Many teenage boys experience some degree of enlargement of the breasts around the time of puberty. When the condition is troublesome, anti-estrogen drugs seem to be a safe and effective means of reducing breast size, according to a new study.

Pubertal gynecomastia, as the condition is called, occurs in up to 65 percent of boys, and about 10 percent of cases of do not resolve on their own within three years, researchers at the University of Ottawa explain in the Journal of Pediatrics.

“Even for those persons in whom the condition is self-limiting, it can be a troubling and at times psychologically disabling condition,” write Dr. Sarah E. Lawrence and colleagues.

They conducted a chart review of boys treated at their clinic with either tamoxifen or raloxifene, two drugs that block estrogen receptors, or who were not given any drug treatment.

Included in the review were 15 patients treated with tamoxifen for an average of 5.2 months, 10 with raloxifene for an average of 4.9 months, and 13 with no specific therapy other than reassurance.

Before treatment, the diameter of the breast nodule in these three groups averaged 4.6 centimeters, 3.8 cm and 4.7 cm, respectively.

Tamoxifen treatment led to an average decrease of 2.1 cm (45 percent) in breast diameter, compared with 2.5 cm (66 percent) in the raloxifene group. A 50 percent or greater reduction in size occurred in 41 percent and 86 percent of individuals in each group, respectively.

There appeared to be no adverse events, and no significant changes in hormone levels or liver enzymes.

The authors contacted subjects three years after the study period. None of those who had been treated reported a relapse, but 40 percent “were not completely satisfied with the response to treatment and went on to have surgery.”

Among those treated only with reassurance, 50 percent reported spontaneous resolution.

Lawrence’s team concludes that anti-estrogen treatment can be effective for pubertal gynecomastia, “with a better response to raloxifene than tamoxifen.”

However, they say, a clinical trial “using standardized measurements of glandular tissue, such as breast ultrasonography, is needed to further evaluate the use of estrogen inhibitors as medical therapy for boys troubled by persistent pubertal gynecomastia.”

SOURCE: Journal of Pediatrics, July 2004.