Letrozole is a medication primarily recognized for its role in breast cancer treatment, particularly for postmenopausal women with hormone receptor-positive cancers. It also serves an important purpose in fertility treatments, where it helps stimulate ovulation. A common question arises regarding Letrozole’s connection to ovarian cysts, prompting a closer look at how this medication interacts with ovarian function.
Understanding Letrozole’s Action
Letrozole functions as an aromatase inhibitor. This means it blocks the enzyme aromatase, which converts androgens into estrogens in the body’s tissues, including the ovaries. By inhibiting aromatase, Letrozole significantly reduces estrogen production. The body’s natural feedback system then interprets this lower estrogen level as a signal to produce more Follicle-Stimulating Hormone (FSH). This increase in FSH directly stimulates the ovaries to develop and mature follicles, which are the sacs containing eggs.
Ovarian Cysts Explained
Ovarian cysts are fluid-filled sacs that can develop on or within an ovary. The most common types are functional cysts, which are a normal part of the menstrual cycle. These include follicular cysts, which form when a follicle grows but fails to release an egg, and corpus luteum cysts, which can develop if the follicle that released an egg fills with fluid or blood after ovulation. Functional cysts are benign and frequently resolve on their own within a few menstrual cycles.
Letrozole’s Role in Cyst Formation
Letrozole’s mechanism of stimulating ovarian activity can lead to the formation of functional ovarian cysts. By increasing FSH levels, the medication encourages the ovaries to develop multiple follicles or to grow existing follicles larger than usual. If these stimulated follicles do not rupture and release an egg, they can persist and become follicular cysts. Similarly, a corpus luteum cyst might form if the follicle ovulates but then fills with fluid and persists. These cysts are a temporary and expected consequence of the drug’s intended action to induce ovulation, rather than a harmful side effect.
When Cysts Occur During Letrozole Treatment
Functional cysts that develop during Letrozole treatment often do not cause symptoms, but large ones can cause pelvic pain, pressure, or bloating. Monitoring during Letrozole treatment involves ultrasound scans to identify developing cysts. A baseline ultrasound before starting treatment can help rule out existing cysts. Seek medical attention if severe or sudden pelvic pain occurs, especially with nausea or vomiting, as this could indicate a cyst rupture or ovarian torsion. Most Letrozole-induced cysts are benign and tend to resolve spontaneously, often by the next menstrual cycle.