Endometriosis and the risk of skin cancer: a prospective cohort study

Endometriosis has been associated with an increased risk of skin melanoma. However, associations with other skin cancer types and how they compare with melanoma are unclear. Our objective was to prospectively investigate the relationships between endometriosis and risk of non-melanoma and melanoma skin cancers.

E3N is a prospective cohort of 98,995 French women aged 40-65 years in 1990. Data on surgically confirmed endometriosis and skin cancer diagnoses were collected every 2-3 years through self-report, with skin cancer cases confirmed through pathology reports. Hazard Ratios (HR) and 95% confidence intervals (CIs) were calculated using Cox regression models.

Between 1990 and 2008, 535 melanoma, 247 squamous-cell carcinoma (SCC), and 1,712 basal-cell carcinoma (BCC) cases were ascertained. Endometriosis was associated with an increased overall risk of skin cancer (HR 1.28, 95% CI 1.05-1.55). When considering skin cancer type, endometriosis was associated with melanoma risk (HR 1.64, 95% CI 1.15-2.35), but not with SCC (HR 1.21, 95% CI 0.62-2.36) or BCC (HR 1.16, 95% CI 0.91-1.48) (non-melanoma skin cancers combined: HR 1.17, 95% CI 0.93-1.46), although no heterogeneity was detected across skin cancer types (Phomogeneity = 0.13).

These data support an association between a personal history of endometriosis and the risk of skin cancer and suggest that the association is strongest for melanoma.