FRIDAY, Dec. 10, 2004 (HealthDayNews) -- While childhood cancers remain rare, the number of cases has been slowly but steadily increasing in Europe over the past 30 years, a new report claims.
An international team of researchers collected data on 113,000 cancers in children up to age 14 and more than 18,000 cancers in children between 15 and 19 years old. The data came from 63 cancer registries from 19 countries in Europe.
From the 1970s through the 1990s, the rate of cancer for children increased by about 1 percent per year; for the older teenagers, the rate increased by about 1.5 percent annually. By the 1990s, there were about 140 cases of cancer for every 1 million children and about 157 cases per 1 million teenagers, according to the report in the Dec. 11 issue of The Lancet.
Although the incidence of cancer rose, so did survival rates. "Children diagnosed with cancer during the 1990s had five-year survival of 75 percent in the west and 64 percent in the east of Europe," said lead researcher Eva Steliarova-Foucher, scientist in charge at the International Agency for Research on Cancer in Lyon, France. "As in other developed countries, survival has improved dramatically since the 1970s, when five-year survival was 44 percent for children and 50 percent for adolescents," she added. (For the purposes of the study, adolescents were those between 15 and 19 years old.)
Why cancer rates have risen is not clear. Steliarova-Foucher believes there are probably a number of different factors at work, including better methods of diagnosis and better reporting.
"Although we cannot entirely exclude improvements in diagnosis and registration, this natural development accounts for only part of the increase," she said. One popular theory holds that because children are being vaccinated against many childhood diseases, it leaves the body vulnerable to other diseases, including cancers.
"We believe that the underlying mix of factors responsible for the increase in incidence includes changes in childbearing and infectious pressure, linked especially to the rise of leukemias and lymphomas, two of the major tumor types," Steliarova-Foucher said.
In addition, the increased rate of cancers in Eastern Europe, which are higher than those seen in Western Europe, appears to be largely the result of the radiation released from the 1986 nuclear reactor accident at Chernobyl in the Ukraine, the researchers conclude.
Moreover, cancer survival in Eastern Europe is lower than in the west. "While population-based survival in Western Europe is comparable with that in the U.S.A., the children diagnosed in Eastern European countries fare markedly worse," Steliarova-Foucher said.
She believes that much work is needed to improve the diagnosis and treatment of children and adolescents with cancer. "The challenge for the newly enlarged European Union is obvious," she said.
"To improve survival of children diagnosed in the countries with low survival, the study of the status of the timeliness of diagnosis, referral mechanisms, and inclusion into clinical trials of children with cancer would be a basis for further decisions of how investment into the health-care system should be distributed," Steliarova-Foucher said.
Increases in childhood cancer rates have also been seen in the United States. "There was an increase in the incidence of all childhood cancers in the U.S. from about 1975 to 1985," said Dr. Michael Thun, vice president of epidemiology and surveillance research at the American Cancer Society. "After that, the trend flattened off, with only a marginal increase since then."
Thun believes the increase in cancers seen during that decade was largely due to improved methods of diagnosis. "Whether or not there are further increases in childhood cancers is open to question," he said.
As in Europe, cancer survival rates have increased. "The survival rate for all cancers combined has an absolute increase of 20 percent in boys and 15 percent in girls from [the] 1970s compared with the 1990s," Thun said. "The improvement in childhood survival is one of the success stories in cancer control. Childhood cancer used to be a death sentence, and now a substantial number of kids are cured or have sustained remissions."
However, Thun cautions that much needs to be done. "The challenge isn't over yet," he said. "There haven't been corresponding gains in how to prevent childhood cancers."
The American Cancer Society can explain childhood cancers.