As a dermatologist with extensive experience in skin cancer, I can explain the factors that can contribute to moles becoming cancerous. Moles themselves are not inherently harmful, but certain changes can indicate a risk of developing into a type of skin cancer known as melanoma.

Melanoma is the most serious form of skin cancer and is typically caused by damage to the DNA of skin cells, often due to exposure to ultraviolet (UV) radiation from the sun or tanning beds. Here are some factors that can increase the risk of a mole becoming cancerous:


1. Excessive Sun Exposure: Prolonged exposure to the sun without proper protection can lead to DNA damage in the skin cells that make up moles.

2. Fair Skin: People with fair skin that burns easily are at a higher risk because their skin has less melanin, which provides some protection against UV damage.

3. Family History: A personal or family history of skin cancer can increase the risk, suggesting a genetic predisposition.

4. Atypical Moles: Moles that are irregular in shape, have uneven color, or are larger than typical moles (the size of a pencil eraser or larger) are more likely to become cancerous.

5. Immunosuppression: Individuals with weakened immune systems, such as organ transplant recipients or those with HIV, are at a higher risk for skin cancers.

6. Changes in Moles: Any changes in the size, shape, color, or feel of a mole, or the development of new symptoms such as bleeding, itching, or crusting, should be evaluated by a healthcare professional.

It's important to note that not all changes in moles are signs of cancer, but they should be monitored and any concerning changes should be reported to a dermatologist.

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Researchers have found some gene changes inside mole cells that may cause them to become melanoma cells. But it's still not known exactly why some moles become cancerous while most don't. ... Genes that keep cell growth in check or cause cells to die at the right time are called tumor suppressor genes.read more >>