The overall cure rate for the 20,000 children diagnosed with cancer in the United States each year is more than 75 percent. Sounds good -- especially when 50 years ago, most children diagnosed with cancer died. But considering that only one in three childhood cancer survivors remain healthy, perhaps this is not such good news.

Thirty years after diagnosis, about 40 percent of survivors have a serious health problem and one-third have multiple problems. Strokes, heart disease, and kidney failure are just a few of the major health concerns that plague many survivors who have entered adulthood.

Doctors have long known that cancer treatments can cause new cancers later in life. But the Childhood Cancer Survivor Study -- the largest ever childhood study of its kind -- shows there are other long-term health problems. Researchers studied 10,000 survivors -- past studies examined 200-300 survivors -- and found these survivors were eight times as likely as their siblings to develop severe and life-threatening conditions. They found survivors of bone tumors, nerve and brain cancer, and Hodgkin's disease faced the highest risk.

The source of these later-in-life health problems vary. Kidney failure may result from damage caused by chemotherapy or radiation or the infections children suffer when their immune systems are weakened. Drugs used to treat infections may also be to blame. Strokes may result from head and chest radiation.

Cancer treatment for people of all ages comes with a price. We buy time, we buy life in exchange for the unknown. But for children -- who stand to live longer than adults -- there is a greater unknown. Sadly, there is a dark side to surviving cancer.