Neuroblastoma Causes

Neuroblastoma is a cancer that can develop in the nerve tissue of the neck, chest, abdomen or pelvis but the most common site of the primary tumor is the adrenal glands. Neuroblastoma that does not begin in the adrenal glands is most frequently found in the abdomen and chest. This is the second most common form of cancer in children. While it can occur in older children and adults, only 10 percent of the cases are found in people over the age of five. The exact cause of this rare cancer is unknown.

Biological Roots

• All cancers begin with a mutation that allows normal cells to grow and multiply out of control. The accumulating cells develop into a mass and eventually cells break away from this primary tumor site and invade other parts of the body. Neuroblastoma originates in the immature nerve cells in the fetus called neuroblasts. In normal development, neuroblasts mature to become the nerve cells of the adrenal glands. These cells should reach maturity by the time the baby is born but it is possible for some immature neuroblasts to remain after birth. If they do not quickly mature, they form a tumor (mass), which is called a neuroblastoma.

Genetics

• Researchers believe that the majority of neuroblastomas are not caused by genetic factors, in fact only 1 percent of the cases have a genetic component. However, a study completed in June 2009 by Dr. John Maris (University of Pennsylvania School of Medicine) and Dr. John Yu (Cedars-Sinai Medical Center) found a genetic trait---a "copy number variation"---in which DNA is not replicated properly. When present, this doubles the chances that a child will develop neuroblastoma.
  A study at the University of California in 1997 showed that over-expression of a gene called MYCN caused neuroblastoma in mice. Since high levels of MYCN are found in the adrenal gland in one-third of the cases, researchers continue to study its role as a causative factor. In 2008 a team from the Children's Cancer Research Institute in Austria found that increased levels of MYCN in those diagnosed with the disease indicated a poorer prognosis.

Parental Factors

• Since neuroblastoma occurs at such an early age, parental factors related to conception and gestation may be a factor. Theories related to occupation hypothesized that working around certain chemicals increased the child's chance of cancer. Smoking, alcohol consumption, medications during pregnancy and even exposure to infection during pregnancy have been considered but no current research has verified any of these possibilities.

Environmental Factors

• Studies conducted many years ago (1978) indicated that exposure to the pesticide chlordane increased the chance of neuroblastoma. Since the use of chlordane was stopped in 1988, this study may not be relevant today, however it served to direct attention to potential environmental causes. A study published in the journal Epidemiology in January 2001 studied 390 children with neuroblastoma. When compared to 460 non-cancerous control subjects, the team of researchers concluded that the use of pesticides around the home increased the chance of neuroblastoma by 60 percent.

Outcomes

• While researchers still don't know what causes neuroblastoma, they do know that the facts are grim. While 90 percent of the children diagnosed before the age of one have an excellent outcome, most children are diagnosed after the age of two. By then the cancer has already progressed to an aggressive stage. Treatment at such a high-risk stage consists of chemotherapy, radiation and stem-cell transplants. Unfortunately, it is fatal in about two-thirds of the cases. Researchers at many universities and research institutes continue to explore the causes as well as new and improved treatments.