December 16, 2018
Dermatologist examining patient

Skin Cancer: Causes and Treatments

by Berkeley Wellness  

Skin cancer is the most common of all cancers. The skin changes that result in cancer develop cumulatively and irreversibly in an individual over the years, and so may take decades to produce a malignancy. Men get skin cancer more frequently than women, and it usually shows up in older people, but no one is exempt. In fact, Americans are developing skin cancer at ever-younger ages because of the increasing amounts of time spent in the sun (as well as time spent in indoor tanning booths).

Prolonged sun exposure is the principal cause of skin cancer. Exposure to the sun’s ultraviolet radiation is known to promote three kinds of skin cancer. Basal cell carcinoma is the most prevalent type. The most common site for basal cell carcinoma is the face, especially the nose or ears, but it can appear anywhere. It is painless and slow-growing, and rarely spreads to other parts of the body.

Squamous cell carcinoma typically develops on the face, lips, nose, the rim of the ear, and the back of the hands but can also appear elsewhere. If not treated, the lesions can grow and spread to other parts of the body, including internal organs, although this is rare. Squamous cell carcinoma is often preceded by precancerous lesions called actinic ketatoses.

5.4 million basal and squamous cell skin cancers are diagnosed each year in the U.S. The majority—8 of 10—of these are basal cell. Fortunately, both basal cell and squamous cell skin cancers have a 95-percent cure rate when detected and treated early.

Melanoma is the least common of the three, with an estimated 87,000 new cases diagnosed in the U.S. per year. It is also the most dangerous, though early treatment can result in a cure. Melanoma develops from melanocytes—cells located in the epidermis that produce melanin, the dark pigment that helps protect the skin from ultraviolet radiation. Melanocytes are scattered throughout the epidermis and can also collect and form benign moles, or nevi. Melanoma occurs when melanocytes begin reproducing uncontrollably to form malignant tumors.

Once rare, the incidence of melanoma in the U.S. has increased dramaticallyin the last 40 years. Since 1973 the number of melanoma cases per year has doubled even as the use of sunscreen has increased. During this same time period, the mortality rate for melanoma increased slowly until 10 years ago, after which point it has remained stable. And whereas melanoma was once a disease of the aging, now 25 percent of all cases of melanoma are in people under 45 years old.

Many scientists attribute some of this increase to the gradual destruction of the stratospheric ozone layer, which is allowing more ultraviolet radiation to reach the earth’s surface.

Signs and symptoms of melanoma

General signs

  • Any change in the size, color, shape or texture of a mole or other skin growth.
  • An open or inflamed wound that won’t heal.
  • Any new spot on the skin.

Signs of basal cell carcinoma

  • A sore that doesn’t heal. Have it checked if it hasn’t healed after three weeks and it crusts, bleeds, or oozes.
  • A persistent reddish patch. It may be painful or may crust and itch; or it may not bother you at all.
  • A smooth bump indented in the middle. The borders will be rolled, and as it grows you may notice blood vessels on the surface.
  • A shiny, waxy, scarlike spot. It may be yellow or white with irregular borders.

Signs of squamous cell carcinoma

  • Small, firm lump or patch, initially painless, that develops on the face or back of the hand. May be raised or flat, with a scaly or crusted surface.
  • Slowly grows to take on a wartlike appearance; may become painful.

Signs of malignant melanoma

  • A mole that begins to enlarge, thicken, or change color. (Some 70 percent of early-stage lesions are identified because of recent changes in size, color, border contours, or surface texture.)
  • A mole that suddenly begins to grow, or one that bleeds or ulcerates.
  • A mole that has irregular rather than round borders.
  • A mole with irregular pigmentation—some portions light colored, others almost black.

What causes skin cancer?

It is clear that the risk of basal and squamous cell carcinoma rises in proportion to the cumulative amount of time people have spent in the sun. But the sun’s role in the development of melanoma is less clear, and in fact surprisingly little is known about what causes melanoma. People who spend lots of time in the sun (such as farmers) do not have elevated rates of melanoma, though they do have higher rates of squamous and basal cell carcinoma. And melanoma often turns up on parts of the body rarely exposed to the sun (such as the buttocks and soles of the feet).

Genetic factors—including those that affect skin and hair color and the type and number of moles—clearly play a role. But genetics can’t explain the huge increase in melanoma incidence over the past three generations. There's evidencethat intermittent sun exposure and severe, blistering sunburns, especially early in life, rather than simply years of sun exposure, cause melanoma. However, studies have been inconsistent about the role of sunburn.

The people at highest risk for melanoma are fair-skinned—notably people with red or blonde hair, who freckle (especially on the upper back), or who have rough red patches on their skin (actinic keratoses) as a result of spending time in the sun. If, in addition, you have a family history of melanoma or have had three or more blistering sunburns as a child or teenager, your risk also increases.

What if you do nothing?

If untreated, all these forms of skin cancer will ultimately become destructive. Basal cell carcinomas are slow-growing, but it is important that they be found and treated early because they can ultimately invade and destroy nearby tissues. Melanoma that goes untreated may spread to other parts of the body, which is why it is the most dangerous form of skin cancer. Though melanoma is the least common type of skin cancer, accounting for about 1 percent of all cases, it accounts for the vast majority of deaths from skin cancer.

Are there any home remedies for skin cancer?

No. Skin cancer requires evaluation and treatment by a physician.

How to prevent skin cancer

Even if the only risk factor you have is fair skin, you still need to be cautious and to protect yourself. One of the major steps you can take to prevent all forms of skin cancer is to reduce your direct exposure to sunlight, consistently use a broad-spectrum sunscreen of SPF 15 or higher, and wear protective clothing.

When to call your doctor

Contact your doctor if you develop any of the symptoms listed above. Any new growths, changes in the size or color of existing growths, any sore that doesn’t heal, or any persistent patch of irritated skin are reasons to see your doctor.

If you have had skin cancer, you should be sure to have your skin checked regularly.

What your doctor will do

Your doctor (or a dermatologist) may perform a biopsy—that is, remove all or part of a growth that doesn’t appear normal. To check for cancer, this sample of tissue is examined under a microscope to detect cancerous cells. Dermatologists may be better than primary care physicians at detecting melanomas.

If cancer is detected, the doctor will determine what stage it is in: local (affecting only the skin) or metastatic (spreading beyond the skin). You may need to have additional tests, such as x-rays, to find out whether cancer has spread to other parts of the body and to help plan the best treatment.

When caught in time, basal cell carcinoma can often be removed by a doctor on an outpatient basis, leaving only a minor scar. Once malignant melanoma is detected, you should see a doctor with special expertise in melanomas. The treatment is prompt surgical removal.

The 5-year survival rate for all stages of melanoma is 92 percent; the 10-year rate is 89 percent. If the melanoma is removed in the later stage, when a tumor has begun to invade the surrounding tissues or other areas of the body, the survival rate drops sharply compared with when melanoma is removed in the early stages.