- 1 Background
- 2 Overview of evidence (non-systematic literature review)
- 2.1 Cryotherapy for cutaneous squamous cell carcinoma and related tumours
- 2.2 Electrodessication and curettage for cSCC
- 3 Practice Point
- 4 References
Cutaneous squamous cell carcinomas (cSCCs) are very common in Australia and are the second most common skin cancer. Small superficial and well-differentiated cSCCs in low risk sites can be adequately treated with cryotherapy or electrodessication and curettage (EDC).
Relative indications of cryotherapy and EDC for cSCC and related lesions include:
- Bowen’s diseasecSCC in situ (also known as intra-epidermal SCC), especially on trunk or limbs
- cSCCs of low-risk type, especially on the trunk and limbs
- the treatment of lesions in elderly patients, especially those with medical disorders less tolerant of surgical procedures (e.g. those with pacemakers or coagulopathies)
- in geographic areas with poor access to surgical facilities
- palliation of inoperable tumours.
Cryotherapy may be appropriate for lesions at body sites with increased risk of keloid scars from other treatment modalities (e.g. curettage or surgical excision on the upper arms and upper trunk).
Relative contraindications of cryotherapy and EDC for cSCC and related lesions include:
- cosmetically sensitive sites, especially face and neck in younger patients
- high-risk body sites, especially on face and neck (i.e. sites where it is difficult to ascertain depth of tumour penetration or where deep recurrence poses greater potential risks)
- high-risk tumour categories (i.e. ill-defined or sclerosingscar-like (morphoeic) BCC and moderately to poorly differentiated cSCC)
- recurrent cancers for which surgical excision with histological confirmation of clear margins is essential.
With the increasing number of organ transplant patients developing very large numbers of cSCCs, the use of EDC in selected tumours can be of value where surgical excision may be impractical.
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Overview of evidence (non-systematic literature review)
Cryotherapy produces cure rates equivalent to other standard treatment modalities for low-risk cSCCs on the trunk and limbs.
Small (<1cm) well-differentiated cSCC in low-risk areas can often be adequately treated with cryotherapy.
Bowen’s diseasecSCC in situ (also known as intra-epidermal SCC) (cSCC in situ) can be often adequately treated with cryotherapy.
No randomised controlled studies have compared cryotherapy with surgery or other treatment approaches in the treatment of cSCC. Observational studies such as case series have reported outcomes of EDC in the treatment of cSCC.[references]]
Cryotherapy for cutaneous squamous cell carcinoma
Low-risk cSCCs can be treated by cryosurgery. It may be indicated for small primary well-defined and non-ulcerated tumours on the trunk and limbs, for which acceptable cure rates have been reported. In general, less-well differentiated cSCCs, recurrent cSCCs and those on the head and neck are better treated by surgical excision or radiotherapy.
Histological confirmation and analysis for high-risk features is essential prior to cryosurgery.
In general, low-risk tumours are selected. The criteria for such cSCCs include:
- primary tumour
- small size
- well defined
- clinically and histologically well differentiated
- on trunk or limbs.
Even with strict selection criteria in experienced clinics, there are some recurrences following cryosurgery for head and neck lesions, in contrast to the very rare recurrences for those on the trunk and limbs. Cryosurgical management of SCC on the head and neck should generally be limited to specialist clinics with the full range of treatment options available.
Cryotherapy for actinic keratoses
Actinic (solar) keratoses (AKs) are common skin lesions displaying different clinical and histological features. They represent both markers of actinic damage and potential precursors of cSCCs.
A continuum of clinical and histological dysplasia occurs from AK to Bowen’s diseasecSCC in situ (also known as intra-epidermal SCC) (cSCC in situ ) and invasive cSCC. However, not all AKs progress to SCC and some can regress spontaneously or following routine use of sunscreen application. No clinical feature of AKs predicts which will become malignant. However, increased erythema, thickening, alteration or changes in size may indicate early progression to cSCC. The risk of cSCC may be greater for immunosuppressed patients.
The diagnosis of AK is usually made clinically, but biopsy may be indicated to exclude malignancy.
Actinic keratoses may be treated for cosmetic reasons, due to irritation, or because of the potential for developing cSCC.
Topical 5 Fluorouracil cream may be used initially to highlight subclinical keratoses prior to cryotherapy treatment.
Successful clearance of AKs using cryotherapy with good cosmetic results requires accurate diagnosis and adequately timed treatment protocols. A single freeze–thaw cycle is usually recommended. Cure rates ranging from 69% to greater than 98.8% have been reported. Response rates tend to parallel the duration of the freeze time.
Hyperkeratotic or suspicious AKs may be better treated by curettage alone, or curettage followed by cryotherapy, EDC or ablative laser to the base. These techniques provide a specimen for histological confirmation.
A range of topical therapies can be used to reduce signs of photodamage and to treat established and preclinical actinic keratoses. These include chemical peeling, dermabrasion, laser resurfacing, alpha-hydroxy acids and retinoid formulations, diclofenac 3% in hyaluronic acid 2.5% gel, imiquimod 5% cream, ingenol mebutate, and photodynamic therapy.
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Cryotherapy for Bowen’s diseasecSCC in situ (also known as intra-epidermal SCC) (cSCC in situ)
Bowen’s diseasecSCC in situ (also known as intra-epidermal SCC) (cSCC in situ) is not invasive and does not need to be treated in the same manner as cSCC. Bowen’s diseasecSCC in situ (also known as intra-epidermal SCC) has been treated successfully with cryosurgery, with many studies reporting greater than 95% cure rates and reasonable follow-up periods. Suboptimal treatment protocols produce less satisfactory results. A pre-treatment biopsy is usually recommended.
A single freeze-thaw treatment cycle of 30 seconds with a 3mm margin is advised. Slow healing was reported for lesions greater than 20mm in diameter and for those on the lower legs. Cure rates greater than 99% are achieved with optimal cryotherapy consisting of liquid nitrogen used in an open spray technique with a single freeze cycle of 30 seconds or greater, achieving a minimal 3mm freeze halo around the marked lesion. Cure rates vary from 66% to 97% with less aggressive protocols.
Anatomical site does not appear to affect response to cryotherapy.
Cryotherapy for keratoacanthoma
Larger lesions are often removed by curettage (providing a specimen for histology) followed by double freeze–thaw cycle cryotherapy to the base of the lesion.
Few studies have investigated outcomes of cryotherapy for keratoacanthomas. A cure rate of 87.5% was achieved in one series of five lesions on the head and neck and three lesions on the trunk and limbs. Double freeze–thaw cycles of 30 seconds or more with 3–5 mm treatment margins were used. Site differences in response to cryotherapy have not been noted in the small series reported. Size appears to have been a factor in the choice of cryotherapy, with almost all treated lesions less than 20mms in diameter. One large keratoacanthoma responded to cryotherapy after initial shave excision.(See: Clinical features of cutaneous squamous cell carcinoma).
Electrodessication and curettage for cSCC
There is little evidence to determine the role of EDC in the management of cSCC and there is no international clinical consensus on its use.
No randomised controlled studies have compared EDC with surgery or other treatment approaches in the treatment of cSCC and related lesions. Observational studies such as case series have reported outcomes of EDC in the treatment of cSCC.\Electrodessication and curettage should only be performed by operators with appropriate supervised training in the procedures.
EDC for cutaneous squamous cell carcinoma
One study demonstrated a cure rate of 96% in a group of 48 patients followed for 5 years and 98% in a group of 101 patients observed over 4 years. In both groups selection was based on a lesion size of less than 2cm and ‘unusually invasive, destructive, or sclerosingscar-like (morphoeic)’ lesions were treated by irradiation or surgery.
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EDC for Bowen’s diseasecSCC in situ (also known as intra-epidermal SCC) (cSCC in situ)
Electrodessication and curettage is one of a number of modalities used by dermatologists in the management of Bowen’s diseasecSCC in situ (also known as intra-epidermal SCC) on exposed areas. The technique requires that the skin be stabilised by stretching to provide a firm base against which to curette.
It is also important that the dermis does allow the curette to break through to the deeper tissues. This limitation precludes the use of the technique on eyelids, the genital area or lip.
As many cases occur on the legs of elderly patients, this method has the advantage of not requiring reconstruction.Published data are limited to retrospective, uncontrolled studies with inadequate follow-up. These studies report recurrence rates ranging from 6.25% to 20%.
EDC for keratoacanthoma
Keratoacanthoma may be considered a relatively benign tumour and is commonly treated by dermatologists using the EDC technique.
Electrodessication and curettage seems an acceptable procedure for keratoacanthoma, provided that:
- it has not been previously treated
- it is not on the ear or lip
- it is less than 1cm in diameter on other parts of the head
- it strictly satisfies the clinical diagnostic criteria for keratoacanthoma
- the curette is used to obtain the largest and deepest single piece of tissue possible for histology and the report is consistent with the diagnosis
- close follow-up can be achieved with immediate excision at the first sign of recurrence
- it is carried out by operators with appropriate supervised training in the procedure.
Electrodessication and curettage is not appropriate for:
- lesions in high-risk areas (nasal, paranasal, lips, eyelids, chin, jawline and ears), or at least not for lesions larger than 5mm at these sites
- lesions larger than 10mm on moderate-risk sites (face, forehead, temples and scalp)
- lesion of any size on low-risk areas (neck, trunk and limbs).
- clinically sclerosingscar-like (morphoeic) lesions.
- recurrent lesions.
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PP 9.2.1. Cryotherapy is contraindicated for recurrent cutaneous squamous cell carcinoma.
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