The first generation to survive childhood cancers in large numbers is discovering that some of the same treatments that destroy tumors with toxic force can cause serious side effects to surface years later.
As more children outlive their cancers, doctors are drawing links between curative therapies and delayed problems such as early puberty, sterility, stunted growth, learning disabilities and weakened hearts.
At the Johns Hopkins Oncology Center, physicians are taking a second look at cured patients to see if they are suffering long-term effects of treatment.
They have found people like Chris Staub, 8, a second-grader from Pennsylvania who has already entered puberty because radiation prematurely flipped a hormonal switch in his brain. When he was just a year old, X-rays destroyed a malignant brain tumor.
Then, there's Eric Kincaid, 26, of East Baltimore, who survived leukemia at 10 but quit school in the 10th grade because he couldn't concentrate and complete his work -- the possible result of radiation treatments that targeted his brain.
Delayed side effects are a cruel blow for many people who ended years of surgery, chemotherapy and radiation believing the ordeal of cancer was over.
Learning the cause, however, can be strangely liberating.
"In a weird kind of way, it was gratifying, like turning on a light," Mr. Kincaid said. "At least I know it's not totally me."
As many as 10 percent to 15 percent of children who survive cancer suffer severe complications in the years that follow -- while up to a quarter suffer mild to moderate symptoms, some studies show.
Radiation treatments that burn away brain tumors also can hinder learning, retard growth and spawn new cancers. One class of anti-cancer drugs can weaken the heart, placing patients at risk for heart failure as they age.
Some drugs damage sex organs, forcing youngsters to face the prospect that they will never conceive when they grow up.
This year, doctors and nurses at the Johns Hopkins Oncology Center have begun to track patients who were declared cured five, 10, even 20 years ago. Their goal is to document and help people overcome the delayed consequences of treatments -- and to fashion therapies that are less damaging but no less effective.
Hopkins has contacted 100 of the 700 people who have survived at least five years past therapy. Doctors and nurses are evaluating five new patients a week, and hope to see 200 survivors by year's end.
Many people are hearing for the first time that treatments that saved their lives might explain why they can't keep up in class or hold down a job.
"Some of the problems are subtle," said Dr. Cindy Schwartz, who heads the "late effects" clinic at the Johns Hopkins Oncology Center.
"Some of these children are not retarded, but school is a little more difficult for them. They were passed along in the school system. They were quiet and didn't get great grades, and they ended up not learning a lot."
Long-term effects weren't much of a problem in years past, when cancer simply killed the vast majority of its young victims. In the 1960s, for instance, doctors cured only about 10 percent of afflicted children.
The ballyhooed War on Cancer has failed on many fronts -- such as curbing breast cancer deaths -- but it has scored shining victories against childhood leukemia and some solid-tumor cancers. Today, doctors estimate that two-thirds of afflicted youngsters will survive their malignancies.
Dr. Curt I. Civin, chairman of pediatric oncology at Hopkins, said he cannot credit revolutionary treatments. There have been few, but doctors have become more creative in deploying old drugs along with radiation and surgery.
Doctors, for instance, have learned to use chemotherapy drugs in combinations rather than singly.
This way, if a tumor becomes resistant to one drug, it might succumb to another before it gathers strength and grows.
"But these battles are being won with drugs that aren't very smart," Dr. Civin said.
Drugs that poison tumors are equally capable of damaging organs, glands and brain cells, he said.
James and Kimberly Staub of New Oxford, Pa., didn't worry much about long-term effects when their son Chris, at the age of 1, was diagnosed with a brain tumor.
They wanted him cured.
The diagnosis explained why their little boy leaned into people's faces in order to see them, why he crashed into doors and why his eyes jumped from side to side.
L The tumor, resting against the optic nerve, had to come out.
The Staubs weren't surprised that surgery, radiation and chemotherapy left him legally blind. The tumor's location virtually ensured that.
He has coped well. In school, he learns quickly and gets good grades. He is helped by a classroom aide who stays by his side throughout the school day and an optical device that greatly enlarges print on a screen.