Superficial Radiotherapy

What is superficial radiotherapy?

Superficial radiotherapy uses low-energy X-rays or electron beams, aimed from a machine outside your body, to treat cancer that's on or very close to the surface of your skin. Because the radiation only travels a short distance into your skin, it avoids the deeper tissues and organs underneath.

What conditions does it treat?

Superficial radiotherapy is mainly used for non-melanoma skin cancers and can also treat some non-cancerous skin conditions. It may be used to treat:

• basal cell carcinoma, a common and usually slow-growing type of skin cancer
• squamous cell carcinoma, including squamous cell carcinoma in situ
• skin cancer on areas that are harder to remove surgically, such as the nose, eyelids or ears
• skin cancer in people who are not able, or do not want, to have surgery
• remaining cancer cells left behind after surgery, to lower the chance of the cancer coming back
• some non-cancerous skin conditions, when your doctor recommends it.

What are the benefits of having superficial radiotherapy?

Superficial radiotherapy is non-invasive: there's no cutting, and it doesn't need an anaesthetic. Because the radiation doesn't travel far into your body, side effects are largely limited to the treated area rather than affecting the organs underneath.

It can be a good option for skin cancers on the nose, eyelids or ears, where surgery could be more complex or change how the area looks and works. Reported recurrence rates vary between studies, from as low as around 2% in closely-monitored series of carefully selected patients up to around 16% in others, so your doctor will discuss what's realistic for your particular cancer.

Are there different types or approaches?

There are two main ways to deliver superficial radiotherapy: with low-energy X-rays (photons), using a compact, wheeled superficial X-ray machine, or with electrons, delivered using a linear accelerator (LINAC) fitted with an attachment called an applicator. Your doctor chooses between them based on the size, depth and location of your skin cancer.

A related technique called brachytherapy places a radioactive source directly on or into the tumour for a short time, rather than aiming a beam from outside the body. This isn't the same as superficial radiotherapy, but your doctor may mention it as an alternative, particularly for cancers on the head or neck.

What happens before the operation?

Before your treatment starts, you'll have a planning appointment so your team can work out exactly where and how much radiotherapy you need.

• Your doctor examines the area, often using a bright light and magnifying glass, and marks the exact area to be treated with a felt pen
• Your radiographers take precise measurements, and sometimes a tracing or template of the area, so they can position you the same way at every session
• With your permission, a digital photograph of the area may be taken to help with accuracy, seen only by the team treating you
• You may need a CT scan to check how deep the radiation needs to go
• For some areas, a custom lead shield or mould is made to protect the healthy skin around the cancer, which can mean an extra appointment
• Any felt pen marks are removed before you leave, and you'll be given your appointment dates for treatment.

What happens during the procedure?

Each treatment session follows a similar pattern:

1. You lie down on a treatment couch, and your radiographers help position you using the measurements, photographs and any template from your planning appointment.
2. Your radiographers place the treatment machine's applicator on or close to your skin, or tape a custom lead shield in place if you have one.
3. Your radiographers leave the room but watch you the whole time on a camera, and you can raise your arm if you need them.
4. The machine delivers the radiation, making a beeping sound; you won't feel anything, but it's important to lie very still and breathe normally.
5. Once treatment finishes, your radiographers come back in, remove any shield, and you're free to go home.

Treatment sessions are usually short, often around 5–10 minutes, though the exact time depends on the dose your doctor has prescribed. Your doctor will tell you how many days of treatment you need, which can range from a single session or many sessions, given daily on weekdays or on alternate days.

What does recovery look like?

Superficial radiotherapy is given as an outpatient treatment, so you go home after each session and don't need to stay in hospital. You're not radioactive at any point, so it's completely safe to be around other people, including children and pregnant people, straight away.

Skin changes in the treated area are the most common effect. Your skin will gradually redden or darken, and may become dry, itchy or scabbed; this usually starts around 10 days to 2 weeks into treatment, peaks about a week after your last session, and settles over the following 4–6 weeks. Try not to pick at any scabs, since letting them heal naturally reduces the risk of scarring.

Hair in the treated area will fall out, usually starting towards the end of treatment, and often regrows after around 3 months, though occasionally hair loss is permanent. Tiredness is also common, both during and after treatment, and can take several months to fully settle.

Keep the area clean with warm water and your usual soap, pat it dry rather than rubbing, and use a fragrance-free moisturiser (at least 4 hours before a session). Protect the area from the sun with a high-factor sunscreen (SPF 50+), since treated skin stays more sun-sensitive long term.

What are the risks and complications?

Because the radiation only reaches the surface, side effects are generally limited to the treated area, but can include:

• redness, soreness, scabbing or, rarely, minor bleeding in the treated skin
• hair loss in the treated area, which is sometimes permanent
• more significant skin breakdown (ulceration), which is more likely on the trunk or legs than on the head or neck, and can take several weeks to heal
• paler skin, or small visible blood vessels, appearing months to years after treatment
• a very small chance, under 1%, of a new skin cancer developing in the treated area years later
• if treatment is near the eye, a small chance of cataracts developing over the following years, and treatment can't usually be repeated in an area that's already had radiotherapy.