Exogenous Estrogen in the Development of Head and Neck Cancer.

IMPORTANCE: Sex differences in head and neck cancer (HNC) incidence suggest a potential contribution of sex hormones.

OBJECTIVE: To assess the role of exogenous estrogen exposure in the development of HNC in female patients.

DESIGN, SETTINGS, AND PARTICIPANTS: This large multicenter cohort study using clinical records from the TriNetX real-world database included 20 years of data (through May 31, 2023) from 87 health care organizations. The TriNetX database was searched for medical records for female patients with and without exogenous estrogen exposure according to their chronological age. Cohort 1 included 731 366 female patients aged 18 to 45 years old with regular oral contraceptive (OC) intake and cohort 2 included 3 886 568 patients in the same age group who did not use OC. Cohort 3 comprised 135 875 female patients at least 50 years old receiving hormone replacement therapy (HRT), whereas cohort 4 included 5 875 270 patients at least 50 years old without HRT. Propensity score matching was performed for the confounders age, alcohol dependence, and nicotine dependence. Data analyses were performed in May 2023.

MAIN OUTCOME AND MEASURES: Diagnosis of HNC (International Statistical Classification of Diseases and Related Health Problems, Tenth Revision: C00-C14), and after propensity score matching (1:1 nearest-neighbor greedy matching), a risk analysis to investigate risk differences and risk ratios (RRs) with a 95% CI.

RESULTS: Among the 718 101 female patients in each of cohorts 1 and 2 (mean [SD] age at diagnosis, 25.9 [6.7] years), those with OC intake had a higher risk of an HNC diagnosis (RR, 1.47; 95% CI, 1.21-1.78) than those without OC use. Among the 131 835 female patients in each of cohorts 3 and 4 (mean [SD] age, 67.9 [12.0] years), those with postmenopausal HRT intake had a lower risk of an HNC diagnosis (RR, 0.77; 95% CI, 0.64-0.92) than those without HRT use.

CONCLUSIONS AND RELEVANCE: The findings of this cohort study illustrate a positive association between OC and a negative association between HRT and the development of HNC in female patients. Given the limitations of the TriNetX database, future research should include detailed information on the intake of OC and HRT and reproductive health information (eg, age at menarche/menopause, number of pregnancies) to more accurately define the strength and direction of the possible association between exogeneous estrogen exposure and the development of HNC in female patients.