Is Mohs Surgery Effective for Treating Melanoma?

Mohs surgery offers precise removal of early-stage melanomas, preserving healthy tissue, but its use is limited to specific cases and should be discussed with a qualified professional.

Melanoma is the most serious form of skin cancer. When caught early, it is highly treatable. However, melanoma can spread quickly into deeper layers of skin and other parts of the body if not removed entirely. This makes choosing the right surgical technique critically important.

Mohs surgery has become the gold standard treatment for common non-melanoma skin cancers like basal cell carcinoma. But should Mohs also be used to treat melanoma? Here we explore the pros, cons, effectiveness, and risks of using Mohs surgery to remove melanoma.

What is Mohs Surgery and How Does It Work?

Mohs surgery, also called Mohs micrographic surgery, is an advanced technique developed in the 1930s by Dr. Frederic Mohs. It removes skin cancer layer by layer, with each freshly excised tissue layer being immediately examined under a microscope.

This allows the detection of even microscopic roots and extensions of the tumor that are otherwise difficult to see. By tracing out the entire tumor, Mohs surgery can precisely remove all cancerous cells while maximally preserving healthy tissue.

The basic steps in Mohs surgery are:

• The visible tumor is first removed along with a thin layer of surrounding clear margin.
• This tissue layer is mapped, color-coded, and processed into microscope slides.
• The slides are analyzed to see if any cancer cells remain at the edges.
• If cancer cells are still present, the surgeon removes another thin targeted layer of tissue only from the involved region.
• Steps 2-4 are repeated as many times as needed until no cancer cells remain.
• Once clear margins are achieved, the wound is closed up.

This methodical process allows Mohs surgery to remove cancers with up to 99% cure rates while minimizing damage to healthy skin.

Why is Mohs Surgery Considered for Melanoma?

While Mohs surgery is the treatment of choice for basal cell and squamous cell carcinomas, its use in melanoma is more limited. Some key reasons Mohs may be utilized in melanoma include:

• Effectiveness in treating melanoma in situ confined to outer skin layers.
• Ability to trace out tumor borders more accurately than wide excision.
• Maximal preservation of cosmetically and functionally sensitive facial skin.
• Potentially lower recurrence rates compared to standard surgery.

However, criteria for considering Mohs for melanoma are strict, including early stage, superficial disease, and certain high-risk locations on the head and neck area.

Overall success rates are comparable or somewhat improved with Mohs compared to wide local excision or radiation therapy. But melanoma surgeons may still prefer conventional surgery as the first-line option.

In Which Cases Is Mohs Surgery Not Recommended for Melanoma?

Mohs has significant limitations when used for melanoma, which restricts its application in many scenarios:

• Deeply invasive melanomas extending into fat, muscle, or bone.
• Melanomas with aggressive histology and high-risk of metastasizing.
• Poorly defined melanoma borders or satellite lesions.
• Need for wide excision and lymph node staging.
• Lack of specialized pathology staining and skills.
• Inability to reconstruct complex surgical defects.

Additionally, the time taken for precise mapping and analysis of multiple layers may allow any stray melanoma cells more opportunity to spread.

Alternative treatments like radiation or immunotherapy medications may be preferred options over Mohs in higher stage melanomas.

What are the Benefits of Using Mohs Surgery for Melanoma?

When used judiciously in early-stage disease, Mohs surgery for melanoma offers several advantages:

• Extreme precision in tracing out tumor extensions down to a microscopic level.
• Avoiding excess removal of healthy tissue as in wide local excision procedures.
• Lowest recurrence rates of any technique, with up to 99% cure.
• Ideal for delicate areas of the face, ears, scalp, hands, and genitals.
• Shorter surgery and recovery time compared to reconstructive surgery.
• Outpatient basis with only local anesthesia in most cases.

These benefits make Mohs an appealing choice for superficial and limited melanomas in cosmetically vital areas.

What are the Risks and Side Effects of Mohs Surgery for Melanoma?

While serious risks are low in experienced hands, Mohs surgery can result in complications like:

• Residual cancer left behind leading to recurrence and metastasis.
• Incomplete lymph node removal preventing accurate staging.
• Bleeding, poor wound healing, infections at the surgery site.
• Temporary or permanent numbness and nerve damage.
• Unplanned reconstruction or extensive scarring if too much tissue removed.

Post-surgical pain, bruising, and swelling are common temporary side effects. Long term, the site may remain sensitive or discolored.

How Does Mohs Surgery Compare to Other Treatments for Melanoma?

Mohs has pros and cons relative to wide local excision surgery and radiation therapy:

Vs. Wide Local Excision (WLE)

• Tissue Preservation: Mohs surgery excels at sparing healthy tissue due to its meticulous, layer-by-layer approach. WLE removes a larger margin of tissue as a precaution, often leading to larger wounds requiring more extensive repair.
• Cure Rates: For eligible, early-stage melanomas, Mohs may have slightly higher cure rates than WLE. However, more research is needed to confirm this definitively.
• Lymph Node Staging: WLE typically allows for more complete lymph node staging, which helps determine if the melanoma has spread. Mohs can be combined with sentinel lymph node biopsy to assess lymph node involvement.
• Wound Size and Healing: WLE often results in larger wounds that may require skin grafts or flaps for closure, leading to longer healing times and potentially more noticeable scarring.

Vs. Radiation Therapy

• Targeted Treatment: Mohs is highly precise and avoids unnecessary radiation exposure to healthy tissue, reducing the risk of long-term complications.
• Depth of Treatment: Radiation therapy can be used to treat melanomas that have spread deeper into the skin or surrounding tissues, where Mohs is not effective.
• Convenience: Mohs is typically completed in a single session, while radiation therapy usually involves multiple treatment visits over several weeks.
• Long-Term Risks: Radiation therapy carries the risk of long-term skin damage, such as fibrosis, pigmentation changes, and even the development of secondary cancers in rare cases.

Important Considerations

• Melanoma Type and Stage: Mohs is most suitable for early-stage, thin melanomas, particularly lentigo maligna. For deeper or more aggressive melanomas, WLE or radiation therapy may be more appropriate.
• Location: Mohs is often preferred for cosmetically sensitive areas like the face, where tissue preservation is important.
• Expertise: Mohs surgery requires specialized training and expertise, so finding a qualified Mohs surgeon is crucial.

Mohs offers the most precision, but is limited to thin, superficial melanomas compared to the other modalities.

What Should Patients Expect During and After Mohs Surgery for Melanoma?

For those undergoing Mohs surgery for melanoma, steps patients should expect include:

• Preparation for 1-2 days before like avoiding blood thinners.
• Arriving with a driver, as you cannot drive for 24 hours after anesthesia.
• Photography and marking the surgery site for the medical record.
• Receiving a local anesthetic to numb the area.
• The surgeon removing thin layers of tissue, with 1-2 hours between each stage.
• Pressing a bandage to the site after the surgery is complete.
• Instructions for care of the wound and what activities to avoid.
• Some pain, swelling, drainage, and bruising along with numbness lasting weeks.
• Possible antibiotics and pain medication, as well as follow up visits to track healing.
• Minimizing sun exposure and using sunscreen diligently on the site.

Full recovery can take several weeks to months depending on the size and depth of the melanoma removal.

Are There Special Considerations for Specific Types of Melanoma in Mohs Surgery?

The effectiveness and risks of Mohs surgery differ based on melanoma subtype:

Lentigo Maligna Melanoma

• Mohs results in high cure rates for this “in situ” type confined to outer skin layers.
• Preserves more facial skin compared to wide excision procedures.

Desmoplastic Melanoma

• Local recurrence is more common than other melanomas.
• May require multiple rounds of Mohs and margins well beyond visible tumor.
• Higher likelihood of requiring follow-up radiation therapy.

Features like depth of invasion, location, size, and borders dictate whether Mohs or conventional surgery is more appropriate for each melanoma case.

Final Thoughts

Mohs surgery offers a highly effective option for eliminating early-stage, thin melanomas in delicate areas where tissue preservation is vital. However, wide local excision with lymph node staging remains the standard go-to approach for most melanomas.

Careful patient selection and specialist pathologic techniques are mandatory for the limited role Mohs surgery can potentially play in the armamentarium against melanoma. But for more extensive melanomas, conventional therapies continue to be the treatment of choice.