Melanoma is a cancerous tumour that forms in the pigment-producing cells, known as melanocytes, which produce melanin that causes the skin to brown or tan.

The primary cause of melanoma is exposure to ultraviolet light from the sun or other sources, such as tanning beds. This exposure causes damage to the DNA, which controls the cell, leading to the development of cancer.

Melanomas may start in the skin, but if left alone they can spread to other parts of the body. There are five stages of melanoma: 0, I, II, III and IV. Stage III melanoma is defined as the point where the melanoma has spread to your lymph nodes (part of the body’s waste removal and immune system). Stage IV melanoma is known as metastatic melanoma and indicates that the melanoma has spread to other parts of the body. 

BRAF V600-positive melanoma

BRAF is a protein that acts as a ‘switch’ in normal cells. It is ‘switched on’ by specific signals when needed and activates other proteins that help regulate the way cells multiply and grow. The BRAF gene (which provides the code for creating the BRAF protein) can be changed, or ‘mutated’, in some cancers, including melanoma. When melanoma is BRAF V600 positive, the ‘switch’ is ‘on’ all the time, and ultimately contributes to uncontrolled cell growth.

V600 is the most common BRAF mutation found in people with melanoma. Approximately 50% of people with unresectable or metastatic melanoma have a BRAF mutation.1 



  1. Cheng L et al. Mod Pathol 2018;31:24–38.
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ONC20-C023a May 2020

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