Why your skin cells sometimes forget how to stop growing

Science · Published 25 October 2026 Swipe more like this →

In short: Melanoma is more than just a surface growth; it is a fundamental failure of cellular communication. When specific enzymes become stuck in the 'on' position, they send constant signals for cells to multiply, turning protective pigment-producing cells into an aggressive, spreading malignancy.

Melanoma originates in melanocytes, the specialized skin cells responsible for producing melanin—the pigment that protects our bodies from ultraviolet (UV) radiation. While many skin conditions are benign, melanoma is uniquely dangerous because it is always malignant and possesses a high propensity to spread throughout the body. It currently accounts for nearly three-quarters of all skin cancer deaths worldwide, with over 325,000 new cases diagnosed annually as of 2020.

The pathology centers on a breakdown in DNA integrity. While UV radiation from sunlight is the most common driver of these mutations, some instances are inherited or occur spontaneously. A critical mechanism involves the BRAF gene, which produces B-raf—a kinase enzyme that normally acts as a messenger. In about 50 percent of melanoma cases, spontaneous mutations create a version of this protein that is constantly active. Instead of waiting for instructions from cell surface receptors, the mutant B-raf continuously signals the nucleus to stimulate cell differentiation and suppress apoptosis (programmed cell death).

This unregulated signaling creates a feedback loop of uncontrolled proliferation. Because these cells no longer respond to the body's natural 'stop' signals, they form tumors that can be difficult to treat. Understanding this specific genetic pathway has allowed researchers to explore targeted therapies, such as focusing on the B-Raf oncogene to disrupt the cancer's growth signals at the molecular level.

Risk factors vary significantly across populations. For example, white people are estimated to be 20 times more likely to develop melanoma than Black people. Other high-risk indicators include fair skin, a tendency to freckle easily, and having a large number of moles—or several very large ones.

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