Cryotherapy destroys cells by freezing them. It is useful for treating shallow and flat skin lesions such as superficial skin cancers, solar keratoses, lentigines and some seborrhoeic keratoses.
Freezing at an extremely low temperature destroys cells. The damage is similar to burning. To freeze the cells, cryotherapy uses liquid nitrogen (about -196°). The nitrogen is applied either by spraying with a special gun, or dabbing with a cotton bud. This process causes water in the cells to freeze and expand, breaking the cell wall and destroying the cell. This effect applies to both normal and abnormal cells in the treated area. It leads to to redness and sometimes blisters and sores.
When the sore heals, the original skin lesion is no longer present; the aim of cryotherapy is for it to be replaced by new healthy and normal skin cells.
Cryotherapy treats only individual spots. It cannot repair large areas of sun damaged skin. This means that the treated area may still be likely to develop further sun-related problems in future.
Cryotherapy (freezing) is a simple and effective treatment for solar keratoses.
The doctor treats individual solar keratoses for 15-20 seconds each. This treatment has a high success rate and is relatively quick and inexpensive.
Cryotherapy is a good first-line treatment for solar keratoses because:
If there are many solar keratoses (more than 20 or so), cryotherapy may not be the best treatment because:
If you have many solar keratoses, treatment with a cream such as fluorouracil/calcipotriol, imiquimod (Aldara), diclofenac (Solaraze) or fluorouracil (Efudix) may be a better alternative to cryotherapy.
Very shallow skin cancers such as superficial basal cell carcinoma and Bowen's disease (superficial squamous cell carcinoma) often respond well to treatment with cryotherapy, avoiding the need for an excision and stitches.
Because cryotherapy might not penetrate the full thickness of the skin, it should not be used to treat skin cancer unless a biopsy has already confirmed that the skin cancer affects only the uppermost levels of the skin. If a thicker skin cancer is treated with cryotherapy, the top of the skin cancer might appear to be cured while deeper cells continue to spread and cause damage not visible from the surface.
The skin cancer and a margin of 2-3mm around it are treated by repeatedly freezing for 30 seconds and and thawing (three cycles). This is a stronger and more painful treatment than cryotherapy for solar keratoses, and your doctor may perform it under a local anaesthetic to reduce discomfort.
Side effects such as blistering, pain and scarring are common.
The success rate of treatment with cryotherapy is variable:
This means that in some cases the lesion may not go away, or it might reappear after treatment. But if sun spots reappear after treatment, it does not necessarily mean the treatment has failed. Sun spots are likely to continue to develop in areas of sun damaged skin for the rest of your life.
if you have had a basal cell carcinoma or squamous cell carcinoma treated, it is important to have the area checked later to confirm that the treatment was successful
Cells that produce skin pigment can be destroyed by cryotherapy, causing a permanent pale area at the site of treatment. This reaction is common, but usually hard to notice in fair-skinned people. People with darker skin should be aware of the risk of reduced skin pigmentation before having cryotherapy.
In some cases, the amount of skin pigmentation can increase after cryotherapy, due to inflammation. This usually settles gradually but in some cases can be permanent.
Cryotherapy to hairy areas can result in permanent hair loss. For this reason, we often avoid cryotherapy treatment in the area of the eyebrows and on the hairline. Other options such as prescription creams may be better treatments in these areas.
In regions with poor circulation (typically the lower leg), cryotherapy can cause ulcers (open sores) which take a long time to heal and may be at risk of infection. Alternative treatments such as surgical removal or applying a cream may be better treatments for BCC, SCC or solar keratoses in these areas, particularly in people with vascular problems or diabetes.
A doctor or nurse applies liquid nitrogen to the area to be treated. This is done either by spraying liquid nitrogen from a canister or applying with a cotton bud or other applicator. The treated area is usually kept frozen for 30 seconds. When skin cancers are treated, three 30-second cycles are applied.
Blistering, sores, infection, scarring, hypopigmentation (treated area becomes pale or white), hyperpigmentation (treated area becomes darker), pain, headache, treatment failure
For cosmetic treatments or treatment of low-risk lesions such as solar keratoses, formal follow-up may not be required. If a skin cancer is being treated, the doctor may request that you return for re-examination after the treated area has healed.
History of hyper/hypopigmentation following cryotherapy
Cryotherapy is not a suitable treatment for most skin cancers or moles.
Some early skin cancers affect only the top layers of the skin. Although they can be removed surgically, there are other methods of treatment which may offer advantages such as less scarring or expense.