Canada. Patients were categorized according to pregnancy status (i.e. pregnancy before [conception from 60 to 13 months prior to melanoma], pregnancy-associated [conception 12 months prior to and after], and pregnancy after [conception 12 months after] melanoma). Cox models were used to examine melanoma-specific survival (MSS) and overall survival (OS) associated with pregnancy status.

Results — Of 1312 women with melanoma, most did not experience pregnancy (84.1%), with 7.6% experiencing a pregnancy-associated melanoma and 8.2% experiencing a pregnancy after melanoma. Pregnancy before melanoma occurred in 18.1% of patients. Pregnancy before (hazard ratio [HR] 0.67, 95% confidence interval [CI] 0.35–1.28), associated (HR 1.15, 95% CI 0.45–2.97), and after melanoma (HR 0.39, 95% CI 0.13–1.11) was not associated with a difference in MSS compared with those who did not experience a pregnancy during these time periods. Pregnancy status was also not associated with a difference in OS (p > 0.05). Cumulative weeks pregnant were not associated with a difference in MSS (4-week HR 0.99, 95% CI 0.92–1.07) or OS (4-week HR 1.00, 95% CI 0.94–1.06).

Conclusions — In this population-level analysis of female melanoma patients of childbearing age, pregnancy was not associated with a difference in survival, suggesting that pregnancy is not associated with a worse melanoma prognosis.