WASHINGTON Boys treated with high doses of certain cancer drugs may suffer from fertility problems as adults, according to a study released on Thursday.

The study, published in the latest issue of the journal ****Cancer***, looked at a small group of men who were treated as children with drugs known as alkylating agents for a variety of sarcomas -- cancer of the bone, cartilage or certain muscles.

"The results indicate that exposure to alkylating agents prior to puberty is not protective and that the risk of infertility increases with higher doses of the therapy," said Lisa Diller, one of the study's authors and a pediatric oncologist at Dana-Farber Hospital and children's institute in Boston.

"It's important that parents of young patients be informed about the potential for long-term side effects," she added.

The researchers found that close to 60 percent, or 10, of the 17 men in the study had no sperm production. The study participants were between 16 and 34 years old.

Twenty-nine percent, or five of the men, had reduced sperm production, and only 12 percent, or two of them, had normal sperm counts. The two men with normal sperm counts were given the lowest doses of the chemotherapy drug, the study found.

Those chemotherapy drugs were known to produce fertility declines in adult cancer patients, said the study's lead author and pediatric oncologist, Lisa Kenney, but their long-term effect on children had not been studied until now.

The study looked at one alkylating drug called Cyclophosphamide, which Kenney said was used to treat a range of cancers in children as well as for certain immune diseases.

Those alkylating agents work by destroying fast-dividing cells in the body, which include cancer cells as well as cells in the testicles that produce sperm and hair cells and cells in the digestive tract.

All the patients treated prior to puberty had abnormalities in their semen, a finding that contradicted doctors' long-held belief that exposure to those drugs prior to puberty was safe for the male reproductive organs, the study said.

Kenney said in a telephone interview their research showed how important it was for child cancer survivors to be monitored into adulthood, adding that if children were past puberty when treated, then doctors should consider the option of storing the patient's sperm for possible use later.

"We must design therapies with late effects in mind -- reducing the dose intensity if possible in good-prognosis cancer cases. Of course, the most important thing is curing the patient, and late effects should never take priority over that," said Kenney.

(Reuter)