Melanoma: Your Need-to-Know Guide to the Causes, Symptoms and How to Detect It Early


With summer in full swing it’s only natural to want to spend as much time as possible feeling the sun on your skin. But before you head into the fresh air, check out our resource for your need-to-know facts about the most dangerous form of skin cancer, melanoma. Here we break down the info (using scientific sources) on what you can do to prevent putting yourself at risk, and how to recognize the symptoms before the disease spreads. The number one thing we want you to know: when recognized and treated early, melanoma is almost always curable.  

What is Melanoma?

Melanoma is a malignant type of cancer that starts in the melanocytes – melanin producing cells that give your skin and eyes their colour1. Melanoma usually starts on the skin when melanocytes change and become abnormal to cause precancerous conditions, meaning that the cells are not yet cancer, but have a higher chance that these abnormal changes will become cancer2. Once these changes occur, they can trigger mutations that lead the skin cells to multiply rapidly and form malignant tumours3. These abnormal changes often present themselves superficially as an atypical mole, or dysplastic nevus (our tips for how to recognize this below). Melanoma has the ability to start in other parts of the body beyond the skin where melanocytes are found such as internal organs or in mucus tissues, but these types are extremely rare.

Melanoma is the most dangerous form of skin cancer characterized by its ability to spread, or metastasize, to other organs by travelling through the bloodstream or lymphatic system4. It is also treatable and curable when caught early on. Knowing the causes of melanoma, if you are at risk, how to protect yourself and how to spot a potentially cancerous mole can significantly lower your risk of developing advanced stage melanoma.

What Causes Melanoma and am I at Risk?

Like most cancers, the exact cause of malignant melanoma is not clear but a large number of studies have indicated that risk correlates with genetic and personal characteristics, and a person’s exposure to UV rays.  The World Health Organization has identified and detailed the main risk factors explained below:

  • A large number of atypical moles (typically between 50 to 100) is the most significant risk factor for fair-skinned populations.
  • Malignant melanoma is more prevalent among people with a pale complexion, blue eyes and red or fair hair.
  • High, intermittent exposure to solar UV appears to increase risk.
  • A family history of melanoma in a close relative - such as a parent, child or sibling - gives you a higher chance.
  • Several epidemiological studies support a positive association with history of sunburn, in particular ones occurring at an early age.
  • The connection between cumulative sun exposure and malignant melanoma is inconclusive, but the risk is higher in people with a history of non-melanoma skin cancers and solar keratoses, which are both directly related to cumulative UV exposure5.

While the incidence of malignant melanoma is on the rise, just because you identify with one or more of these risk factors does not mean a diagnosis is inevitable. Rather, there are multiple steps and precautions you can take to protect yourself and to identify potentially dangerous symptoms of melanoma before an advanced stage is reached.

Prevention Through Protection

The single greatest way to decrease your chances of developing any kind of skin cancer or damage is to monitor your sun exposure. The Sun Wise School Program, developed by the United States Environmental Protection Agency, advises these steps for protecting yourself from harmful rays:

Limit time in the midday sun

    The sun’s rays are strongest between 10 a.m. and 4 p.m., when possible schedule outdoor activities before or after these hours.

    Watch the UV index

      Take special note of sun safety when the UV index predicts exposure levels of moderate or above.

      Find shade

        Take note of the shadow rule: “Short shadow, seek shade!” And remember, trees, umbrellas or canopies do not offer complete sun protection.

        Wear protective clothing

          Add tightly woven, loose fitting clothing to your wardrobe and grab a hat with a wide brim to protect eyes, ears, face and the back of your neck. Look for sunglasses that provide 99 to 100 percent UV-A and UV-B protection as your eyes are as much at risk as your skin for melanoma.

          Use sunscreen

            Apply sunscreen often and liberally. Check out our full guide to choosing the right one for you here.

            Never fake tan

              This one should go without saying but a direct correlation has been proven between sunbeds and malignant melanoma. Avoid sunlamps and tanning parlours at all costs.6

              Know the Symptoms of Melanoma

              Moles are extremely common with the average person having between 10 and 40 on their body, and those with a higher risk factor having over 50. A normal mole is round or oval, flesh-coloured, pink, tan or brown and flat or dome-shaped. Melanomas can start with a change in normal-looking skin, or develop from an existing mole, freckle, birthmark or coloured spot that can occur over several months to years7. Cancerous spots are most common on the backs of men and on the legs of women.

              Given the amount of moles on a body, and the various ways a melanoma can present itself, it can sound very daunting to keep track of potentially harmful spots. But considering what is on the line, it’s important to examine your skin on a regular basis, preferably performing self examinations at least monthly. If you have over 50 moles, it is advised that checks are done annually by a professional, preferably a dermatologist who can document any changes to suspicious moles over time. To aid in these body once-overs, the ABCDEs of early detection were developed to help determine if a doctor should be consulted. Review the basics below and check out this guide from the Canadian Skin Cancer Foundation for visual cues.

              The ABCDEs of Melanoma

              • Asymmetry: First check a mole by its shape, if both halves look the same it is symmetrical and healthy. Asymmetrical moles are abnormal and have sides that differ from one another. If you’re not sure, draw a line down the middle and compare.
              • Border: Look over the edges. If they are smooth the mole is healthy, if they are uneven it could be cancerous.
              • Colour: Moles should be one monotone colour. If a mole has various shades of brown, it could be cancerous.
              • Diameter: The general rule to live by is if the mole is larger than an eraser on the end of a pencil (about 6mm) then it is suspicious. This doesn’t mean skin cancers can’t be smaller than that though, always keep an eye out for other indicators.
              • Evolution: Watch for changes to the mole over time. This can be change in size, colour or shape. Other symptoms include itching, tenderness or bleeding. If you suspect changes are occurring, monitor the mole every month tracking any differences you notice. Don’t hesitate to take pictures!8

              Protecting and preventing damage to your largest organ can feel like a full time job, but with great work comes great reward and the benefits of both knowing your risk and monitoring potential symptoms are endless when it comes to melanoma.


              1. Canadian Cancer Society (2017) What is melanoma? Retrieved from

              2. Canadian Cancer Society (2017) What is melanoma? Retrieved from

              3. Skin Cancer Foundation (2017) What Is Melanoma? Retrieved from

              4. Sunnybrook Health Sciences Centre (2017) About melanoma. Retrieved from

              5. World Health Organization (2017) Health effects of UV Radiation. Retrieved from

              6. United States Environmental Protection Agency (2017) Sun Safety. Retrieved from

              7. Canadian Cancer Society (2017) Signs and symptoms of melanoma. Retrieved from

              8. Canadian Skin Cancer Foundation (2017) Early Detection. Retrieved from

              1. What is Melanoma?
              2. What Causes Melanoma and am I at Risk?
              3. Prevention Through Protection
              4. Know the Symptoms of Melanoma
              5. The ABCDEs of Melanoma