As advances in treating pediatric cancers allow more and more patients to live into adulthood, doctors are increasingly concerned about the long-term health effects of the very treatments that saved them as children. 
 
 Researchers found, in a large study of adult survivors of childhood cancer, that more than 95% suffered from a chronic health condition by the age of 45, including pulmonary, hearing, cardiac and other problems related either to their cancer or the cancer treatment. 
 
 Many serious health conditions went undiagnosed until the participants joined the study, the researchers found, raising questions about whether survivors are receiving proper follow-up care given their higher risks for certain health problems later in life. 
 
 "Doctors may not be thinking about a heart-valve disorder in someone in his 30s, but if you had radiation to your chest at 10, this is something to think about," said Melissa M. Hudson, principal investigator and one of the authors of the study, which was published in JAMA. 
 
 The findings are based on a large, long-term health assessment involving more than 1,700 adults who were diagnosed and treated for cancer at St. Jude Children's Research Hospital in Memphis between 1962 and 2001. Study participants, who were at least 10 years past diagnosis, agreed to come back to St. Jude to undergo a battery of tests and physical examinations. In addition to overall health, researchers looked at some specific risks patients faced depending on the kind of cancer they had or the types of chemotherapy and radiation used to treat them. 
 
 The authors reported that among survivors who had undergone treatments associated with pulmonary risks, 65% were then found to have pulmonary problems. Of those exposed to cardiotoxic therapies, 56.4% turned out to have cardiac abnormalities. Many of these conditions were diagnosed as a result of the evaluations done for the study. 
 
 Dr. Hudson, of St. Jude and the University of Tennessee College of Medicine, Memphis, said oncologists believe some cancer treatments accelerate the aging process of organs. Researchers found that survivors who had received radiation to the brain exhibited mild cognitive deficits typically seen in older populations. Radiation to the chest often led to heart-valve changes, including scarring and leaky valves. Participants ranged in age from 18 to 60 years old, but given that the average age was 33, the health problems were considered striking. 
 
 The general population also faces greater health risks as it ages, but the study authors noted that the percentage of relatively young survivors with one or more chronic health conditions was "extraordinarily high." 
 
 "The prevalence of chronic health conditions is even higher than most of us would have anticipated," said Louis S. Constine, vice chairman of radiation oncology at University of Rochester Medical Center, who wasn't involved in the study. 
 
 Nick Dustman, a 44-year-old from Jacksonville, Fla., was treated at St Jude for Hodgkin's lymphoma when he was 16 and underwent high-dose radiation. Mr. Dustman said he doesn't smoke, watches his weight and bikes 120 miles every week. In the St. Jude study, he said he learned that people who received high doses of radiation often have heart issues. At the end of the testing, doctors told him to see a cardiologist immediately. Soon after, he underwent bypass surgery. "I never dreamed I had cardiac issues," he said. "Now I tell people St. Jude saved my life twice." 
 
 The latest estimates put the number of childhood cancer survivors at about 395,000, and these numbers are expected to grow, according to Dr. Hudson. 
 
 But "there is a paucity of training and doctors to take care of people with these specialized needs," said Charles Sklar, director of the long-term follow-up program in the department of pediatrics at Memorial Sloan-Kettering Cancer Center and one of the authors of the paper, which was funded by the National Cancer Institute and Alsac, the fundraising organization for St. Jude Children's Research Hospital. 
 
 Greater awareness of the issue has led oncologists today to try, whenever possible, to use lower doses of medicine and to avoid radiation. Oncologists say that long-term health risks should be lower in these cases. Nonetheless, the study authors noted that many of the same agents and treatments in the study are used today. 
 
 Write to Amy Dockser Marcus at amy.marcus@wsj.com 
 
 A version of this article appeared June 12, 2013, on page A3 in the U.S. edition of The Wall Street Journal, with the headline: Childhood Cancer Health Woes Persist.
– A giant bell on a billboard in St. Louis will ring every time a child completes chemotherapy at a local hospital, per the AP. The 12-foot-tall metal bell went up Wednesday on a billboard over Interstate 44 that reads "Childhood wins another round against cancer." Hospital staff will use a mobile app to trigger the bell every time a child completes cancer treatment at St. Louis Children's Hospital, explains the St. Louis Post-Dispatch. The bell's speakers enable people passing by to hear it ring. The hospital has its own bell that children with cancer can ring to mark their last day of chemotherapy, and five to 10 kids a month do so.