When radiation is used for basal cell, squamous cell, Merkel cell, and melanoma skin cancers, the types and schedules, side effects, and the debate over its routine use.
Surgery cures most skin cancers, so radiation takes a supporting part. It steps in when an operation would be too hard on the patient, when surgery alone leaves too high a risk of the cancer returning, and when the goal is relief of symptoms. How often doctors use it depends heavily on the type of skin cancer.
For these 2 common cancers, radiation can be the primary treatment in people who cannot have surgery or choose not to. Typical examples are a frail person in their 90s, or a large tumor on the eyelid, nose, or ear where surgery would mean a major reconstruction. DermNet, the New Zealand dermatology resource, puts the 5-year cure rate for small, uncomplicated tumors at approximately 90%.
Radiation is also given after surgery, which doctors call adjuvant treatment, when the pathology report shows high-risk features. The main ones are cancer growing along nerves, margins that could not be cleared, and spread to lymph nodes. A short course can also shrink a painful or bleeding tumor that cannot be cured.
Some people should avoid it. The American Cancer Society advises against radiation in young people, because new skin cancers can arise in the treated area many years later. The same applies to people with inherited conditions such as basal cell nevus syndrome or xeroderma pigmentosum, and to people with connective tissue diseases such as lupus or scleroderma, whose skin can react severely.
Merkel cell carcinoma is unusually sensitive to radiation, and radiation is a routine part of its care. Doctors commonly treat the site of the tumor after surgery to kill cells left behind. They may also treat the nearby lymph nodes, either when cancer is found there or when the node status is uncertain.
Melanoma responds less readily, so radiation is used selectively. The American Cancer Society lists 4 situations. Radiation may follow a lymph node dissection when many nodes held cancer, or follow surgery for desmoplastic melanoma, a subtype that tends to recur locally. It can treat some early melanomas when surgery is impossible. It also eases symptoms from spread to the brain or bones.
Skin cancers sit at the surface, so the beam needs little penetration. Several technologies deliver that:
Treatment starts with a planning visit, called simulation, where the team measures and marks the area. Each treatment takes only minutes and is painless, like having an X-ray.
The dose is split into many small sessions called fractions, because normal tissue tolerates small daily doses far better than large ones. DermNet describes 10 to 25 fractions for most skin cancers, given Monday through Friday over 2 to 5 weeks. Shorter courses with larger doses per visit, called hypofractionation, suit people who find daily travel hard.
The early reaction builds over the first 2 to 3 weeks and resembles a sunburn in the treated patch: redness, warmth, then peeling, and sometimes a moist, raw surface with crusting. It peaks near the end of the course and heals over several weeks. Hair in the beam falls out.
Late changes appear months to years afterward and tend to be permanent. The skin becomes thin and pale or, in some people, darker. Small spidery blood vessels called telangiectases show through. A surgical scar improves with time, while a radiated patch often looks its best in the first year and slowly worsens over decades.
Rarely, a new skin cancer forms in the field many years later. The same area generally cannot be radiated twice, so a cancer that returns after radiation needs surgery.
Over the past decade, superficial radiation and electronic brachytherapy have been marketed in the United States for ordinary basal cell and squamous cell carcinomas, including in patients who could easily have surgery. Specialists disagree about this trend, and both sides have reasonable points.
Supporters note that radiation involves no cutting, no anesthesia, and no wound to look after. They report low recurrence rates in published series, several of them around 5% or less over the first years. They argue it serves people with tumors on the lower legs, where surgical wounds heal slowly.
Critics point to what radiation cannot do. No tissue is examined, so no one confirms under a microscope that the whole tumor was treated. Most of the supportive studies are retrospective, with short follow-up, while skin cancers can recur 5 or more years later. A course also means many visits compared with a single procedure.
The American Academy of Dermatology's position statement says that surgical management remains the most effective treatment for basal cell and squamous cell carcinoma, with the highest cure rates. It supports electronic surface brachytherapy as a secondary option for special circumstances, such as when surgery is contraindicated or refused, and calls for more research on long-term outcomes.
If radiation is offered for a routine skin cancer, ask for the expected 5-year cure rate compared with excision or Mohs surgery for your tumor's type and location. Ask how many visits the course takes and how the treated skin is likely to look in 10 years.
