Menopausal hormone therapy may increase risk for basal cell carcinoma

Menopausal hormone therapy increased risk for basal cell carcinoma, especially among women with an older age at menopause, according to the results of a nationwide cohort study.

These women may require more frequent skin cancer screening, according to the researchers.

Basal cell carcinoma is the most common human malignancy, with over 1 million cases diagnosed per year in the U.S. Although the photosensitizing properties of estrogens have been recognized for some time, little study has been conducted on the association between reproductive factors of exogenous estrogen use and basal cell carcinoma, according to study background.

Thus, Elizabeth K. Cahoon, PhD, of the radiation epidemiology branch of the division of cancer epidemiology and genetics at the NCI, and colleagues sought to assess the relationship between reproductive factors, exogenous estrogen use and first primary basal cell carcinoma in a cohort of 46,100 women — all of whom were cancer free at baseline — from the U.S. Radiologic Technologists Study. Researchers accounted for factors including sun exposure, personal sun sensitivity and lifestyle factors.

Four percent of study participants (n = 1,730; median age, 49 years) has an incident basal cell carcinoma during 10-year follow-up, whereas 44,370 women (median age, 46.9 years) did not.

Basal cell carcinoma development occurred at higher rates among women with fair complexion, light eye and hair color, Celtic or Gaelic ancestry, and high lifetime ambient UVR exposure.

Increased basal cell carcinoma risk appeared associated with late age at menopause (HR for age ≥ 55 years vs. 50-54 years = 1.5; 95% CI, 1.04-2.17) and ever-use of menopausal hormone therapy (HR = 1.16; 95% CI, 1.03-1.3).

The greatest risk for basal cell carcinoma occurred among women who reported natural menopause and who received menopausal hormone therapy for 10 or more years, compared with women who never received menopausal hormone therapy (HR = 1.97; 95% CI, 1.35-2.87).

The researchers did not observe an association between basal cell carcinoma risk and age at menarche, parity, age at first live birth, infertility, use of diethylstilbestrol by participant’s mother, age at hysterectomy or use of oral contraceptives.

The researchers acknowledged self-reporting of data as a potential study limitation; however, they surmised that because the study population was comprised of medical professionals, women included in the study may have been able to more accurately report their medical histories than lay women.

The researchers further acknowledged that they did not have data available about specific doses of menopausal hormone therapy or oral contraceptives.

“Because, to our knowledge, this is the first comprehensive examination of basal cell carcinoma risk with reproductive factors and exogenous estrogen use, our findings need to be replicated in other cohorts before strong conclusions can be drawn,” Cahoon and colleagues wrote. “Future studies could collect more detailed information on medication use, ask participants about photosensitivity reactions, and collect biomarkers of female sex hormones in relation to risk for basal cell carcinoma.” – by Cameron Kelsall

Disclosure: The researchers report no relevant financial disclosures.