Fempro 2.5 mg Tablets Fempro contains Letrozole, a non-steroidal inhibitor of the aromatase enzyme. It acts by competitively binding to the heme group of the cytochrome P450 subunit of aromatase, inhibiting the conversion of androgens to estrogens in peripheral tissues. By significantly suppressing serum estrogen levels, it inhibits estrogen-stimulated tumor growth. It is indicated for the treatment of hormone receptor-positive early breast cancer in postmenopausal women, advanced breast cancer in postmenopausal women, and off-label for ovulation induction in fertility treatments.