How good is sunscreen in the prevention of skin cancer?

Nodular malignant melanoma in a 92 year-old male. (Dr. Noorali Bharwani)
Nodular malignant melanoma in a 92 year-old male. (Dr. Noorali Bharwani)

In Canada, more than 80,000 cases of skin cancer are diagnosed every year.

We are officially into spring now and summer is round the corner. The sun is shining most of the days and people are walking and running sometimes without adequate clothing. Hopefully, they have sunscreen generously layered over their body. As we know, sunscreen is recommended for prevention of skin cancer but questions about its harms have been raised.

This subject is covered in a review article (The efficacy and safety of sunscreen use for the prevention of skin cancer) published in the Canadian Medical Association Journal (CMAJ Dec 14, 2020). The review is quite detailed. I will try and summarise it.

Because exposure to ultraviolet radiation is estimated to be associated with 80 to 90 per cent of skin cancers, the use of sunscreen — which blocks ultraviolet radiation — is promoted as an important means of preventing skin cancers, as well as sunburn and skin aging.

There are five key points to remember about the use of sunscreen:

  1. Sunscreen use reduces the risk of basal cell, squamous cell and melanoma skin cancers.
  2. Commercial sunscreens protect against the skin-damaging effects of ultraviolet radiation through either chemical or physical ingredients.
  3. The Canadian Dermatology Association recommends the use of an adequate dose of a broad-spectrum sunscreen with a sun protection factor of at least 30 for most children and adults.
  4. Emerging evidence suggests that some chemical sunscreen ingredients are systemically absorbed, but the clinical importance of this remains unclear; further research is required to establish whether this results in harm.
  5. Ultraviolet filters found within chemical sunscreens may be harmful to the environment.

Both the Canadian Dermatology Association and the American Academy of Dermatology recommend the use of sunscreen for the prevention of skin cancer. Then why worry?

What we know:

Since the development of the first commercial sunscreen in 1928, three questions have been raised: are they safe, are they effective, and more recently, the impact of sunscreens on the environment.

The CMAJ article summarizes evidence related to the effectiveness and harms of sunscreen to help physicians counsel their patients.

Sunscreens contain chemical compounds that act to block ultraviolet radiation. There is no doubt the highest-quality evidence available suggests that sunscreens do prevent skin cancer.

People of all skin colours and older than six months should use sunscreen with SPF (Sun Protection Factor) of 30 or higher. The mainstays of sun safety in infants include sun avoidance and protective clothing.

Apply sunscreen generously. Most people tend to underapply. If you are going in water or your activity involves lot of sweating then wait 15 – 30 minutes after applying the sunscreen. And use water-resistance sunscreen.

Recent experimental studies have shown that sunscreen remains on the skin at the desired SPF for as long as eight hours after a single application.

What are the concerns about using sunscreen?

Some recent studies have reported that chemical sunscreen ingredients are detectable in various water sources and may persist despite waste-water treatment processing. An additional recent concern is the detection of sunscreen filters in the tissues of various fish species, raising the possibility of bioaccumulation and biomagnification.

Low-quality evidence has shown that some chemical sunscreen ingredients are systemically absorbed and may be contributing to environmental damage; people who are concerned may consider using physical sunscreens as an alternative. Research on the safety and efficacy of established sunscreens and novel agents is ongoing.


Currently, there are no good scientific reasons not to use sunscreen. Also remember, besides the use of sunscreen, one should follow other rules about sun protection for avoiding ultraviolet radiation, including the use of wide-brimmed hats, eye protection (e.g., “wrap-around” sunglasses with ultraviolet radiation protection) and seeking shade when the ultraviolet index is above 3 (usually 11 am to 3 pm, April to September).

Take care, be safe, use sun protection and get your COVID-19 vaccine to protect yourself, your family and people around you.

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Sun safety and prevention of skin cancer starts in childhood.

Dubai Desert Safari. (Dr. Noorali Bharwani)
Dubai Desert Safari. (Dr. Noorali Bharwani)

Snow has melted and summer is around the corner. It is about time to get some sun exposure and vitamin D. But we have to be careful. We have to find a right balance. Too much sun exposure allows ultraviolet (UV) rays to reach your inner skin layers that gives you sunburn. Sunburn kills your skin cells and cause cancer. You don’t want that.

UV rays are invisible, and are produced by the sun and tanning lamps. Most often, skin cancer is the result of overexposure to sun. Good news is most cases of skin cancer can be prevented.

There are three types of skin cancers. Basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and melanoma. The first two are common and have good prognosis but can disfigure your face. Melanoma can be lethal if not treated early. Melanoma is the least common, but most serious type of skin cancer.

Who gets melanoma?

The rate of melanoma has tripled in the last 50 years. Melanoma is the deadliest skin cancer. It accounts for only about one per cent of all cases of skin cancer, but is responsible for the vast majority of skin cancer deaths.

In men, melanoma is most commonly found on the back and other places on the trunk (from the shoulders to the hips) or the head and neck. The most common sites in women are the arms and the legs. People with fair skin, such as those with Scandinavian ancestry, are more prone to sun damage than people with darker skin.

Approximately two per cent of melanomas occur in patients under the age of 20 years, and about 0.4 per cent of melanomas occur in prepubertal children. Children spend more time outdoors than adults. It is known that high exposure to sunlight during childhood sets the scene for higher rates of melanomas as an adult. Your risk of skin cancer increases with level of total cumulative exposure to the sun and number of sunburns. Melanoma loves overexposed and burnt skin.

What happens after diagnosis?

Your doctor will investigate if the melanoma is at an early stage or advanced stage. Early-stage means the cancer hasn’t grown much and hasn’t spread. Treatment is more likely to be successful.

Advanced-stage melanoma usually means the cancer is bigger and has probably spread. It’s important to know the stage of a cancer. It helps decide on your treatment.

Most early melanomas can be treated with wide surgical excision. But prognosis drops dramatically when the tumor has spread. There is no curative treatment available for advanced melanoma.

While we are waiting for scientific breakthrough in many areas of melanoma, we can try and prevent melanoma by protecting against sun exposure and sun burn. Natural protection (shade) is considered the best protection. And sunscreen (SPF 15 or higher) should be adjunct to natural protection.

Wear sun protective clothing (tightly woven). Wear wide brim hats. And use eyeglasses that block both UVA and UVB light.

Skin is the largest organ in the body. It is a very precious and important organ. It has many important functions. It is important for our survival. Let us protect it well starting from childhood. There is no doubt melanoma risk rises rapidly with increasing exposure to ultraviolet light in childhood. That is where the prevention should start and then continued into adult life.

Have a wonderful safe summer.

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Proper Use of Sunscreen Important to Prevent Skin Cancer

"Trust me, I'm a doctor!" (Dr. Noorali Bharwani)
"Trust me, I'm a doctor!" (Dr. Noorali Bharwani)

Skin cancer is the most common cancer in North America. The benefits of sunscreen outweigh the inconvenience of using it.

First step in the prevention against skin cancer is to avoid sun exposure between 10 a.m. and 2 p.m. whatever the season. These are prime hours for exposure to skin-damaging ultraviolet (UV) radiation from the sun, even on overcast days.

Second step is to wear protective clothing. This includes pants, shirts with long sleeves, sunglasses and a wide-brimmed hat.

Third step is to use sunscreen. Apply sunscreen generously and reapply regularly, says a dermatologist at Mayo Clinic.

There are two types of UV light that can harm your skin – UVA and UVB. A broad-spectrum sunscreen protects you from both.

UVA rays can prematurely age your skin, causing wrinkles. UVB rays can burn your skin. Too much exposure to UVA or UVB rays can cause skin cancer. The best sunscreen offers protection from all UV light.

SPF stands for sun protection factor, a measure of how well sunscreen protects against UVB rays. UVA protection isn’t rated. Manufacturers calculate SPF based on how long it takes to sunburn skin that’s been treated with the sunscreen as compared to skin with no sunscreen.

When applied correctly, a sunscreen with an SPF of 30 will provide slightly more protection from UVB rays than does a sunscreen with an SPF of 15. But the SPF 30 product isn’t twice as protective as the SPF 15 product. Sunscreens with SPFs greater than 50 provide only a small increase in UV protection.

Often sunscreen is not applied thoroughly or thickly enough, and it can be washed off during swimming or sweating. As a result, even the best sunscreen might be less effective than the SPF number suggests.

Rather than looking at a sunscreen’s SPF, choose a broad-spectrum sunscreen. A water-resistant sunscreen means the SPF is maintained for up to 40 minutes while swimming or sweating. Very water resistant means the SPF is maintained for 80 minutes.

Is one sunscreen better than others?

Experts at Consumer Report (May 2017) tested 62 lotions, sprays, sticks, and lip balms. Out of these, 23 tested at less than half their labeled SPF number. That doesn’t mean the products aren’t protective, but you may not be getting the degree of protection you think you are.

To compare the full list of sunscreens you will have to go to the Consumer Report. Here are the top five brands mentioned in the Report:

  1. Equate Sport Lotion SPF 50 (Walmart)
  2. Pure Sun Defense Lotion SPF 50
  3. Equate Ultra Protection Lotion SPF 50 (Walmart)
  4. Trader Joes Spray SPF 50+
  5. Equate Sport Continuous Spray SPF 30 (Walmart)

If you cannot find one of the above sunscreens, then choose a chemical sunscreen with an SPF of 40 or higher that will give you a better chance of getting at least SPF 30.

How to use the sunscreen?

  1. Shake it well.
  2. Apply 15 to 30 minutes before going out.
  3. Use at least a teaspoon on each body part.
  4. Reapply every two hours.
  5. Use spray sunscreens carefully so you don’t inhale it, they can also be flammable. Avoid using sprays on children.

Be safe and enjoy the summer.

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Smart Sunscreen Strategy Needed to Prevent Skin Cancer

Sunset in Hawaii. (Dr. Noorali Bharwani)
Sunset in Hawaii. (Dr. Noorali Bharwani)

There are three types of skin cancers. Basal cell cancer (BCC) and Squamous cell cancer (SCC) are not lethal but can leave you with scars and deformities on your face and other parts of the body. Then there is melanoma. If not detected early and treated melanoma can be lethal.

When exposed to sunrays, some people burn easily and others slowly. Those who burn easily have a higher risk of skin cancer than others. But everybody is at some risk of getting skin cancer. So be smart and prevent skin cancer. Here are some guidelines.

Minimize sun exposure. Avoid the sun or stay in the shade when the sun is the strongest (10 a.m. to 4 p.m.), and dress right for the occasion. Wear a hat and clothing that’s made from tightly woven fabric.

Use appropriate sunscreen. The American Academy of Dermatology (AAD) guidelines recommend people use sunscreens with three important qualities:

  1. Use broad-spectrum sunscreen to protect against ultraviolet A rays and B rays. Ultraviolet A rays make up 95 percent of the UV spectrum and are most associated with wrinkling. Ultraviolet B rays, cause sunburn and are stronger at midday and in the summer. Both types of rays can cause skin cancer.
  2. Use water resistant sunscreen – no sunscreen is “water proof” but water resistant means you can go up to 80 minutes in the water before you need to reapply.
  3. Use sunscreen with SPF of at least 30.

To understand what sunscreens people actually use compared to what they need to prevent burning, the researchers looked at the most popular sunscreens on Amazon – the top one per cent, or 65 products.

The researchers found 40 percent – 26 of 65 – of the products did not meet AAD requirements. Most products that failed to meet the standards, 72 percent, did so because they were not water resistant.

A Consumer Reports study (May 2016) found only the following five met the AAD criteria:

  1. Hawaiian Tropic Sunscreen Silk Hydration SPF 30
  2. Neutrogena Age Shield Face Lotion Sunscreen SPF 110
  3. EltaMD UV Physical SPF 41
  4. Neutrogena Ultra Sheer Dry – Touch Sunscreen SPF 55
  5. Neutrogena Sunscreen Ultra Sheer Stick SPF 7

Make sure you use enough sunscreen. Apply sunscreen 15 to 30 minutes before you go outside. For lotions, a good rule of thumb is a teaspoon per body part or area.

For sprays, apply as much as can be rubbed in, then repeat. Regardless of which kind you use, reapply every two hours and after swimming or sweating. Use spray sunscreens carefully. Sprays are flammable; so let it dry before going near an open flame.

Consumer Reports article concludes by saying, “Tests over the past four years indicate that choosing a chemical sunscreen with an SPF of 40 or higher will give you a better chance of getting at least an SPF 30. Using any sunscreen is better than using none, but it’s just one part of a smart sun protection strategy.”

Take care and enjoy the summer.

Start reading the preview of my book A Doctor's Journey for free on Amazon. Available on Kindle for $2.99!