Radiotherapy vs Mohs Surgery for Skin Cancer: What Patients Need to Know

For selected basal cell carcinomas (BCC) and cutaneous squamous cell carcinomas (SCC), both Mohs surgery and radiotherapy may be treatment options. However, they work in very different ways.

The most appropriate choice depends on the type of skin cancer, its location and risk features, previous treatment, general health and the potential effects of treatment on appearance and function.

How Mohs Surgery Treats Skin Cancer

Mohs surgery for skin cancer is a specialised surgical technique used for selected BCCs and SCCs.

The cancer is removed one layer at a time. The tissue is carefully mapped and examined under a microscope, and if cancer cells remain at an edge, further tissue is removed specifically from the affected area. The process continues until the examined margins are clear.

This approach allows the surgeon to remove the cancer while preserving as much unaffected tissue as possible. It can be particularly valuable where tumour margins are difficult to define or where conserving healthy tissue is important for appearance or function.

How Radiotherapy Treats Skin Cancer

Radiotherapy takes a different approach. Instead of surgically removing the tumour, carefully planned radiation is directed at the cancer to damage the cells and prevent them from continuing to grow and divide.

For selected BCCs and SCCs, radiotherapy can be used as the main treatment. It may be particularly relevant when surgery is not suitable, would be challenging or could have an important functional or cosmetic impact. In some circumstances, radiotherapy may also be considered after surgery.

Treatment is usually delivered as an outpatient. The radiotherapy technique, dose, and number of sessions depend on factors including the tumour's size, depth, and location, as well as the individual patient's circumstances.

A personalised skin cancer treatment plan therefore considers much more than whether a tumour can be treated with radiotherapy or surgery. The aim is to identify an appropriate balance between cancer control, function, appearance, treatment burden and individual circumstances.

Which Treatment Is More Effective?

There is no single answer that applies to every skin cancer.

Mohs surgery provides precise margin assessment while conserving healthy tissue and offers very high rates of local control for appropriately selected BCCs and SCCs. Radiotherapy can also provide effective local control for selected non-melanoma skin cancers.

Comparing the two using one cure-rate figure can be misleading because the cancers and patients selected for each treatment can be very different.

The distinction between basal cell carcinoma and squamous cell carcinoma also matters. BCC rarely spreads to other parts of the body, although it can cause significant local damage if left untreated. SCC has a greater potential to spread, particularly when higher-risk features are present.

Treatment, therefore, needs to reflect the characteristics and risks of the individual cancer rather than assuming a single approach is universally more effective.

When Mohs Surgery May Be Preferred

Mohs surgery can be particularly useful when preserving healthy tissue and accurately assessing tumour margins are priorities.

It may be considered when a skin cancer:

• Has poorly defined margins
• Is in a location where conserving healthy tissue is particularly important
• Has higher-risk features
• Has returned following previous treatment
• Would require removal of significant healthy tissue with conventional surgery

The indications are not identical for every type of skin cancer. Tumour type, location, size, previous treatment and other risk features all contribute to deciding whether Mohs is appropriate.

Once the examined margins are clear, the resulting wound may be closed directly, reconstructed using a flap or graft, or allowed to heal naturally depending on its size and location.

When Radiotherapy May Be Considered

Radiotherapy can be particularly valuable when surgery is not the most suitable approach.

This may include situations where an operation or reconstruction would be difficult because of other health considerations, or where surgery could have an important functional or cosmetic impact. Patient preference can also form part of the decision when more than one clinically appropriate option is available.

Radiotherapy is not simply a fallback treatment when surgery cannot be performed. For appropriately selected BCCs and SCCs, it can be a definitive treatment in its own right.

The role of radiotherapy for basal cell carcinoma therefore depends on factors such as tumour location, previous treatment, general health and individual preferences.

What About Scarring and Cosmetic Results?

Appearance can be an important consideration, particularly when skin cancer develops on the face.

Mohs surgery is designed to conserve healthy tissue, but it still creates a surgical wound. Depending on its size and location, this may be closed directly, reconstructed using a flap or graft, or allowed to heal naturally. A scar should therefore be expected, although its eventual appearance varies.

Radiotherapy avoids a surgical incision, but that does not mean the skin necessarily remains unchanged.

During treatment, the area may become red, sore or irritated and can peel or crust as treatment progresses. Longer-term changes can include alterations in skin colour or texture and visible small blood vessels.

Cosmetic outcomes therefore need to be considered over the longer term rather than reducing the comparison to "scar versus no scar".

Recovery Is Different With Each Treatment

Mohs surgery is usually completed in one day, although patients may spend several hours at the clinic while successive tissue samples are processed and examined. Recovery then depends largely on the size of the wound and whether reconstruction was required.

Radiotherapy does not create a surgical wound, but treatment is usually delivered over a planned course of outpatient sessions. The exact schedule varies according to the cancer and radiotherapy regimen. Skin reactions may develop gradually during treatment and can continue for a period after the final session.

For some patients, completing treatment surgically in one day is preferable. Others may place greater value on avoiding an operation, particularly when reconstruction would be substantial.

Neither experience is universally easier. They are simply different.

Age and General Health Can Influence the Decision

Age alone should not determine whether someone receives Mohs surgery or radiotherapy - unless you are very young.

The main risk of radiotherapy is secondary cancer induction, and that risk slowly rises over the decades that follow radiotherapy. So if you're older, this probably won't be an issue in your lifetime, but if you're younger, it may be.

However, it forms part of a broader assessment. General health, ability to undergo surgery, medications, tumour location and the potential for long-term treatment effects can all influence the recommendation.

Radiotherapy may be particularly useful for some older patients or people for whom surgery presents additional challenges. Conversely, potential late effects from radiotherapy may be more relevant when considering treatment in younger patients.

This is why treatment decisions should be individual rather than based on a simple age cut-off.

When Another Specialist Opinion Can Help

Sometimes there is a clear reason to recommend Mohs surgery or radiotherapy. In other cases, more than one approach may be reasonable, and the differences become more finely balanced.

This can be particularly relevant for recurrent cancers, lesions in complex facial locations or situations where the potential cosmetic and functional consequences of treatment are important.

Discussing an established diagnosis with a private oncology consultant can provide greater clarity around how radiotherapy fits alongside surgical and other treatment options.

If you remain uncertain about a recommendation you have already received, a second opinion can provide an independent review of the existing diagnosis, results and proposed treatment.

Radiotherapy or Mohs Surgery: How Is the Choice Made?

For selected non-melanoma skin cancers, the question is not whether radiotherapy or Mohs surgery is universally "better".

Mohs provides surgical removal with detailed microscopic assessment of the margins while conserving healthy tissue. Radiotherapy avoids an operation and can provide effective treatment for appropriately selected patients, including some situations where surgery would be difficult or undesirable.

Other skin cancer treatment options may also be appropriate depending on the diagnosis. Standard excision, topical treatments and other local approaches have roles in selected skin cancers, so the decision is not always limited to Mohs surgery and radiotherapy.

The recommendation should ultimately reflect the characteristics of the cancer, the likely advantages and disadvantages of each treatment and the patient's individual circumstances and priorities.

About Dr James Wilson

Choosing between radiotherapy and Mohs surgery involves more than comparing treatment success. Tumour type and location, surgical consequences, potential long-term skin effects, general health and individual priorities can all contribute to deciding which approach is most appropriate.

Dr James Wilson is a consultant clinical oncologist in full-time private practice in London, specialising in melanoma, skin cancer and advanced radiotherapy. He helps patients with established skin cancer diagnoses understand their treatment options and make informed decisions about their oncology care.