What is the mechanism of Letrozole?

Letrozole is a medication primarily used in the treatment of hormonally-responsive breast cancer in postmenopausal women. Understanding the mechanism of Letrozole involves delving into its role as an aromatase inhibitor and how it affects estrogen synthesis in the body.

Estrogen is a hormone that plays a vital role in the development and function of reproductive tissues, but it can also promote the growth of certain types of breast cancer. In postmenopausal women, most estrogen is produced not by the ovaries, but by the conversion of androgens (male hormones) into estrogen via an enzyme called aromatase. Letrozole works by inhibiting aromatase, thereby reducing the overall production of estrogen in the body.

The inhibition of aromatase by Letrozole occurs through a competitive binding process. Aromatase converts androgens such as testosterone and androstenedione into estrogen by facilitating the aromatization process, which involves the formation of an aromatic ring. Letrozole, a non-steroidal aromatase inhibitor, binds to the aromatase enzyme with high affinity, preventing it from converting androgens into estrogen.

By lowering estrogen levels, Letrozole decreases the stimulation of estrogen receptor-positive (ER+) breast cancer cells, which rely on estrogen to grow and proliferate. This reduction in estrogen can significantly slow down or even halt the progression of such cancers, making Letrozole an effective treatment for postmenopausal women with hormone-sensitive breast cancer.

In addition to its primary use in breast cancer treatment, Letrozole is sometimes prescribed off-label for other conditions. For instance, it can be used in the management of endometriosis and ovarian stimulation in fertility treatments. The mechanism remains consistent—by reducing estrogen levels, Letrozole can modulate conditions that are influenced by hormonal changes.

Adverse effects of Letrozole are generally related to the reduction in estrogen levels. Common side effects include hot flashes, joint pain, fatigue, and increased risk of osteoporosis due to lower bone mineral density. These side effects stem from the systemic decrease in estrogen, which plays various roles in maintaining bodily functions beyond just reproductive health.

In conclusion, Letrozole functions by inhibiting the aromatase enzyme, thereby reducing estrogen synthesis in postmenopausal women. This reduction in estrogen levels is crucial for treating hormone-sensitive breast cancers, as it limits the growth and proliferation of cancer cells that depend on estrogen. Understanding the precise mechanism of Letrozole helps in appreciating its therapeutic benefits and potential side effects, providing a comprehensive view of its role in medical treatments.