35 Skin Cancers

Skin Cancer – What is it?

Skin cancer is the most common form of cancer, though is easily visible on the skin, making it easy to diagnose early and readily accessible to treat.  Most types of skin cancer have an excellent prognosis with most individuals being declared cancer-free after treatment.  However, malignant melanoma, although one of the more rare skin cancers, is the most deadly as it starts becoming malignant early, resulting in a high mortality rate. 

Skin Cancer – Risk Factors and Prevention Strategies

Exposure to UV is the most predominant risk factor for all skin cancers, meaning that avoiding sun exposure particularly when the high UV index is high is recommended.  UV can cause DNA mutations particularly in the tumor suppressor gene p53 that lead to a cell becoming cancerous.  Mutations in genes that regulate the rate of cell cycling and the rate of apoptosis can lead to a cell becoming cancerous (i.e., inappropriately continuing to divide without exiting the cell cycle to differentiate and inappropriately not being able to induce apoptosis, effectively, becoming an immortal cell that continually proliferates, spreading and negatively affecting healthy tissues).

It is important to apply sunscreen (SPF 30 or higher) when outside, as well as wearing a hat and sunglasses that offer UVA and UVB protection.  Remembering to re-apply sunscreen regularly if swimming or exercising or near reflective surfaces (i.e., water, snow, sand) is also important.  Exposure to other carcinogens (e.g., smoking, pollutants) increase one’s susceptibility to skin cancer.  Although anyone can get skin cancer, age, genetic susceptibility (including light skin colour), tanning beds, high-fat diet, alcohol consumption, human papilloma virus infections, and immunosuppression are also risk factors to be conscious of.

Skin Cancer – Signs and Symptoms

A monthly self-monitoring of all moles and freckles assessing for any change in ABCD (Asymmetry, Border, Colour, and Diameter) is highly recommended.

Skin Cancer – Diagnosis

Skin cancer are often first assessed by family doctors and specialists (e.g., dermatologists, oncologists).  A visual examination followed by biopsy and histology examination of cells under the microscope is used to confirm the diagnosis of skin cancer.

Skin Cancer – Treatment 

Often minimally invasive surgery (e.g., cryosurgery) is used to remove the skin cancer.  This may be followed by chemotherapy if there is a strong chance of metastasis.

Three Most Common Skin Cancers in Canada:

• 1. Basal cell carcinoma develops in the bottom layer (stratum basale) of the epidermis, which may make sense as this is where the epidermal stem cells.  Stem cells that go through the cell cycle frequently are more at risk for being negatively affected by UV-induced DNA mutations. Basal cell carcinoma is the most common type of skin cancer, affecting 80,000 Canadians annually.
  2. Squamous cell carcinoma develops when DNA mutations occur in squamous epithelial cells just above the basal level in the epidermis.  Squamous cell carcinoma affect more than 20,000 Canadians annually.
  3. Malignant melanoma arises within melanocytes in the stratum basale of the epidermis and affects more than 5,000 Canadians annually.