Mohs micrographic surgery: Removing skin cancer with up to a 99% cure rate

Mohs micrographic surgery is a specialised type of frozen section surgery used to treat skin cancer. It’s mainly used to remove basal and squamous carcinomas with up to a 99% cure rate, which is greater than rates from radiotherapy and standard surgery, and is the highest cure rate of any method of treating skin cancer. Our dermatologists offer Mohs surgery to private patients at Wimpole Street Consulting Rooms and Diagnostic Centre. Learn more about the procedure from Dr Rakesh Patalay, consultant dermatologist and dermatology surgeon at Guy’s Hospital and Wimpole Street. 

What causes basal and squamous cell carcinomas? 

Basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) are the 2 most common types of non-melanoma skin cancer. In almost all cases, BCC and SCC are both caused by UV radiation from exposure to the sun. BCC is a localised skin cancer that grows slowly, while SCC grows more quickly and has a higher risk of spreading to deeper tissues, lymph nodes and other organs. 

“BCC and SCC tend to occur in sun-exposed areas, including the head and neck and hands,” explains Dr Patalay. “However, SCC also occurs in areas of chronic inflammation like wounds or ulcers, and may develop due to HPV infections or immunosuppression.” 

In terms of physical appearance, BCC can present as a bump that is shiny, pink or translucent and can also feature visible blood vessels. SCC typically presents as a rough or scaly red patch that might develop into an open sore or ulcer, or a solid growing lump. Both BCC and SCC can be treated with Mohs surgery, but prompt treatment is advised for SCC due to its more aggressive nature. 

What is Mohs surgery? 

Mohs micrographic surgery was first developed in the 1930s by Dr Frederic Mohs, after whom it is named. The procedure is highly specialised and involves removing the carcinoma layer by layer, with each sample sent to our dedicated on-site laboratory for assessment to determine whether any cancer is present. If any cancerous cells remain, the next layer of tissue is removed and investigated in the same way. This process is repeated until the surgeon reaches a layer with no cancerous cells. A Mohs surgeon typically removes between 1-3 layers before all cancer cells are eliminated, however, in some cases, it can be as many as 6 or 7 layers. 

The processing of each layer of tissue can take between 60 and 90 minutes. Typically, the patient and our team need to prepare to be in the clinic for the entire day and, although it may only take a morning, our Mohs surgeons cannot confirm that until each layer of tissue has been removed and examined individually. With our dermatology specialists dedicated to the patient for the entire day, they can leave after the procedure with the confidence that the cancer has been removed. 

“Mohs surgery is most often used to treat areas where you need to preserve as much normal skin as possible,” explains Dr Patalay. “Typically, that means the head and neck, where every millimetre counts, and we want to remove the minimum amount of healthy skin and conserve cosmesis and function.” 

Our Mohs surgery specialists are attached to Guy’s Hospital, which is home to St John’s Institute of Dermatology, a world-renowned centre for the treatment of skin conditions.  At Guy’s, we have the largest Mohs centre in the UK, seeing about 35 cases per week (compared to a national average of up to 10 cases per week) and treat the most complex BCC and SCC cases in the country. We’re pleased to now bring that expertise and our world-leading dermatology reputation to our state-of-the-art private facilities at Wimpole Street Consulting Rooms and Diagnostic Centre. 

Mohs surgeons routinely collaborate with plastic surgeons to remove the cancer and to manage reconstructive work following the carcinoma removal, if necessary. Dr Patalay says, “we work with other surgical specialties, including plastic and oculoplastic surgeons, to carry out any reconstructions required after the removal of the cancerous tissue, especially when multiple layers have been removed.”  

Benefits of Mohs surgery 

The availability of Mohs surgery is very limited due to needing a team of experts, all with specialist training, ranging from dermatology surgeons and plastic surgeons to nurses and laboratory technicians. However, Mohs surgery has numerous benefits including: 

• cure rate of up to 99% with low risk of recurrence 
• performed on an outpatient basis 
• preserves as much normal tissue as possible 
• surgeon ensures all cancer is removed in real-time 
• typically causes a smaller scar than standard excision surgery

As the minimum amount of skin is removed from the affected area, the post-surgery scars are much smaller than with standard surgery, which is critical for facial features like the lips, nose and eyelids, where every millimetre makes a difference. 

“The advantage is that if you try to treat tumours that are tracking under the skin, you are able to see how far they have spread with Mohs, which you can’t see with normal surgery,” explains Dr Patalay. “With those cases, in standard surgery the tumours get removed, but it takes several weeks to discover the tumour was not fully removed. The patient then requires a second, or sometimes even third, surgical procedure. Each time, you don’t know if you’re getting it all out because you can’t the edge of the tumour with the naked eye. This is where Mohs is a far superior treatment option.” 

When to refer to us 

Patients with basal or squamous carcinomas can be referred to our Mohs specialists for treatment of lesions on their head or neck, with the waiting time until treatment at around 6 weeks for private care at Wimpole Street Consulting Rooms and Diagnostic Centre. Up to 2 lesions can be treated in the same sitting if required. One of the main symptoms to be aware of is a non-healing lesion on the face. 

For lesions on other parts of the body, it’s possible that other treatment options, such as standard excisional surgery or radiation, are more suitable than Mohs as millimetre precise removal is less critical. Our team of specialists can advise on individual cases to create personalised treatment plans for patients. 

Get in touch 

For more information on Mohs micrographic surgery for removal of basal and squamous cell carcinomas, please contact our customer services team. Call 020 3131 5130 or email privatepatientenquiries@gstt.nhs.uk