Neuroblastoma - This Battle Which I Must Fight: Cancer in Canada's Children and Teenagers

NEUROBLASTOMA

Ninety-five percent of tumours of the sympathetic nervous system are neuroblastomas. Each year in Canada, approximately 65 young people are diagnosed with this cancer, which occurs with equal frequency in boys and girls (Table 1). Neuroblastoma accounts for five percent of cancers in children and teenagers, but one quarter of cancers among infants younger than one year of age. Almost 90 percent of neuroblastomas are diagnosed in children younger than five years of age.

Neuroblastoma arises in embryonic neuronal cells in the neck, chest, abdomen or pelvis. It is often present at the time of birth, but usually does not produce symptoms until later. Occasionally, neuroblastoma is diagnosed before birth by ultrasound.

Children with neuroblastoma may be unwell because of problems related to the tumour at its original site or because of problems related to the spread of the tumour. Neuroblastomas produce chemicals called vanillylmandelic and homovanillic acid which are excreted in the urine and permit early detection of the tumour.(139) Some neuroblastomas in infants disappear spontaneously, even those that are widespread. Occasionally this tumour matures into a benign lesion.

The tumour is removed surgically and the diagnosis is confirmed by microscopic examination of its cells. Other special tests detect high-risk features of the tumour, such as the genetic make-up of the cancer cells, that indicate the need for more aggressive treatment. Neuroblastoma may spread to other sites in the body, especially to the lymph nodes, bone marrow, liver, bones, tissues around the eye socket and skin. More than 70 percent of children with neuroblastoma who are over the age of one year at the time of diagnosis have advanced disease with distant spread.

Children younger than one year of age and without widespread disease have the best prognosis.(29) Surgery alone has produced long-term disease-free survival rates of more than 90 percent in children with localized neuroblastoma. A combination of surgery, chemotherapy and radiation therapy is used to treat children with advanced disease. Optimal therapy is still lacking for most children older than one year of age diagnosed with metastatic neuroblastoma; however, treatments for these children are evolving and the role of bone marrow transplantation is being explored. The five-year survival rate for Canadian children and teenagers diagnosed with all types of sympathetic nervous system tumour between 1985 and 1988 was 60 percent (Table 7).

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