A group of researchers led by Dr. Richard Legro of the Obstetrics and Gynecology Dept. of the Penn State College of Medicine in Hershey PA, studied the efficacy of the aromatase inhibitor (AI) letrozole (Novartis Femara) in helping women with PCOS and infertility (a common complication of the hormonal disorder) to conceive. They compared the fertility rate of 375 women on the drug as compared to an equal number on the standard treatment, clomiphene.
Clomiphene (Clomid) stimulates ovulation, and is commonly used to provoke increased egg production among women seeking to use in vitro fertilization to combat infertility. AI s such as letrozolepromote ovulation by inhibiting aromatase, an enzyme which is key in converting both androgen and estrogen precursors to the final hormone. In PCOS, the production and release of both types of hormones is impaired and irregular, leading to a host of hormonal-related metabolic disturbances: obesity, acne, irregular (or absent) periods, insulin insensitivity (contributing to diabetes), and hirsutism (a condition of unwanted male-pattern hair growth) in addition to difficulty conceiving. It is estimated that 5-10 percent of women of childbearing age suffer from PCOS to some degree.
The study s results showed significant comparative benefits for the AI as compared to clomiphene. Nineteen percent of the group on clomiphene had a live birth, while 27.5 percent of those on letrozole did so. This was further supported by the overall ovulation rate: 62 percent vs. 48 percent for the clomid group. There were no significant differences between the groups in terms of pregnancy loss or side-effects. The study appeared in this week s New England Journal of Medicine.
Two of the study s co-authors had these relevant comments:
This study showed conclusively that for this group of patients, treatment with letrozole resulted in proportionately more live births than did treatment with clomiphene, said Louis V. De Paolo, chief of NICHD s Fertility and Infertility Branch. And, the lead author, Dr. Legro, said: We are extremely encouraged that letrozole could provide a new, oral, first line therapy for this common disorder. A letrozole-based treatment potentially could provide a less invasive, less expensive therapy, with a much lower risk of multiple pregnancy.