Tamoxifen, a drug for breast cancer, could help short boys get taller, researchers report.

The small, preliminary study states that short boys with “limited growth potential” who took tamoxifen had an increase in their predicted adult height.

Although the adolescent boys’ skeletons indicated lower predicted adult height, other signs of puberty stayed on track, write Nerissa Kreher, MD, and colleagues.

Kreher works in the pediatric endocrinology section of Riley Hospital for Children at the Indiana University School of Medicine.

The study appears in Pediatrics.

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Not a Direct Test

Kreher’s team checked the records of seven short boys who had taken tamoxifen twice daily for six months to four years. The boys were nearly 15 years old, on average.

Almost all of the boys (six out of seven) were also taking growth hormones at the same time.

The boys’ predicted adult height rose nearly 4 inches during tamoxifen therapy -- from 5 feet 6 inches to almost 5 feet 10 inches -- the researchers report.

Remember, those heights are predictions. The boys’ actual adult height isn’t known.

Was tamoxifen responsible for the results? It’s hard to say, especially in the boys who were also taking growth hormones, the researchers note.

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Side Effects

No side effects were recorded in the boys’ medical charts, with one exception.

One of the boys reported having blurry vision when he started taking tamoxifen. After stopping and then resuming the drug, those problems went away, write Kreher and colleagues.

Tamoxifen’s long-term effects weren’t part of the study.

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Off-Label Use

Tamoxifen isn’t approved for treating short stature. The drug blocks the hormone estrogen and is used to treat and prevent breast cancer in women.

Estrogen has many roles. It’s a key part of the female reproductive system. It also fuels some breast cancers, which explains tamoxifen’s use in breast cancer.

Estrogen may play a role in the mix of hormones that affect growth and physical maturation, write Kreher and colleagues.

The study was small and it didn’t directly test tamoxifen’s height effects, the researchers note.

They stress that more studies are needed to see if tamoxifen truly helps short, pubertal boys with limited growth potential improve their adult height.

By Miranda Hitti, reviewed by Louise Chang, MD

SOURCES: Kreher, N. Pediatrics, December 2005; vol 116: pp 1513-1515. Reuters.