More than two-thirds of British teenagers with cancer are not being warned that treatments they receive could cause infertility, a cancer charity said on Monday.

Sixty-six percent of 450 teenagers with cancer who were questioned at a recent conference said they had not been counseled about fertility issues before they were treated for the disease.

Half the adolescents who had been told about the side effects of the treatment were not satisfied with the information they had been given. Others were told when it was too late to do anything about it.

“One might think fertility is not an issue for a 13 or 14-year-old teenager with cancer. Views expressed this weekend demonstrated that the opposite is true. Teenagers must be given a choice,” Simon Davies, head of the Teenage Cancer Trust, said in a statement.

Cancer is the most common cause of natural death in teenagers. About 1,500 new cases are diagnosed each year in Britain. Although young people develop specific types of cancer and have different medical and psychological needs, they are usually treated with children or adults.

Three-quarters of the teenagers questioned for the survey said they were in wards with young children or adults but most would have preferred to be in wards with other adolescents.

Ninety percent of the teenagers questioned in the poll said they would be willing to travel up to two hours or more to receive treatment in a hospital that caters for teenagers and young adults with cancer.

Leukemia, lymphoma and brain tumors are the most common types of cancer affecting children and teenagers. Doctors suspect genetic susceptibility may be important because children and teenagers are too young to have chronic exposure to environmental factors.