Skin Cancer

Skin Cancer

Skin cancer is very common, probably because most people exposed themselves to sunlight to tan the skin. Some continue to do so, despite the risks.

There are mainly two types of skin cancer: nonmelanoma and melanoma. Skin cancer that forms in melanocytes (skin cells that make pigment) is called melanoma. The other forms of skin cancers are non-melanoma, which mostly include the carcinomas.

Skin is composed of three layers: outer epidermis, dermis and subcutaneous tissue. The epidermis is the original site of carcinoma in skin. Carcinoma in skin can be of various types depending on its site of origin. If the cancer begins in the round basal cells of lower part of epidermis, it is called basal cell carcinoma. The other major form of carcinoma is the squamous cell carcinoma, which involves the flat squamous cells. There are a few very rare other types of nonmelanoma skin cancers.

Epidemiology

Nonmelanoma skin cancers (NMSCs) account for more than one-third of all cancers in the United States. Around 3.5 million cases of NMSC are found every year in the United States. Among them, 8 out of 10 are basal cell carcinomas (BCCs) and 2 out of 10 are squamous cell carcinomas.

Skin cancer is exceedingly common and the incidence is rising rapidly. The mortality rate for nonmelanoma skin cancer (NMSC) is decreasing. But, the number of deaths is still quite high. Ozone depletion has contributed to rising incidence rates of NMSC. People of all ages can get skin cancer, but it is rare in children. Symptoms and treatment depend on the type of cancer. Current estimates are that one in five Americans will develop skin cancer in their lifetime. NMSCs are the most common malignancies occurring in the white populations each year. The incidence of NMSC is 18–20 times higher than that of malignant melanoma.

Types of skin cancer

Skin cancer can be of the following types

  • Squamous Cell Carcinoma: It develops mostly on areas of the skin exposed to the sun, like ears, the face and the mouth.
  • Basal Cell Carcinoma: These are found to develop on the face, neck, and hands and rarely spreads. It is the most common skin cancer accounting for more than 75% of skin cancers diagnosed. It rarely metastasizes or kills.
  • Melanoma: Melanoma can develop on any part of the body; however, it develops more on the arms, legs and trunk. It is the most dangerous and deadly type of skin cancer.

Types of skin carcinoma

Major types of Basal cell carcinoma (BCC)

A simple classification of basal-cell carcinoma into 3 groups, based on location and difficulty of therapy:

  • Superficial basal-cell carcinoma: This carcinoma is considered as “in-situ.” Chemotherapy with Aldara or Fluorouracil is the standard treatment.
  • Infiltrative basal-cell carcinoma: It is aggressive and infiltrates in the deeper layers of the skin. Curettage is not good enough for treating this type of BCC.
  • Nodular basal-cell carcinoma: It encompasses most of the remaining categories of basal-cell cancer. It is also called classic basal cell carcinoma. The nodules are round or oval in shape and are translucent with small blood vessels over it.

Major types of Squamous cell carcinoma (SCC)

  • Actinic keratoses. They are very similar to well differentiated SCC in appearance and can be differentiated only by biopsy. They are not at all dangerous at an early stage, but can become cancerous. Cryotherapy is frequently recommended. For some thicker lesions, curettage is used. Creams like 5-fluorouracil can also be used, especially if there are multiple spots.
  • In-situ SCC: This is the mildest type and very much curable. It appears as a thick scaly red rash. The tumor remains in the outer skin layer. Treatment can be done with creams such as 5 Fluorouracil or by curettage. Surgery is not needed usually.
  • Well-differentiated SCC. This is the most usual type and appears as very thick crusty lesions on the skin. The deeper layers of the skin (dermis) are invaded and may have spread to other parts. Surgical removal of the affected part is the common treatment. Creams do not help. Even after surgery, risk of spreading of cancer remains. Therefore, frequent check-ups are recommended.

Symptoms of BCC and SCC

These cancers frequently do not cause symptoms unless they are large, at which point they may cause pain or bleeding.

Symptoms of Basal Cell Carcinoma:

  • A shiny, pearly nodule
  • A red patch (superficial)
  • Skin thickening or scar tissue (yellow or white area) (infiltrative)
  • A sore that oozes or bleeds

Symptoms of Squamous Cell Carcinoma:

  • An open sore (ulceration, reddish, flat spot that is sometimes crusty)
  • Sore that gets larger and a sore that won’t heal
  • Intermittent bleeding
  • A hard opalescent plaque

Risk factors for BCC and SCC

  • Light-colored skin: people with fair skin are at more risk; they have less melanin-containing cells to protect them.
  • Sun exposure: Intermittent sun exposure or other source of ultraviolet light like tanning booths. The more exposure and the greater number of sunburns, the greater the risk. Patients with psoriasis treated with ultraviolet light may also be at more risk.
  • Age: Incidence of BCC increases with age; mostly detected after 50.
  • Sex: More men than women have skin cancer.
  • Previous skin cancer: This increases your risk for another cancer.
  • Therapeutic radiation: When radiation is given for other cancer treatment skin cancer may develop.
  • Scars or other significant skin injury: Cancer can develop in the scars.
  • Immunosuppression: Suppression of immunity by medication or disease has been linked to cancer in some cases.

There are also some factors like smoking and HPV infection that may increase the risk of skin cancer. There is also a rare condition called Gorlin syndrome which causes basal cell cancers.

Diagnosis of Skin carcinoma:

  • Physical exam: Doctors can examine the affected part of the skin visually. They can assess the lesion of the skin and decide if cancer is likely and biopsy or removal necessary.
  • Biopsy: The question of malignancy and cell type of a lesion is often in doubt. Therefore biopsy should be performed by removing a part of the tissue from the affected region. There are different kinds of biopsies. A sample of a large lesion can be taken, or the entire area may be removed at the same time as the biopsy.

Treatment

  • Surgical excision: This can be performed for both BCC and SCC. It is the most effective treatment.
  • Curettage with electrocautery: It can be used for both BCC and SCC. The technique includes scooping out the carcinoma by using a spoon -like instrument called a curette. Desiccation is the additional application of an electric current to control bleeding and kill the remaining cancer cells. The skin heals even without stitching.
  • Cryotherapy: Liquid nitrogen is used to freeze the section and then removed. Recurrence rate is higher than surgery. It can be used for both forms of carcinoma.
  • Laser destruction: Laser beam can be used to destroy skin carcinoma. But, recurrence rate is higher than cryotherapy.
  • Mohs micrographic surgery: Large, aggressive, recurrent or location-sensitive BCC and SCC can be cured by this treatment. This process involves a layer by layer removal of the tumor while examining cells of each layer under microscope. This method removes as little of the healthy normal tissue as possible. Cure rate is very high, exceeding 98%. If large amounts of tissue need to be removed, the surgeon sometimes works with a plastic (reconstructive) surgeon to achieve the best possible postsurgical appearance.
  • Chemotherapy: Creams or lotions containing anti-cancer agents, such as 5-fluorouracil, Efudex and Fluoroplex can be directly applied on the skin for very superficial cancers. These drugs may cause inflammation and scar formation. Imiquimod (Aldarais another medicine can also be applied in skin. It is used to treat superficial basal cell carcinoma in adults with normal immune systems. It can be also used for SCC at an early stage.

Prognosis

  • Superficial skin cancers are usually cured by simple surgery alone. In the majority of cases of BCC, cure is possible. The rate of BCC recurrence is about 1% with Mohs surgery, and up to 10% for other forms of treatment. It rarely spreads. Therefore, the prognosis for BCC is very good.
  • When a SCC is detected early, the prognosis is excellent, but it depends on the stage if detected late. Most (95%) of squamous cell tumors can be cured if they are removed promptly. Recurrence may occur, therefore proper follow-up is required. Chances of spreading to other organs are less than 1%.

References

  1. Kwasniak LA, Garcia-Zuazaga J. (2011) Basal cell carcinoma: evidence-based medicine and review of treatment modalities. Int J Dermatol.;50(6):645-58.
  2. Samarasinghe V, Madan V, Lear JT. (2011) Management of high-risk squamous cell carcinoma of the skin. Expert Rev Anticancer Ther.;11(5):763-9.
  3. Hulyalkar R, Rakkhit T, Garcia-Zuazaga J. (2011) The role of radiation therapy in the management of skin cancers. Dermatol Clin.;29(2):287-96.
  4. T.L. Diepgen and V. Mahler (2002) The epidemiology of skin cancer. British Journal of Dermatology; 146 (Suppl. 61): 1–6.
  5. Gloster HM Jr, Brodland DG. (1996) The epidemiology of skin cancer. Dermatol Surg. ;22(3):217-26.
  6. This article was originally published on September 3, 2012 and last revision and update was 9/4/2015.