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Skin Cancer—Overview

(Basal Cell Carcinoma; Squamous Cell Carcinoma)

En Español (Spanish Version)

Definition | Causes | Risk Factors | Symptoms | Diagnosis | Treatment | Prevention


Skin cancer is when cancer cells grow in the skin.

The two most common kinds of skin cancer are:

  • Basal cell carcinoma —This is the most common type of skin cancer. Basal cell carcinoma develops in the outermost layer of skin. This cancer usually grows slowly and does not spread to other tissues in the body.
  • Squamous cell carcinoma —This cancer develops in the uppermost layer of skin cells. Squamous cell carcinoma usually grows slowly. However, in some cases it can grow fast and spread to other tissues in the body. If treated early this type of cancer is rarely fatal. However, the cancer can be fatal if it spreads beyond the skin.

Basal Cell Carcinoma

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It is important that skin cancers be found and treated early. If left untreated, they can quickly invade and destroy nearby tissue.


Cancer occurs when skin cells in the body divide without control or order. When cells keep dividing uncontrollably when new cells are not needed, a mass of tissue forms. This is called a growth or tumor. Unlike benign tumors, malignant tumors can invade nearby tissues and spread to other parts of the body.

Risk Factors

Basal and squamous cell cancers are more common in men and in people over 50 years old. These cancers are most likely to occur in people with:

  • Fair skin that freckles easily
  • Red or blonde hair
  • Light-colored eyes
  • Caucasian skin

Other factors that increase your risk of skin cancer include:

  • Personal history of skin cancer
  • Exposure to ultraviolet radiation from the sun or artificial radiation from a tanning bed
  • Excessive sun exposure without protective clothing or sunscreen
  • Skin damage from burns or infections
  • Exposure to arsenic, industrial tar, coal, paraffin, and certain types of oil
  • Radiation therapy treatment
  • Light treatments for psoriasis, especially psoralen ultraviolet A (PUVA)
  • Having a weak immune system due to illness or medications
  • Certain genetic diseases, such as basal cell nevus syndrome or xeroderma pigmentosum


Most skin cancers do not cause symptoms. The most common first symptom of skin cancer is a change in the skin.

Basal cell carcinoma may appear as a:

  • Slowly expanding, painless growth
  • Bleeding scab or sore that heals and recurs
  • Flat, firm, pale area
  • Small, raised, pink, red, shy, or pearly areas thay may bleed easily
  • Large oozing, crusted area

Squamous cell carcinoma may appear as a:

  • Growing lumps with rough, scaly, or crusted surfaces
  • Slow-growing flat, reddish patches in the skin
  • Recurrent, nonhealing ulceration or bleeding

Skin cancers can occur anywhere, but are more common on places that are exposed to the sun.


Your doctor will ask about your symptoms and medical history. A physical exam will be done.

You may have a biopsy. The sample can then be examined for cancer cells.

In cases where the growth is very large, or has been present for a long time, the doctor will carefully check the lymph nodes in the area. Your doctor may recommend more tests to determine if the cancer has spread to other parts of the body.


Talk to your doctor about the best treatment for you. Treatment may include one or more of the following:

Many skin cancers can be cut from the skin quickly and easily. In fact, the cancer is sometimes completely removed during biopsy, and no further treatment is needed. Surgical techniques include:

This involves scooping the cancer out with a curette, an instrument with a sharp, spoon-shaped end. The area is treated with an electric current to control bleeding. This also kills any cancer cells remaining around the edge of the wound. This technique is used for very small or superficial cancers.

Mohs surgery is the removal of all of the cancerous tissue. The surgeon will try to remove as little healthy tissue as possible. This method is used to remove:

  • Large tumors
  • Tumors in hard-to-treat places
  • Tumors of undetermined shape and depth
  • Cancers that have recurred

The procedure is done by specially trained dermatologic Mohs surgeons. The cancer is shaved off one thin layer at a time. Each layer is checked under a microscope for cancer cells until the entire tumor is removed.

Liquid nitrogen is used to freeze and kill the abnormal cells. After the area thaws, the dead tissue falls off. More than one freezing may be needed to remove the growth completely. This method may be used to treat precancerous skin conditions (actinic keratoses) and certain small or superficial skin cancers.

Laser therapy uses a narrow beam of light to remove or destroy cancer cells. This method is sometimes used for cancers in the outer layer of skin.

Radiation therapy uses radiation to kill cancer cells and shrink tumors.

Topical chemotherapy is the use of drugs to kill cancer cells. The drugs can be creams or lotions. This method is successful in treating precancerous conditions and cancers limited to the outer layer of the skin. The most common topical chemotherapy used is a form of 5-fluorouracil (5-FU) .

Medicines such as imiquimod increase your bodies own reponse to fight the cancer cells.


  • Avoid spending too much time in the sun.
  • Protect your skin from the sun with clothing. Wear a shirt, sunglasses, and a hat with a broad brim.
  • Use sunscreens with a sun protection factor (SPF) of 15 or more on skin that will be exposed to the sun .
  • Avoid exposing your skin to the sun between 10:00 AM and 2:00 PM standard time, or 11:00 AM to 3:00 PM daylight saving time.
  • Don't use sun lamps or tanning booths.

Take the following precautions to find skin cancer early:

  • If you have any of the symptoms listed above, have your skin examined by a doctor.
  • If you have fair skin, have your skin checked by a doctor.
  • Learn how to do a skin self-exam .

American Academy of Dermatology


American Cancer Society



Canadian Cancer Society


Canadian Dermatology Association



Basal cell carcinoma of the skin. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/what. Updated January 17, 2013. Accessed April 10, 2013.

Skin cancer: basal and squamous cell. American Cancer Society website. Available at: http://www.cancer.org/acs/groups/cid/documents/webcontent/003139-pdf.pdf. Updated January 17, 2013. Accessed April 10, 2013.

Skin cancer. National Cancer Institute website. Available at: http://www.cancer.gov/cancertopics/types/skin. Accessed April 10, 2013.

Squamous cell carcinoma. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/what. Updated december 6, 2013. Accessed April 10, 2013.

Last reviewed June 2013 by Mohei Abouzied, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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