The treatment of childhood cancer is a major success story. Twenty-five years ago, only 10% of children with leukemia
The treatment of childhood cancer is a major success story. Twenty-five years ago, only 10% of children with leukemia survived, now this has increased to 70%, said Professor Tom Voûte of the Department of Pediatric Oncology, Emma Kinderziekenhuis, Amsterdam, The Netherlands. He spoke at ECCO 9, the 1997 European Cancer Conference.
In Europe, only 1 child under the age of 15 develops cancer for every 100 adults who develop cancer.
However, there are still serious problems to be resolved, added Professor Voûte. Successful therapy often has its own risks. The results of treatment are too often marred by the inability of radiotherapy and anticancer drugs to distinguish between normal and diseased tissue.
Children cured of cancers are at an increased risk of developing second cancers later in life and need a prolonged follow-up. This applies especially to patients with genetic alterations and patients treated with radiotherapy, alkylating agents, and epipodophyllotoxins.
However, there is hope for the future. Strategies are being developed worldwide that will minimize the late adverse effects of treatment while further improving cure rates. Unnecessary treatments have been discarded, new drugs are being introduced, and radiotherapy is more targeted than in the past.
One particularly distressing problem for children who survive cancer into adult life is that their treatment may have made them infertile. Exciting advances in the field of fertility preservation are taking place, however.
The cryopreservation of testicular or ovarian tissue removed before treatment and subsequent grafting of this tissue after complete remission are now possible in some cases, and in vitro maturation of individual cryopreserved gametes and subsequent fertilization by intracytoplasmic sperm insertion (ICSI) is a possible alternative in others.
Parents should make their life styles as healthy as possible for the sake of their children, says Professor Voûte. We know that maternal smoking in pregnancy and marijuana use increase the risk of childhood leukemia and that the children of mothers using hair dye are at high risk of Wilms tumor. Heavy alcohol consumption by the mother also increases cancer risks. All these risks are avoidable.
Advances are also occurring in researchers ability to identify children who are at high risk of cancer from genetic abnormalities. It has been shown that children who develop second cancers in childhood may have a genetic abnormality of the p53 gene, but there are probably many more, so far unidentified, genetic associations with childhood cancer.
Since 60% of children with cancer are cured, 1 in 1,000 of the population will be survivors of childhood cancer. These individuals will need careful monitoring, as the risk of developing a second cancer is increased with increased exposure to radiation, says Professor Voûte. This has important implications for the planning of future therapy. We must develop protocols that achieve the best balance between long-term risks and benefits.