When an adult develops cancer, it is often related to lifestyle or external factors. In children, the disease often develops very quickly. No one knows why children and teens develop cancer. However, there is a great deal of knowledge about what makes a normal cell turn into a cancer cell.

Cell changes and cancer

Normal body cells can have many different functions. Some are meant to produce hormones, some develop into nerve cells, others are to become liver cells and so on. How often these cells are supposed to divide is controlled by our DNA, which each cell has in its nucleus.

DNA molecules are the blueprint for our bodies, and this blueprint is spelled out in chromosomes. The molecule looks like a ladder, and its rungs are much like a barcode. If there’s a mistake in a barcode, then it provides incorrect information.

The same is true if there’s an error in one of the ‘rungs’ on the DNA molecule. If the flaw is in the wrong place, it can lead to uncontrolled cell division, and this leads to tumours.

When the DNA is changed in a way that turns a normal cell into a cancer cell, this does not make the cancer hereditary.The change occurs only in that cell, not in the rest of the body.

Different types of cancer occur at different ages

Some cancer types affect small children, while others affect older children and teenagers.

Typical cancers among small children are renal tumours (Wilms tumour) and neuroblastoma, a tumour in the neural tissue near the spinal cord.

Another typical cancer for small children is leukaemia. These cancer types are almost unheard of after eight years of age.

Bone tumours rarely strike before the age of eight or nine and are viewed as typical teenage cancers.

Brain tumours occur in all age groups.

Treatment and outlook

In Sweden, nearly one child a day is diagnosed with cancer, and about 1,000 children and teens are under treatment. Around 80% survive, thanks to major progress in the past 40 years in research, treatment and nursing.

Treating a child with cancer is a special situation for the health care system.The sick child is not the only victim – the entire family’s life changes. In addition to medical care, the young patient, his or her siblings and parents also need support. For example, children with cancer need support for their schooling, and their families need accommodation at the hospital.

How cancer occurs

Cancer can occur when there is a problem in one of the body’s cells.

Usually cells can repair the damage; if one cannot, it triggers a mechanism that causes the cell to die.

In a cancerous cell, that mechanism does not work. Instead the changed cell grows and divides uncontrollably, eventually developing into a clump of cancer cells called a tumour.

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Reviewed by: Klas Blomgren, överläkare och professor vid Karolinska Institutet, januari 2017