Prudent and moderate exposure to the sun has clear benefits, but excessive exposure has proven harmful effects.

It has been established that 50-80% of the sun exposure we receive in our lifetime occurs during the first 20 years of life, so education aimed at encouraging good habits when exposing ourselves to the sun is key for this age group.

In this article we will give specific advice on how to provide adequate sun protection for patients receiving treatment for breast cancer and, in addition, we will provide a series of recommendations regarding photoprotection for the general population.

What kind of radiation is the most harmful to our skin?

Ultraviolet (UV) radiation is the part of solar radiation (SR) which is the main risk factor in the development of skin cancer and photoaging.

There are three subtypes of UV radiation: UVA, UVB and UVC; but only UVA and UVB will penetrate the surface of the Earth, with UVA accounting for most of what we receive from SR (>95%).

Mainly UVA and UVB are responsible for the damage that our skin and eyes may suffer. UVB is more aggressive, and is the cause of sunburn and skin cancer as it causes direct damage to DNA.

UVA is less aggressive, but penetrates our skin more deeply and will be primarily responsible for the skin photoaging and pigmentation associated with SR. It may also contribute to the development of skin cancer, but to a lesser extent than UVB.

What are the benefits of sun exposure?

For many people, being exposed to sunlight produces a state of ‘psychological well-being’, as it induces the production of serotonin and endorphins. It also contributes to vitamin D synthesis (important for the health of our bones and muscles) and can also help to prevent certain diseases.

What are the harmful effects of chronic sun exposure?

The main harmful effects derived from prolonged and chronic exposure to the sun are the development of skin cancer and photoaging, the latter consisting of the appearance of a series of skin changes due to chronic sun exposure such as fine and coarse wrinkles; saggy, rough and dry skin; spider veins; and pigmentation changes (sun spots, freckles, melasma, hypopigmentation).

In addition, chronic exposure to the sun, specifically UVB, can lead to many eye conditions such as cataracts and eye cancer.

Recommendations for breast cancer patients:

These are the main photoprotection recommendations for patients with breast cancer, to protect surgical wounds or scars, and for those who are receiving chemotherapy or radiotherapy treatment.

What specific care should be taken to protect the scar after breast cancer surgery?

We must bear in mind that a fresh scar is very vulnerable tissue and it takes months, even several years, to form a mature or permanent scar. For this reason, in addition to applying daily moisturizing cream, special care must be taken not to expose the scar to direct sunlight, due to the risk of it acquiring a darker tone (hyperpigmentation). To achieve this, we can cover it with clothing, apply topical SPF 50 sunscreen and/or use healing sheets or patches, some of which also contain specific sun protection.

If I am receiving chemotherapy for breast cancer, should I be especially careful with the sun?

Many chemotherapy drugs used to treat breast cancer can increase the skin’s sensitivity to ultraviolet radiation (photosensitivity). This can manifest itself in different ways, such as an increased tendency to burn, skin hyperpigmentation, or skin rashes within minutes of exposure to the sun.

Increased pigmentation (hyperpigmentation) is also a common side effect that can be caused by a large number of chemotherapy treatments and can affect the skin as a whole, hair, nails and mucous membranes.

Antiestrogens induce drier skin, more vulnerable to damage (including UV radiation), with the premature appearance of wrinkles due to loss of dermal density.

Given these side effects, it is essential that a patient receiving chemotherapy is adequately protected from the sun by wearing protective clothing and/or topical sunscreens of SPF 50 or higher (especially physical or mineral filters), avoids sun exposure as much as possible between 11:00 and 17:00, and does not use artificial tanning booths.

Should I specifically protect my skin if I am receiving radiation therapy?

The area of skin that has received or is receiving radiation therapy will develop a number of skin changes (radiodermatitis) that will depend on the type and intensity of radiation therapy given. These changes usually consist of the appearance of redness and swelling during the first two weeks, followed by thinning or atrophy of the skin, pigmentation changes and telangiectasia.

For this reason, skin that has received radiotherapy becomes more sensitive to ultraviolet radiation and it is recommended that only short periods of exposure to the sun be made, avoiding the hours of the day when the intensity of solar radiation is at its highest (12:00-16:00), using protective clothing and/or physical filters (mineral) and reapplying topical sunscreen frequently if exposure to the sun is going to be longer.

Recommendations for the general population:

Recommendations for the general population regarding healthy sun exposure habits are as follows:

The first line of sun protection consists of avoiding sun exposure and the use of clothing, wide-brimmed hats and wraparound sunglasses with UV protection. Thicker clothing with tighter-fitting fabric, such as polyester and cotton, or nylon and elastane (e.g. spandex, lycra) and darker colours offer greater protection. There is evidence to support the usefulness of specific sun protection clothing (with SPF labelling) over regular clothing since, although certain regular garments may provide comparable photoprotection, the spectrum of photoprotection offered by regular clothing is more variable.

The use of topical sunscreens would be considered a second line of sun protection. Topical sunscreens contain chemical (organic) or physical (inorganic) compounds that act by blocking UV radiation and are active against UVA and UVB.

Chemical filters are compounds that absorb UV radiation and convert it to lower energy wavelengths; they are more cosmetic than physical filters but can cause allergic reactions at the site of application.

Physical filters, such as titanium dioxide and zinc oxide, reflect or refract UV light away from the skin.  They are less cosmetic than chemical filters but, being inert powders, they do not cause irritation or sensitization.

Correct application of topical sunscreen is key to the effectiveness of these products. A uniform and generous film of sunscreen should be applied (a teaspoon-sized amount for head and face, two for the torso, one for each arm and two for each leg), and it should be applied 20-30 minutes before sun exposure.

Health authorities recommend regular use of sunscreen with an SPF of 30 or higher for people of all skin types, although skin cancers are much more common in people with fair skin than in those with darker skin.

Sunscreen is not recommended for children under six months of age. The pillars of sun safety in babies include avoiding the sun and wearing protective clothing.

Sunscreen (with an SPF equal to or lower than that of the first application) should be reapplied after bathing or excessive sweating. It is not strictly necessary to reapply sunscreen every two hours without having sweated or having done any physical activity. According to recent studies, without exercising or sweating, an SPF 50 filter would maintain the same effectiveness for at least the first six hours after application and, thereafter, the effectiveness would gradually decrease to an SPF 30.

Avoiding sun exposure as much as possible and seeking shade when the UV index is higher than 3 (usually between 11:00 and 16:00) is recommended.

On cloudy days we should still protect ourselves from UV radiation. UV radiation is reduced by approximately 50% with complete cloud cover, whereas partial cover does not adequately protect from UV light, with only 10% usually being blocked by clouds.

Oral photoprotectors contain one or more ingredients that promote skin photoprotection via different mechanisms and can complement (but never replace) topical sunscreens. Some of these ingredients help prevent the development of UV-induced premalignant skin lesions and minimize the risk of sunburn.

In 2009, tanning devices that emit ultraviolet rays, i.e. sunbeds and tanning booths, were officially classified as carcinogenic for human health by the International Agency for Research on Cancer. Some countries have implemented total bans, while others restrict access to children under the age of 18.

The WHO recommends that facilities offering tanning bed services should provide adequate information to consumers and limit their use to those over 18 years of age.

A collaboration for the IBCC of:

Verònica Ruiz Salas, MD PhD. Dermatologist. Derma Associats. Institut Dermatologia Garcés. Centro Médico Teknon (Teknon Medical Centre).

Dr. JR Garcés, Medical Director of the Institut Dermatologia Garcés. Coordinator of the Skin Cancer Unit at the Instituto Oncológico Teknon (Teknon Oncology Institute) in the Centro Médico Teknon (Teknon Medical Centre).

Bibliography:

1. Sanborn RE, Sauer DA. Cutaneous reactions to chemotherapy: commonly seen, less described, little understood. Dermatol Clin, 2008;26:103-19
2. Alley E, Green R, Schuchter L. Cutaneous toxicities of cancer therapy. Curr Opin Oncol, 2002; 14: 212-6.
3. The risks and benefits of sun exposure. David G Hoel, Marianne Berwick, Frank R de Gruijl, Michael F Holick. Dermatoendocrinol 2016 Oct 19;8(1):e1248325
4. Novel Means for Photoprotection. Kevin Sondenheimer, Jean Krutmann. Front Med (Lausanne) 2018 May 29;5:162