Sun Safety During Chemo and Radiation: What You Need to Know
Sun safety is always important. Exposure to ultraviolet A (UVA) and ultraviolet B (UVB) rays from the sun damages skin in ways that can lead to wrinkles, sunburns, and skin cancer. More than 9,500 people are diagnosed with skin cancer every day in the United States.
Protecting your skin from the sun is even more crucial during cancer treatment. "Some cancer therapies make patients very prone to sunburns," says Jonathan Leventhal, MD, the director of onco-dermatology at Smilow Cancer Hospital at Yale School of Medicine in New Haven, Connecticut. Radiation, certain chemotherapy drugs, and other cancer medications like epidermal growth factor receptor (EGFR) inhibitors and BRAF inhibitors make skin highly sensitive to the sun, he says. The sun can also aggravate rashes caused by radiation therapy and targeted therapy.
Both chemotherapy and radiation therapy make the skin more sensitive to UV radiation from the sun. Other types of medicines, including immunotherapy and targeted therapy, can have the same effect. Drug-induced light sensitivity happens when sunlight activates some of the ingredients in cancer drugs.
A phototoxic reaction is the most common risk from chemotherapy and sun exposure. With this type of reaction, UV light exposure changes the chemical makeup of the chemotherapy drug, causing it to release energy that damages the skin. Within hours after getting the chemotherapy drug and being outside in the sun, a person may find that areas of sun-exposed skin (such as the face, chest, arms, and legs) have turned red and swollen as they would with a sunburn.
Photoallergic reactions are like allergies to the sun. They're less common than phototoxic reactions. Within one to three days after a person receives the cancer drug and is exposed to the sun, the skin erupts in an eczema-like rash. Repeated exposure to the drug and sun can make the rash spread.
The chemotherapy medications that are most likely to cause sun sensitivity are:
Dacarbazine
Fluorouracil (5-FU)
Methotrexate
Nab-paclitaxel
Vinblastine
The combination of radiation therapy and sun exposure also causes phototoxic reactions. As little as 10 minutes outdoors after radiation treatment without adequate sun protection can damage the skin. Sun exposure after either chemotherapy or radiation therapy can result in painful skin rashes and sometimes blisters, says Dr. Leventhal.
People who are taking certain cancer drugs or who are on radiation therapy are usually advised to avoid direct sun exposure during treatment, and for a period of time afterward.
Sensitivity to Heat
Heat may be a problem, too. Some cancer treatments, including hormonal therapies, make it harder for the body to regulate temperature, causing increased heat sensitivity. Cancer drugs may also cause sweating, flushing, and dehydration during warm weather. "Keeping hydrated and minimizing sun exposure are essential," says Leventhal. Stay inside in the air conditioning when it's hot outside, and avoid very warm places like steam rooms, saunas, and hot tubs.
It's not necessary to avoid being outdoors altogether, but being careful about sun exposure can prevent burns and rashes during cancer treatment.
Limit Time in the Sun
Plan outdoor activities during times when sunlight is weakest, such as early in the morning or late in the afternoon. The hours of 10 a.m. to 4 p.m. are when most UV exposure and sun damage occur.
Try to avoid direct sunlight by staying in the shade, such as under an overhang, tree, or umbrella. Remember that water, sand, and snow also reflect the sun's rays onto the skin and can cause severe burns.
Apply Sunscreen
Before going outside, apply a generous amount of sunscreen with a sun protection factor (SPF) of 30 or higher, broad-spectrum UVA/UVB protection, and water resistance — even on cloudy days.
"Sunscreen should be applied to all exposed skin, with frequent reapplication, especially after swimming and sweating," says Leventhal. Add an SPF 30 or higher lip balm to shield your lips from sun damage.
Cover Up
Wear ultraviolet protection factor (UPF) clothing, including lightweight long pants and long-sleeved shirts that are tightly woven so they don't let in UV rays. Completely cover any areas of skin that have been exposed to radiation. Protect your head and face with a wide-brimmed hat or scarf and UV wraparound sunglasses.
Stay Hydrated
Cancer treatments like chemotherapy and radiation and their side effects, like vomiting and diarrhea, increase the risk of dehydration. Heat and sun exposure deplete the body of fluid even more. Drink cool water or a sports/electrolyte drink often while outside to stay hydrated.
Spending too much time in the sun can lead to sunburn, sun poisoning, heat exhaustion, and heatstroke. Common symptoms of too much sun exposure include:
Skin that looks pink or red, or that feels warm or hot to the touch
Pale and clammy skin
Swelling under the skin
Fluid-filled blisters
Headache
Fever
Nausea
Tiredness
Weakness
Dizziness
Fast heartbeat or breathing
If you experience any symptoms like these, go inside to cool down and drink fluids. Get medical assistance if symptoms don't improve.
It's not likely. "The sun itself shouldn't impact the effectiveness of cancer treatment," says Leventhal. But sun exposure can worsen the rashes that cancer treatments like chemotherapy, targeted therapy, and radiation therapy sometimes cause. That's why it's best to avoid sun exposure while you’re undergoing treatment.
One benefit to being out in the sun is that the skin produces vitamin D when exposed to UV rays. This vitamin maintains bone and muscle strength, and it helps protect the immune system and the nervous system. The recommended dietary allowance (RDA) of vitamin D for adults ages 51 to 70 is 600 international units (IU), and for adults over 70 it's 800 IU daily.
While undergoing cancer treatment, the safest way to get vitamin D is from a supplement. You can also incorporate vitamin D–rich foods into your diet, such as fatty fish like salmon, trout, and tuna. Wild-caught fish tend to have higher levels of vitamin D than farm-raised. Fortified cow's milk, almond milk, and soy milk are also good dietary sources of vitamin D.
Sun safety is always important, but it’s especially so during cancer treatment. Chemotherapy, radiation therapy, and some other cancer medications make the skin more sensitive to the effects of UV light.
Too much sun exposure can cause skin rashes, blisters, and burns.
Try to stay out of the sun between the hours of 10 a.m. and 4 p.m. Wear sun-protective clothing and sunscreen while outdoors, and drink extra water to prevent dehydration.
