How common is cancer in children? Is cancer in childhood increasing?

Each year in the United States of America, about 10,000 children are diagnosed with some type of cancer. After accidents, cancer is the major cause of death in children between one and 16 years of age. Most of these cancer-related deaths will be due to brain cancer, which is the second most common type of cancer in children, after leukemia. One out of every 800 American adults is a survivor of childhood cancer.

Some studies have suggested that some types of childhood cancer have increased in incidence over the past 25 years. It is not entirely clear whether this increase is real, or due to earlier diagnosis of certain types of cancer that might not otherwise have been diagnosed until adulthood. The best example of this is some very slowly growing brain tumors that are now diagnosed earlier through special scans (Magnetic Resonance Imaging, or MRI, scans).

What causes cancer in children?

We know a lot about what doesn’t cause cancer in children. It has been estimated that fewer than 1% of all childhood cancers have any inherited or familial cause. Nationally performed , meticulously conducted clinical epidemiology studies of a wide variety of childhood cancers have generally failed to demonstrate any clear cut environmental links with the development of childhood cancer.

We believe that many childhood cancers, so-called embryonal cancers, reflect aberrations in development of tissues in the fetus (eg. Wilm’s Tumor or nephroblastoma; neuroblastoma; germ cell tumors; hepatoblastoma). These tumors appear to arise from primitive cells that failed to develop normally into mature, developed cells. What causes these residual primitive cells to then develop in childhood into cancers is not known, but the possibility of a second trigger- some environment factor, not otherwise damaging to most other children-which stimulates cancer growth, is under heavy study.

Can cancer in children be cured?

The treatment of childhood cancer has improved to such an extent that over 75-80% of children diagnosed with cancer in the year 2001 in North America will be eventually cured of their cancers. Clearly, the likelhood of cure in any one child depends upon several factors, including the type of cancer, the extent of disease at diagnosis (localized in one place or spread to other parts of the body) and for solid cancers, whether the localized tumor can be surgically resected. Our current challenge is: (1) to identify more accurately those 20-25% of children who are destined not to be cured at present with our currently-available treatments, and (2) to improve the cure rate of such children with new treatment strategies.

Is the treatment for childhood cancer permanently damaging?

In North America, about one in every 800 adults is a survivor of childhood cancer. Pediatric cancer specialists have been paying special attention to the quality of life of survivors of childhood cancer for as long as we begun to recognize that such children could indeed be cured of their cancers. As the cure rates have improved, we have also been able to reduce the intensity of treatment for many cancers of childhood, sustaining the same high cure rates, but with much less long term toxicity. Thus, the diminishing use of radiation therapy and certain drugs toxic to the heart and lungs, has resulted in children treated in the last 15 years with fewer permanent side-efects on physical and intellectual growth, or left with heart, lung or kidney disease.

The "truly cured child", a concept coined in the 1970s, is a child not only cured of his cancer, but also able to fulfil all the expectations in adult life of educational, professional and social achievements – a job, a family and a fully active place in his or her community. This is now a reality for the majority of survivors of childhood cancer.

How long is the treatment for children with cancer?

In the early 1960s, when we first began to realize that some children with acute leukemia could be long term survivors, it was considered that treatment for childhood leukemia needed to be life long. Now, through carefully controlled studies, we now know that treatment of acute lymphoblastic leukemia (the single most common childhood cancer) ranges from 2 to 3 years. For many solid tumors, including lymphomas and Wilms’ tumor, the duration of treatment has been steadily reduced, so that treatment for such cancers may now include less than six months of chemotherapy. For other solid tumors, treatments generally vary from six to 12 months’ duration.

What’s new in the treatment of young children with malignant brain cancer?

One of the biggest remaining challenges is how to both increase the survival rate and improve the quality of life of survivors, amongst the youngest children diagnosed with malignant brain tumors. Not only have such children’s tumors proven very difficult to cure, but the use of radiation therapy to the brain has long been recognized to have devastating effects upon intellectual function of these young children. One of the major efforts of our Program has been the ‘Head Start’ treatment protocols, developed by Dr. Jonathan Finlay about ten years ago, and further refined in the last 3-4 years here at NYU. In these protocols, brief (less than six months) but very intensive chemotherapy is used to try to avoid radiotherapy to the brain, or at least permit a significant reduction in the dose of brain irradiation, for all children under 10 years of age diagnosed with malignant brain tumors. These studies have been conducted with the participation of major pediatric cancer centers throughout North America, South America and Australia. Results of these studies support the application of these treatment plans in such young children for several types of malignant brain tumors of young children.

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