The spray-gun is a common sight at skin cancer clinics!

What is Cryotherapy?

Cryotherapy is freezing treatment & often used in the skin cancer clinic.  The temperate of Liquid nitrogen is -195.6°C. The skin cells are damaged both during the freezing treatment itself and the thaw. Different types of skin cell and skin cancer cell are killed at different temperatures.

The lesion freezes from the centre outwards. The skin directly under the targeted area is frozen at a deeper level than the skin at the edge of the frozen area.

How do does the skin cancer doctor know deep the freeze is going? By looking at the ice circle on the surface – the wider the ice circle, the deeper will be the freeze.

What affects the amount of tissue frozen?

The most common technique of cryotherapy is spraying liquid nitrogen directly onto the lesion via a fine spray. The following factors influence how much tissue is frozen and at what depth:

    • How quickly the lesion is frozen
    • How long the lesion is frozen for (eg 5-15 seconds for solar keratosis, 30-60 seconds for malignant)
    • Shorter frequent bursts of spray .V. Longer less frequent sprays
    • The number of “cycles” of cryotherapy (one is enough for solar keratosis, two or more cycles are used for actual skin cancers)
    • The time between cycles

As you can see, technique is important. It looks simple but the technique does involve attention to detail.

What is Cryotherapy used for?

Cryotherapy is used to treat a huge variety of skin lesions including some types of skin cancer. The most common lesions treated are:

    • Solar Keratosis (by far the most common indication in a skin cancer clinic)
    • Viral Wart

What are the side effects of Cryotherapy?

The procedure is normally well tolerated. However, deeper freezes required for large or malignant lesions may have significant side effects

    • Discomfort or pain – for longer freeze times, or treatment of sites that are more tender (especially the ear). When pain occurs, it’s usually during the thawing stage.
    • Soreness, Redness, Blister, Crusting, Swelling. Blisters are best left intact. Scabs should not be removed as they help to protect the healing wound and will fall off after a few weeks.
    • Pigmentation after the procedure: usually loss of pigment but there may be increased pigment on occasion. Uncommonly,  the pigmentation is permanent.

Also you could add wound recovery time for long freezes required for skin cancer: a month or more – the long freeze required for skin cancers such as BCC or IEC is not an “easy” option.

Why has my skin gone pale after Cryotherapy?

Different types of skin cancer cells are killed at different temperatures.

Melanocytes are the pigment-carrying skin cells. Unfortunately, melanocytes are killed at lower temperatures than most other types of skin cell including all the types of cell which are being targeted during cryotherapy. Therefore, pale patches are common after cryotherapy.

There is an argument that cryotherapy that does not kill melanocytes (with loss of skin pigment) is unlikely to be doing much good.

The Pros & Cons of Cryotherapy for Solar Keratosis & Skin Cancers

  • Cryotherapy for Skin Cancer Pros

    Cryotherapy is quick to perform and therefore does not require an additional appointment.

    The resulting scar tends to be better than surgical excision.

  • Cryotherapy for Skin Cancer Cons

    No Pathology Sample & Pathology is may be required for confirmation. Cryotherapy is only suitable for two types of skin cancer: IEC & BCC. Longer freezes required with a recovery time of a month or so. Skin cancer recurrence rate usually higher compared with surgery.

WRITTEN BY: Dr Richard Beatty