Skin cancer is the most common form of cancer, affecting more than 3 million Americans annually. The cancer forms when skin cells mutate and grow abnormally, usually as a result of sun exposure. However, this form of cancer can also appear on parts of the body that are not typically exposed to sunlight.

While skin cancer is very common, it is not often deadly. Only certain, rare forms of skin cancer metastasize, or spread, quickly enough to be life-threatening. Still, early diagnosis and treatment are important. Treatment usually involves biopsy and surgery, while the more severe forms of cancer might require chemotherapy and/or radiation therapy.

Types of Skin Cancer

There are three common types of skin cancer, but they vary significantly in danger. Basal cell carcinoma, for example, comprises between 80 and 85% of all skin cancers, but it is not often lethal. It affects the lowest layer of the epidermis and looks like a small, red or flesh-colored mole. These are generally the least dangerous skin cancers, as they rarely metastasize or become life-threatening.

Squamous cell carcinoma, on the other hand, accounts for just 10% of all skin cancers, but it is often similarly benign. This form of skin cancer is usually found on parts of the body that are damaged by UV rays, like the head, neck, chest, arms, and upper back. This is a slow-growing skin cancer, and it is easily treated. However, squamous cell carcinoma has been known to metastasize, increasing its lethality.

The deadliest form of skin cancer is melanoma. While it makes up just 5% of all skin cancers, it is the most likely to metastasize. It often looks like a dark growth that changes in size and borders and can grow asymmetrically. Melanoma can spread quickly and easily, so early detection and treatment is essential.

There are other types of less common skin cancers, including:

  • Kaposi sarcoma
  • Merkel cell carcinoma
  • Sebaceous gland carcinoma

With all forms of skin cancer, detection and early treatment result in the best possible prognosis. However, it can be difficult to know which moles and bumps change, which are new, and which may be malignant. Making regular appointments with a medical dermatologist for skin exams is an easy way to track growths and screen for skin cancer.


According to the Mayo Clinic, symptoms of skin cancer may include:

  • A pearly or waxy bump
  • Flat, flesh-colored scar-like lesion(s)
  • Bleeding or scabbing sores that heal and return
  • Firm, red nodules
  • Flat, scaly, and crusted lesions
  • Large brownish spot with dark speckles
  • Moles that change in color, size, feel, and borders
  • Painful lesion that burns or itches


Several factors are associated with the etiology of skin cancer. According to the National Council on Skin Cancer Prevention, the following experiences put individuals at a greater risk of developing this form of cancer.

  • Fair skin
  • Old age
  • Having experienced radiation treatment
  • Having had a prior skin caner
  • Excessive UV light exposure
  • Genetics
  • Being over 40 years old
  • Weakened immune system
  • HPV
  • Smoking
  • Basal cell nevus syndrome

Skin Cancer Glossary

  • Benign: Not cancerous
  • Biopsy: The removal and examination of a small piece of tissue that determines whether cancer cells are present
  • Cryotherapy: A treatment that involves a medical professional spraying liquid nitrogen on pre- or early cancers
  • Brachytherapy: A form of radiation used to treat nonmelanoma skin cancer
  • Electrodessication and curettage: A fast treatment for nonmelanoma skin cancers that involves scraping the lesion and burning the open wound
  • Lesion: A part of the skin that has an abnormal growth or appearance, like a birth mark, a moles, or acne
  • Nevus: A medial term for mole
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