Skin cancer: types, causes, treatment, and prevention

Skin cancer is the most common form of cancer. Like other forms of the disease, it’s the result of an abnormal and uncontrollable growth of cells, but in your skin. The most common places to get skin cancer are on your face or other areas that see lots of sun. Skin cancer on your ear or nose, for example, is more common than you might think.

Thankfully, skin cancer also has some of the best survival rates, and is the most preventable form of cancer. Here’s how to spot the first signs of the disease, and how to prevent it in the first place.

What causes skin cancer?

Ultraviolet (UV) light is the main underlying cause of skin cancer. This makes sun exposure the number one factor in developing it. Genetics also play a role, however, as a family history of the disease increases your chances of developing it. Finally, exposure to certain substances and chemicals, such as pesticides and insecticides, likely influence the development of the disease.

Who’s at risk for skin cancer?

The short answer is everyone, since UV exposure from the sun is the biggest cause of skin cancer. Not everyone, however, has the same risk of developing the disease.

The following factors may increase your risk of melanoma and other skin cancers:

Excessive sun exposure
Living at a higher elevation or in a warmer climate
Using tanning beds — especially before age 35
Not wearing sunscreen
A personal or family history of skin cancer
Having fair, sun-sensitive skin that burns instead of tans
Having blond or red hair
A history of sunburns, especially as a child
Having blue or green eyes
Having more than 50 moles, especially unusual ones
Working outdoors

Is all skin cancer melanoma?

No. Melanoma of the skin — also called cutaneous melanoma — is only one specific type of skin cancer. There are different types of melanoma, including superficial spreading melanoma — the most common type of melanoma — and nodular melanoma. The vast majority of skin cancers, however, are non-melanoma skin cancers.

How aggressive are skin cancers and are they curable?

Non-melanoma skin cancers are the most common form of cancer. How frequently they occur is only a guesstimate, however, because patients don’t usually require hospitalization.

Non-melanoma skin cancers are usually slow-growing, very curable, and easily removed at a dermatologist’s office.

Melanoma is another form of skin cancer and is usually quite treatable when detected early. In its later stages though, melanoma can be very aggressive and progress quickly. Most deaths from skin cancer are due to melanoma.

What are the different types of skin cancer?

There are a few different types of skin cancer, but basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) are the most common non-melanoma skin cancers. Melanoma may be the most well-known of the skin cancers, as it’s the most aggressive type.

What are the early signs of skin cancer?

Early signs of skin cancer typically involve a change to a specific area of your skin. This could be a new growth, or a change in an existing mole. And there isn’t just one type of mole either. Moles can be with you from the day you’re born, or pop up throughout your life. The three types of moles are:

Congenital moles – moles that are present from birth, are round or oval on the skin, and may be slightly raised.
Atypical moles – also known as dysplastic moles, they’re present from birth but differ in shape from congenital moles. Instead of being round or oval, their perimeter is uneven.
Acquired moles – moles that appear after birth and are small and circular with a fairly even shape.

Before you go worrying about every new or existing mole though, there are specific signs to look out for.

The early signs of skin cancer depend on which type it is. BCC, for example, often appears as a reddish patch or an open sore that isn’t healing. It can also emerge as a shiny, round bump, or as a nodule that’s either the colour of your skin, pink, or red. Alternatively, it may show up as a white, waxy, or yellow scar-like area, or as a small pink growth with a crusted center.

SCC may take shape as a wart-like growth. It’s often pink or red with irregular borders, although it can also appear as an open sore or a red, scaly patch. Like BCC, SCC may bleed, ooze, or have a crust.

Melanoma is a little different from SCC and BCC, as it may look like a new mole, or develop on an existing one. Early signs of melanoma include a change in the colour, shape, or size of a mole, or the appearance of a new mole with certain characteristics.

When doing a self-exam, look out for the ABCDEFs of your moles:

Asymmetry — is one side of your mole noticeably different from the other?
Border — are the edges of your mole ragged or blurry?
Colour — is your mole more than one colour?
Diameter — is your mole larger than a pencil eraser?
Evolving — does it seem like your mole is changing shape or growing?
Firmness — is your mole firm, solid, and doesn’t flatten when you press it?

Beyond monitoring the ABCDEFs, the Canadian Dermatology Association also recommends comparing your moles. If one stands out and looks totally different from the moles around it — also known as “the ugly duckling sign”— it may be worth checking out.

What are the different stages of skin cancer?

Because non-melanoma skin cancers are usually quite treatable, doctors don’t tend to use stages to describe them. Instead, they categorize BCC and SCC as either low-risk or high-risk.

A low-risk BCC is one that’s less than 2cm wide and isn’t on the eyelids, nose, ears, or skin around the eyes. Its edges are smooth, and it hasn’t spread to any surrounding nerves.

A high-risk BCC is larger than 2cm or has developed on the nose, ears, skin around the eyes, or on one of the eyelids. It may also have ragged edges or have spread into or around the nerves.

A BCC is also considered high-risk if it’s cancer that has returned to the same spot, or if it’s an aggressive form of the disease.

An SCC is tagged as either high-risk or low-risk based on many of the same criteria, with the addition that one on the lips or scalp is also deemed high-risk.

While both BCC and SCC are usually quite treatable, SCC can become more invasive, destroying neighbouring tissue, and sometimes spreading to other sites in the body.

The stages of melanoma

When it comes to melanoma, doctors break down the cancer into five stages of development. Each stage corresponds to the size of the growth, and whether or not it has spread to other places in the body.

In stages 0 through II, the melanoma is about 4mm — around the size of a pencil eraser — or smaller, and hasn’t spread to any of the surrounding tissue.

Stage III melanoma is when you begin to have spread, or metastization of the cancer. It may spread to surrounding lymph nodes in the body, or to areas on the skin 2cm or more from the initial lesion. This stage has a variety of subgroupings, depending on the degree of spread.

Stage IV melanoma is the most serious stage of the disease. At this point, it has spread to other parts of the body and has affected organs such as the brain, liver, and lungs. Stage IV melanoma is difficult to treat, but a percentage of those experiencing it does respond to treatment.

Different stages of melanoma

How long does it take for skin cancer to spread?

Different types of cancer grow at different rates — non-melanoma skin cancers, for example, are typically slow-growing. They still require treatment, however, as they can spread to other areas of the body. This may eventually cause other health issues and even death.

Melanoma, on the other hand, can grow and metastasize very quickly. How fast melanoma spreads depends on a number of factors including the type of melanoma, the location and size of the tumour, and your medical history.

Early-stage treatments for skin cancer

Removing the growth is the first line of skin cancer treatment. Surgical excision is most common, but there are many other options that can be used alone or in combination with others. Dermatologists typically perform these procedures in their offices using a local anesthetic, including:

Surgical excision — in this technique, the doctor uses a scalpel to remove the mole or lesion, and a small amount — up to 2cm — of surrounding tissue. This helps to ensure they remove any remaining cancerous cells. Upon completion, they may send the specimen for lab analysis.
Curettage and electrodesiccation — this technique involves scraping the lesion and then administering a high-frequency electrical current to the surrounding tissue, effectively zapping any remaining cancer cells.
Cryosurgery — this technique allows your provider to apply liquid nitrogen to freeze and destroy the cancer.
Mohs surgery — in this case, clinicians trained for this technique will remove the lesion in very thin layers until they arrive at cancer-free tissue.
External beam radiation — this space-age sounding treatment directs a focused beam of radiation at your cancer. This one is done at a hospital or specialized treatment centre.
Photodynamic therapy — this technique uses a light-activated drug and light exposure to eliminate your cancer.
Topical therapy — in this case, the dermatologist prescribes a cream that contains specific cancer-targeting drugs. Patients apply it to the affected area on a daily basis for a few weeks.
Punch biopsy — under local anesthetic, this technique allows for partial or complete removal of the suspicious lesion. The specimen is then examined under a microscope for abnormal or cancerous cells.

How do you prevent skin cancer?

Exposure to UV radiation is the biggest predictor of whether you’ll develop skin cancer. This makes sun protection the most important way of preventing skin cancer, such as:

Wearing a broad-spectrum sunscreen every day, regardless of the weather. This will protect you from both kinds of ultraviolet rays — UVA and UVB.
Avoiding tanning beds and prolonged sun exposure
Staying out of the sun between 10am to 4pm when it’s most intense
Covering up — wearing a hat and clothing that covers your arms and legs
Wearing sunglasses with UV protection. Your eyes can burn too — it’s called photokeratitis.
Protecting young children from sunburns and other sun damage with protective clothing and sunscreen

Know your skin

All skin cancers, including melanoma, have better outcomes when you find them early. This means that it’s crucial to check your body regularly for any changes to your skin.

If you have a number of moles and live in Toronto, mole mapping can help you do this. Mole mapping provides you with a full, dermatologist-reviewed report of your body’s moles. Not only does it give you peace of mind that any concerning moles will be flagged, it’s also a great way to keep track of any changes in the size, shape, or colour of your moles over time.

If, however, you have a mole you’re concerned about and feel like it can’t wait, an online dermatology consultation can help. Dermatologists are specially trained to recognize suspicious moles and the first signs of skin cancer. If you live in Ontario, Quebec, British Columbia, Alberta, Newfoundland and Labrador, or Nunavut, you can skip the usual 90 day wait to see a dermatologist and have an online consultation within 24 hours.

If you’re more concerned about the signs of aging or the overall health of your skin, seeing an online skincare specialist may be a better course of action. A skincare specialist is a physician that can make individualized skincare recommendations based on your specific medical history and concerns. They can also help you develop a skincare routine for healthy skin, and minimize wrinkles and signs of aging. This service is currently available in Ontario, British Columbia, and Nunavut.