Learn more about this course.

Germline or somatic testing

Distinguish between germ-line testing for familial cancers, and somatic testing for different tumour types.

So far we have discussed gene variants which are germ-line.

Germ-line variants are present in every cell in the body, including sperm and ova, meaning they have the potential to be inherited. Somatic variants arise in cells and tissues after conception, and therefore cannot be inherited. Somatic variants are they main mechanism in which cancer develops and evolves. The newer ‘targeted’ cancer therapies target somatic variants; Herceptin treatment for Her2 receptor positive breast cancers, and BRAF inhibitors for BRAF positive melanoma are examples in routine oncological practice.

It is important to distinguish between somatic and germ-line variants: patients may be informed that there is a ‘genetic mutation’ in their cancer, or it is ‘genetic’, and this can lead to misunderstanding that it is inherited.

The linked RCGP infographic summarises the differences.

How might you advise a patient who was confused about the results of a cancer genetic tests and whether their cancer was inherited?