Melanoma: detection, prevention and warning signs to look out for

Dr. Shelia Wijayasinghe explains everything you need to know about the form of skin cancer.
January 19, 2022 1:39 p.m. EST

Melanoma is the most serious form of skin cancer. It occurs when something goes wrong in the melanin-producing cells that give color to your skin.

To emphasize important elements of detective, prevention and warning signs, Dr. Sheila Wijayasinghe shared everything you need to know about melanoma, and the types of changes to keep an eye out for on your body. Hear more of what she had to say in the video above!

What is melanoma?

Normally, skin cells develop in a controlled and orderly way — healthy, new cells push older cells toward the surface, where they die and eventually fall off. But when some cells develop DNA damage, new cells may begin to grow out of control and can eventually form a mass of cancerous cells. 

The cause is not always clear, but it's likely a combination of factors, including environmental and genetic. However, Dr. Sheila says the number one factor is exposure to ultraviolet (UV) radiation from the sun, and from tanning lamps and beds. It's an important discussion, as outcomes often depend on the stage of diagnosis and treatment. It is crucial to detect early to reduce the risk of spread and increase the survival rate.


Risk factors

As previously mentioned, UV exposure does seem to be a risk factor for melanoma (through sun exposure/tanning beds). If you live closer to the equator or at a higher elevation, you will also get more direct UV radiation. Here are some of the other major risk factors when it comes to melanoma:

  • One or more severe, blistering sunburns can also increase your risk of melanoma. A history of five or more severe sunburns in adolescence more than doubles the risk of developing melanoma. 
  • Having more than 50 ordinary moles on your body indicates an increased risk of melanoma.
  • Genetics: a family history of melanoma. If a close relative, such as a parent, child or sibling, has had melanoma, you have a greater chance of developing a melanoma, too.
  • People with weakened immune systems have an increased risk of melanoma and other skin cancers.
  • Having fair skin, or less pigment (melanin) in your skin means you have less protection from damaging UV radiation. If you have blond or red hair, light-coloured eyes, and freckle or sunburn easily, you're more likely to develop melanoma than someone with a darker complexion. 


Darker complexions

Skin cancers are less prevalent in nonwhite racial ethnic groups, but when they occur, they tend to be diagnosed at a later stage and, as a result, have a worse prognosis.

There is the assumption that melanin protects so less likely to use sunscreen and do skin checks. Doctors are also often primed to look for melanoma in fair skinned patients, but may not counsel about this risk with patients of colour, because the chance is smaller. Late detection, though, is problematic.

The places on the body where skin cancers tend to occur in people of colour are often in less sun-exposed, more out-of-the-way areas, which makes detection more difficult. For example, the most common location for melanoma in patients of color is the lower extremities, like the soles of the feet.



Normal moles are generally a uniform color such as tan, brown or black, with a distinct border separating the mole from your surrounding skin. They're oval or round and usually smaller than 1/4 inch (about six millimeters) in diameter — the size of a pencil eraser. Most moles begin appearing in childhood, and new moles may form until about age 40. By the time they are adults, most people have between 10 and 40 moles. Moles may change in appearance over time and some may even disappear with age.


Warning signs

Skin cancers can develop anywhere on your body, but most often develop in areas that have had exposure to the sun, such as your back, legs, arms and face.

A good rule of thumb to use when looking at skin and changes is the ABCDEs - and this applies to melanoma but also other types of skin cancer (basal cell and squamous cell):

  • Asymmetry 
  • Border irregularity
  • Color variation
  • Diameter (more than 6 millimeters)
  • Evolution (a history of change in size, colour or shape)

Also - if you have a skin lesion that doesn’t heal well, or a mole that recurrently bleeds or never heals - this should alert you to seek out medical  attention.

It's also important to note that melanoma doesn't always begin as a mole. It can also occur on otherwise normal-appearing skin.



Here are some ways to lower your risk of melanoma:

  1. Reduce exposure to UV radiation (sunbathing, tanning beds), and using sun protection is key. If you'll be having intense sun exposure, wear hats, sunglasses protective clothing, and try to reduce sun exposure - especially during the 10-4 hours. Have caution near reflective surfaces like water, snow and sand - make sure to wear sunblock in the winter!
  2. Use SPF of at least 30 or higher. Make sure it's water resistant, and provides broad-spectrum coverage (protects against UVA and UVB rays). People of colour also need to use sunscreen.
  3. Monthly self-examinations. Make sure to look at the soles of your feet, palms, nail beds and genital areas.
  4. Take pictures of your moles, especially on hard to see places like your back. Have a friend/family member take a look at your back if it's difficult for you. If you see any change, take note and seek care, especially if you notice something unusual.


The information provided on the show is for general information purposes only. If you have a health problem, medical emergency, or a general health question, you should contact a physician or other qualified health care provider for consultation, diagnosis and/or treatment. Under no circumstances should you attempt self-diagnosis or treatment based on anything you have seen on the show.