W hat causes GEP-NETs?

No-one knows exactly what causes GEP-NETs to grow. Generally, a change in the DNA of a cell starts a process whereby the cell doesn’t behave as normal.

The cell then divides and creates a copy of itself which also has the faulty DNA. These cells carry on dividing and growing in number uncontrollably until there is a tumour or cluster of abnormal cells.1

The change in the DNA may be caused by genetics (i.e. you get it from a parent) or by things that happen over your lifetime, such as exposure to tobacco smoke, radiation and certain chemicals in the environment.1

About 1 in 10 cases of GEP-NETs is related to a genetic condition.2 If you have been diagnosed with one of these conditions and you start to notice any new symptoms, talk to your doctor straight away:2

  • multiple endocrine neoplasia 1 (MEN1)
  • von Hippel Lindau (VHL)
  • Neurofibromatosis Type 1 (NF1) and
  • Tuberous Sclerosis (TS)


  1. CRUK. Genes, DNA and Cancer. Available at: Last accessed October 2020.
  2. O’Shea T, Druce M. When should genetic testing be performed in patients with neuroendocrine tumours? Rev Endocr Metab Disord. 2017; 18(4): 499–515.