Sun Exposure and Skin Cancer

Medically Reviewed by Stephanie S. Gardner, MD on September 18, 2023
Written by WebMD Editorial Contributors
6 min read

The sun's rays make us feel good, and in the short term, make us look good. But our love affair isn't a two-way street. Exposure to sun causes most of the wrinkles and age spots on our faces. Consider this: One woman at age 40 who has protected their skin from the sun actually has the skin of a 30-year-old!

We often associate a glowing complexion with good health, but skin color obtained from being in the sun – or in a tanning booth – actually accelerates the effects of aging and increases your risk for developing skin cancer.

Sun exposure causes most of the skin changes that we think of as a normal part of aging. Over time, the sun's ultraviolet (UV) light damages the fibers in the skin called elastin. When these fibers break down, the skin begins to sag, stretch, and lose its ability to go back into place after stretching. The skin also bruises and tears more easily -- taking longer to heal. So while sun damage to the skin may not be apparent when you're young, it will definitely show later in life.

Exposure to the sun causes:

  • Pre-cancerous (actinic keratosis) and cancerous (basal cell carcinoma, squamous cell carcinoma and melanoma) skin lesions - due to decreases in the skin's immune function
  • Benign tumors
  • Fine and coarse wrinkles
  • Freckles
  • Discolored areas of the skin, called mottled pigmentation
  • Sallowness -- a yellow discoloration of the skin
  • Telangiectasias -- the dilation of small blood vessels under the skin
  • Elastosis -- the destruction of the elastic and collagen tissue (causing lines, wrinkles and sagging skin)

Skin cancer is the most prevalent form of all cancers in the U.S. and the number of cases continues to rise. It is the uncontrolled growth of abnormal skin cells. This rapid growth results in tumors, which are either benign (noncancerous) or malignant (cancerous).

There are three main types of skin cancer: basal cell carcinoma, squamous cell carcinoma and melanoma. Basal cell and squamous cell cancers are less serious types and make up 95% of all skin cancers. Also referred to as non-melanoma skin cancers, they are highly curable when treated early. Melanoma, made up of abnormal skin pigment cells called melanocytes, is the most serious form of skin cancer and causes 75% of all skin cancer deaths. Left untreated, it can spread to other organs and is difficult to control.

Ultraviolet (UV) radiation from the sun is the number-one cause of skin cancer, but UV light from tanning beds is just as harmful. Exposure to sunlight during the winter months puts you at the same risk as exposure during the summertime, because UVA rays are present in daylight.

Cumulative sun exposure causes mainly basal cell and squamous cell skin cancer, while episodes of severe sunburns, usually before age 18, can raise the risk of developing melanoma. Other less common causes are repeated X-ray exposure and occupational exposure to certain chemicals.

Although anyone can get skin cancer, the risk is greatest for people who have fair or freckled skin that burns easily, light eyes, and blond or red hair. Darker-skinned individuals are also susceptible to all types of skin cancer, although their risk is substantially lower.

Aside from complexion, other risk factors include having a family history or personal history of skin cancer, having an outdoor job, and living in a sunny climate. A history of severe sunburns and an abundance (greater than 30) of large and irregularly shaped moles are risk factors unique to melanoma.

The most common warning sign of skin cancer is a change on the skin, typically a new mole or skin lesion or a change in an existing mole.

  • Basal cell carcinoma may appear as a small, smooth, pearly or waxy bump on the face, ears or neck, or as a flat pink, red or brown lesion on the trunk or arms and legs.
  • Squamous cell carcinoma can appear as a firm, red nodule, or as a rough, scaly flat lesion that may bleed and become crusty. Both basal cell and squamous cell cancers mainly occur on areas of the skin frequently exposed to the sun, but can occur anywhere.
  • Melanoma usually appears as a pigmented patch or bump but can also be red or white. It may resemble a normal mole, but usually has a more irregular appearance.

When looking for melanoma, think of the ABCDE rule that tells you the signs to watch for:

  • Asymmetry -- the shape of one half doesn't match the other
  • Border -- edges are ragged or blurred
  • Color -- uneven shades of brown, black, tan, red, white or blue
  • Diameter -- A significant change in size (greater than 6mm), although any mole that is getting larger should be brought to the attention of your dermatologist; many melanomas are being diagnosed at much smaller diameters.
  • Evolving -- any new spot or mole that is changing in color, shape or size or itches or bleeds.

Skin cancer is usually diagnosed by performing a biopsy. You'll be awake for this short, in-office procedure. First, you'll get some local anesthesia, which means it will numb just that area of your skin.

A biopsy involves taking a sample of the tissue, which is then placed under a microscope and examined by a dermatopathologist, or doctor who specializes in examining skin tissue.

Treatment of skin cancer is individualized and is determined by the type of skin cancer, its size and location, and the patient's preference.

Standard treatments for non-melanoma skin cancer (basal cell or squamous cell carcinomas) include:

  • Primary Excision -- excision of the skin cancer under local anesthesia with a margin of normal tissue
  • Mohs surgery (for high-risk skin cancers or skin cancers in high-risk areas) – excision of cancer with immediate microscopic examination to ensure clear margins and to ensure complete removal of the cancer
  • Electrodesiccation and curettage -- physically scraping away the skin cancer cells, followed by electrosurgery (heat destruction of tissue)
  • Cryosurgery or freezing -- You'll get this done in your doctor's office. They will use a spray, cotton swab, or metal device called a cryoprobe to apply extremely cold liquid nitrogen to the cancer. This freezes the cancer cells and the immediate surrounding cells. The frozen skin thaws and forms a scab, which eventually falls off, leaving a white scar.
  • Topical chemotherapeutic creams -- Your doctor will prescribe a cream, solution, or gel for you to use at home on an area of your skin where you have precancerous growths or directly on a skin cancer. You'll use it nightly, twice daily, or three times a week for as long as 3 months. These treatments destroy the cancer cells.

Standard treatments for melanoma skin cancer include:

  • Wide surgical excision
  • Sentinel lymph node mapping (for deeper lesions) to determine if the melanoma has spread to local lymph nodes
  • Drugs (chemotherapy, biological response modifiers) for widespread metastatic disease
  • Radiation therapy for local control of advanced melanoma in areas such as the brain
  • New methods in clinical trials

Nothing can completely undo sun damage, although the skin can somewhat repair itself, especially with on-going sun protection. So, it's never too late to begin protecting yourself from the sun. Your skin does change with age -- for example, you sweat less and your skin can take longer to heal, but you can delay these changes by staying out of the sun. Follow these tips to help prevent skin cancer:

  • Apply broad-spectrum sunscreen with a sun protection factor (SPF) of 30 or greater (for UVB protection), zinc oxide (for UVA protection), and iron oxide (for visible and blue light) 20 minutes before sun exposure and every 2 hours thereafter, more if you are sweating or swimming. Check the label for directions.
  • Select clothing, cosmetic products, and contact lenses that offer UV protection.
  • Wear sunglasses with total UV protection and a wide-brimmed hat to shade your face and neck.
  • Avoid direct sun exposure as much as possible during peak UV radiation hours (between 10:00 a.m. and 2:00 p.m.). The UVA rays, which cause premature skin aging and initiate skin cancers, are out all day long.
  • Perform skin self-exams regularly (at least monthly) to become familiar with existing growths and to notice any changes or new growths.
  • Eighty percent of a person's lifetime sun exposure is acquired before age 18. As a parent, be a good role model and foster skin cancer prevention habits in your child.