Radiation Therapy

High-energy radiation can be used to kill cancer cells.1 External-beam radiation therapy is one way to treat skin cancer. A machine outside the body delivers a beam of electrons to the tumor.1,2 The radiation damages DNA in the cells. The damage causes them to stop dividing or die.1 Another term for radiation therapy is radiotherapy.

Radiation therapy can be used as a main treatment for skin cancer. It is also used as a secondary treatment (adjuvant) for higher risk cancers and for palliative therapy. The goal of palliative therapy is symptom relief, not curing the cancer.

How is external-beam radiation therapy given?

External-beam radiation therapy with charged electrons is the most common type of radiation therapy for skin cancer. The doctor who performs radiation therapy is called a radiation oncologist. Radiation damages normal cells as well as cancer cells. For this reason, the radiation dose and angles are planned carefully with the goal of minimize damage to healthy cells.1 Planning starts with imaging tests to get a picture of the tumors inside the body. Body molds or head masks may be made for you. They are used so that you can be comfortable and still for each treatment. Your skin may be marked temporarily or permanently. Your radiation technician uses these marks for precise positioning.1 You will receive instructions about caring for the marks.

The actual radiation treatment is painless and takes about 15 minutes. Radiation therapy is an outpatient procedure. You will change into a hospital gown. The radiation therapist and a physician will check your position before the treatment. This step is important. Treatment must be delivered to the correct location. The radiation therapist will not be in the room during your treatment. She or he will be able to see you via cameras. You will be able to talk via intercom.

You will need several daily treatments over the course of weeks.1 You will meet with your doctor regularly. You can discuss any side effects you experience. You should ask how the treatment is working.

Is internal radiation therapy used to treat skin cancer?

Internal radiation therapy is when a radioactive material is placed on or in the body.1 This type of radiation therapy is the main treatment for melanoma of the eye. A radioactive plaque is placed near the tumor. The word for this is brachytherapy. The plaque stays in place for several days. Then your doctor removes it.3

When is radiation therapy used as a primary (main) treatment for skin cancer?

Surgery is the preferred treatment for most cases of skin cancer. However, the tumor size or location may make surgery impossible. Surgery may not be an option because of co-existing medical conditions. If surgery is not possible, radiation therapy can be an alternative.2,4,5 When radiation therapy is used to treat skin cancer, it is typically reserved for patients older than 60 years. The reason is that future skin cancers may develop at the radiation site.

Radiation therapy can be a primary (main) treatment for:2,5-7

  • Large non-melanoma
  • Non-melanoma skin cancer in complicated or delicate locations
  • Lentigo maligna melanoma
  • Kaposi sarcoma lesions on the skin, mouth, or throat
  • Merkel cell carcinoma that has returned (recurred) or is likely to recur

The 5-year recurrence rates after radiation therapy for non-melanoma skin cancer are:8,9

  • Basal cell carcinoma (BCC): 4% and 16%
  • Squamous cell carcinoma (SCC): 4% to 10%

When is radiation therapy used as adjuvant treatment?

Adjuvant therapy is an additional cancer treatment that is given after the primary (main) treatment. Adjuvant therapy lowers the risk that the cancer comes back. Primary treatment for skin cancer is often surgery, with radiation therapy as an adjuvant therapy. Radiation kills cancer cells left after the skin cancer was removed.2 This is recommended for:

  • BCC, SCC, or melanoma that grew into a nerve.6,8,9
  • Non-melanoma skin cancer when cancer cells are found on the edges of the sample (positive margins) despite Mohs surgery.
  • Deep desmoplastic melanoma, a type of melanoma that is likely to recur.6
  • Melanoma that recurs.6

Adjuvant radiation therapy is also recommend after lymph node removal.4,6 Without radiation therapy, 40% of high-risk individuals have recurrent melanoma in the remaining lymph nodes.10 With adjuvant radiation therapy, about 10% of people have lymph node cancer recurrence.10

When is radiation therapy used as palliative therapy?

Palliative therapy improves quality of life for people with life-threatening disease. The goal of palliative therapy is to relieve symptoms. The goal is not to treat or cure the disease. Palliative radiation therapy is used to shrink melanoma tumors in the brain or the bone.4

Who is not a candidate for radiation therapy?

Some genetic conditions increase the risk of skin cancer. Examples include basal cell nevus syndrome or xeroderma pigmentosum. Radiation therapy is not used to treat people with these conditions.

Radiation therapy can cause long-term side effects. One of the long-term risks is future skin cancer in the treatment area. For this reason, doctors may be reluctant to treat people younger than 60 with radiation.8

What are the risks of radiation therapy?

The electrons used for external-beam radiation therapy for skin cancer do not go deeper than the skin.1,2 This limits the side effects of radiation therapy.2 Nevertheless, there are many possible side effects of radiation. They include:2,4,6

  • Skin irritation or sunburn-like reaction
  • Changes in skin color
  • Hair loss in the treated area
  • Damage to salivary glands and teeth when the head or neck are treated
  • Fatigue
  • Nausea
  • Pain
  • Nerve damage
  • Joint problems

Brain radiation therapy can cause problems such as memory loss, headaches, trouble thinking, and reduced sexual desire.4

What questions should I ask before radiation therapy?

Questions to ask your doctor about radiation therapy include:11

  • What is the goal of radiation therapy for me?
  • What are the other options for treating my cancer?
  • How will the radiation be delivered? How often and for how long will I need treatments?
  • What short-term side effects should I expect?
  • What are the long-term side effects of radiation treatment?
  • How likely is it that the cancer returns or spreads without radiation therapy? How likely is recurrence or metastasis with radiation therapy?
  • How often should I have follow-up exams with my dermatologist to check for cancer recurrence or a second skin cancer?
Written by: Sarah O'Brien | Last reviewed: May 2017.
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