Animal studies show that antifungal agents fluconazole and itraconazole significantly reduce tumor metastasis, highlighting Candida albicans’ potential role in breast cancer metastasis.68,69 Some bacteria express β-glucuronidase, which hydrolyzes estradiol glycoside conjugates to release free estradiol, promoting ER+ breast cancer growth.70 This mechanism offers new insights into hormone-dependent breast cancer pathogenesis and suggests therapeutic potential in targeting microbial metabolic pathways. Here, ESR1 is linked to breast cancer.