Total estrogens were positively associated with ER-/PR- breast cancer (OR associated with a doubling of total estrogens 1.16; 95% CI 1.02–1.32), as were metabolites in the 16-pathway including estriol [OR 1.11; 95% CI 1.01–1.22], 16-epiestriol [OR 1.11; 95% CI 1.01–1.21)], 17-epiestriol [OR 1.06; 95% CI 1.01–1.13], and total 16-hydroxylation pathway metabolites [OR 1.11; 95% CI 1.00–1.24]. The gene discussed is ESR1; the disease is breast cancer.