While receiving radiation therapy for breast cancer, some people have a wet towel covering the breast. Doctors will often apply a bolus — which can be a wet towel or other type of material — during radiation therapy after a mastectomy. Many members of MyBCTeam have talked about using a wet towel during their treatment and recovery. You may be wondering why it’s done and how it affects breast cancer treatment and recovery.

One member wrote, “I started radiation this week, and they told me every other day they will put a wet towel over my breast to increase the effect of radiation. They say they do this with almost all women with mastectomies. Has anyone else had this done?”

Someone else said, “Every other day, they would wet a towel and put it on my breast before radiation. It was called a bolus. I still don’t know why they did it.”

“I have had rads. Twenty-five rounds for ‘prevention.’ Thirteen were with a bolus, a wet towel. There were 12 without. The process was five days a week, Monday through Friday,” another member shared.

Why Is a Bolus Used?

After a mastectomy, a bolus is used to give a higher radiation dosage to the surface of the body. Postmastectomy radiation therapy is often recommended for more advanced cases of breast cancer or if other cancer risks are determined in a particular case of breast cancer.

Some people with breast cancer have a high chance of local recurrence, which means the cancer cells can come back to the same area after treatment. This type of recurrence happens mainly in the skin. Radiation therapy is designed to deliver a higher dose of radiation to deeper layers of tissue while sparing the skin. A bolus acts as a tissue layer that receives a lower dose of radiation while increasing the dose of radiation to the skin under the bolus.

A bolus in radiation therapy can also help with irregularities in skin, such as uneven skin caused by surgery scars from a mastectomy, and ensure that radiation reaches all the areas in the skin that require treatment.

“When they radiated my left chest expander, they radiated 3 inches above and 3 inches below to make sure they got any residual cancer cells. They also used a bolus every other day. They placed a wet towel over my entire breast and then radiated it. I sure hope that was enough not to have a recurrence,” a MyBCTeam member said.

Different Types of Boluses

A bolus can be made from various materials including:

• Natural rubber
• Silicone rubber with bismuth (a type of metal) or aluminum
• Paraffin wax
• A putty-like material such as plasticine or Play-Doh
• Superflab, a standard bolus material made from a synthetic gel

A wet towel or wet gauze is sometimes used as a lower-cost alternative to other types of boluses. The thickness of boluses can vary based on how much radiation is needed.

In the field of radiation oncology research, scientists are looking into using 3D printing to create customized boluses based on individuals’ imaging scans. These personalized boluses aim to make radiation treatment more precise and effective.

Side Effects of a Bolus

A bolus is designed to increase radiation dosage to the skin, so using one can increase your risk for skin reactions — also known as skin toxicity or radiodermatitis. Side effects from radiation with a bolus may include:

• Skin discoloration
• Swelling
• Blisters
• Dermatitis (irritation)
• The appearance and feeling of sunburn

MyBCTeam members have expressed concern about skin reactions with a bolus. “Just finished the first week (five sessions) of radiation. So far so good, but I know the side effects come later,” one member shared. “They used a bolus, which worries me a little since it increases toxicity in the skin. I’ll discuss it with my radiation oncologist on Monday.”

Although side effects may go away shortly after treatment ends, they can sometimes last several months. “I did 28 treatments,” another member wrote. “They radiated my entire breast and lymph nodes. The worst part was when they did the bolus treatments using a wet towel over my entire breast area and radiated through the towel. I still have burning six months later.”

Another member said, “I got the bolus, too. So it has now been one week and two days since the last rads. My skin is like night and day! There is still pain inside and out, and the burn isn’t fully healed, but I can function without painkillers! Or I guess I should just say I can function!”

To reduce skin reactions, a bolus is often used in alternating radiation treatments, every other session. A team member described their experience: “Rads are difficult, I had 25 rounds — 13 with a bolus and 12 without. My skin turned black with green hues,” they said. “Burn is still healing. It’s itchy and red. All the blackness is gone and has moved into a red, bumpy phase. And yes, the surgeon was correct. It’s getting better.”

If your doctor recommends radiation treatment with a bolus, it’s important to discuss potential side effects so that you know what to expect. Some side effects of radiation may not be caused by a bolus, so be sure to talk to your oncologist about your recovery after radiation therapy and follow-up exams. If uncomfortable side effects continue, reach out to your doctor for advice.

Skin Care for Radiation Therapy With a Bolus

If you experience skin changes or reactions from radiation treatment with a bolus, there are steps you can take to manage side effects. Here are some skin care tips to help protect your skin during radiation therapy.

• Keep skin moisturized and apply moisturizer before radiation treatments.
• Wear loose, soft clothing.
• Avoid rubbing or scratching treated areas.
• Avoid direct sun exposure and use sunscreen with an SPF of 30 or higher.
• Clean affected areas with warm water and mild soap, don’t rub skin when washing, and gently pat skin dry with a soft towel.
• Avoid hot water such as from hot showers, hot water bottles, or hot tubs.
• Avoid heating pads or ice packs on treatment areas.

Some lotions, creams, ointments, deodorants, and perfumes may irritate affected skin, and some skin products can leave a residue on the skin that may make radiation therapy less effective. Your cancer care team can provide medical advice on topical skin products that are appropriate during and after radiation treatment.

Find Your Team

MyBCTeam is the social network for people with breast cancer and their loved ones. On MyBCTeam, more than 64,000 members come together to ask questions, give advice, and share their stories with others who understand life with breast cancer.

Have you had radiation therapy with a wet towel? Share your experience in the comments below, or start a conversation by posting on your Activities page.