What changes in the skin occur due to exposure to the sun?

Many people love the sun. The sun's rays make us feel good, and in the short term, it makes 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 her 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 can actually mean accelerated effects of aging and an increased 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 breakdown, 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 in addition to 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.

Changes in the skin related to sun exposure:

  • Precancerous (actinic keratosis) and cancerous (basal cell carcinoma, squamous cell carcinoma, and melanoma) skin lesions caused by loss of 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 tissue causing lines and wrinkles

What is skin cancer?

Skin cancer is the most common form of cancer in the US, and the number of cases continues to rise. It is the uncontrolled growth of abnormal skin cells. While healthy cells grow and divide in an orderly way, cancer cells grow and divide in a rapid, haphazard manner. This rapid growth results in tumors that are either benign (noncancerous) or malignant (cancerous).

There are three main types of skin cancer:

  • Basal cell carcinoma
  • Squamous cell carcinoma
  • 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.

What causes skin cancer?

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.

Cumulative sun exposure causes mainly basal cell and squamous cell skin cancer, while episodes of severe blistering sunburns, usually before age 18, can cause melanoma later in life. Other less common causes are repeated X-ray exposure, scars from burns or disease, and occupational exposure to certain chemicals.

Who is at risk for skin cancer?

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 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 of large and irregularly shaped moles are risk factors unique to melanoma.

What are the signs and symptoms of skin cancer?

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 and neck; or as a flat, pink/red- or brown-colored 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 itch, 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. It may resemble a normal mole, but usually has a more irregular appearance.

When looking for melanoma, think of the ABCD 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 6 mm)