Neurofibromatosis Patients Have Increased Cancer Risk

​University of Turku press release

The hereditary neurofibromatosis type 1 (NF1) is one of the most common rare diseases. Worldwide, it affects about one in 3,000 people.

The disease usually manifests in early childhood as café-au-lait spots, which is light-brown pigmentation, as freckles in armpits and, after adolescence, as the growth of benign neurofibroma tumours on skin.

The new study shows that patients with NF1 are five times more likely to get cancer than the comparable population.  The study combined the unique registers and scientific expertise of the University of Turku and Finnish Cancer Registry.

The relative risk of cancer is highest on children and young adults, whose most common forms of cancer are brain and peripheral nerve tumours. Children with neurofibromatosis are 200 times more likely to get a brain tumour and over 2,000 times more likely to get peripheral nerve tumours than the comparable population.

– 38.8 percent of patients with neurofibromatosis get some type of a cancer by the time they are 50. In the comparable population, the figure is significantly lower, only 3.9 percent, says Professor Juha Peltonen from the University of Turku.

The study also confirmed that neurofibromatosis is also related to a higher risk of breast cancer. The risk is relatively greater on younger women: women under 40 are eleven times more likely to get breast cancer than the comparable population.
In addition to the increased cancer risk, neurofibromatosis patients with cancer have a poorer prognosis and a higher cancer mortality than the comparable population.

– Research results show that the NF1 gene is an important gene in the formation of cancer and its role in, for example, breast cancer should be studied further. The cancer risk of neurofibromatosis patients cannot be reduced but the reasons for a poor prognosis should be examined more closely. The prognosis can be better if the cancer is diagnosed early and therefore the neurofibromatosis patients and their doctors should be more aware of the cancer risk related to the disease, says Professor Peltonen.

As their research data, the group used the registers of the Finnish Cancer Registry on neurofibromatosis patients' incidents of cancer during a 25-year period from 1987 to 2012.

The same research group has previously demonstrated that one in 2,000 newborns in Finland has neurofibromatosis. Therefore, there are at least 1,500 people suffering from the disease in Finland.

– Today, the disease is usually diagnosed during childhood, but some adults with the neurofibromatosis have still not been diagnosed.

Neurofibromatosis is caused by mutations in the neurofibromatosis gene, i.e. a genetic error. However, about half the patients suffer from the disease because of a new mutation, which means that their parents do not have neurofibromatosis.