What is a non-invasive method using liquid nitrogen (LN) for treating skin cancer other than melanoma?

Cryosurgery for Non-Melanoma Skin Cancer

Cryosurgery using liquid nitrogen is a well-established non-invasive treatment method for non-melanoma skin cancers, particularly effective for small, well-differentiated squamous cell carcinomas and superficial basal cell carcinomas when performed by experienced practitioners.

Treatment Technique and Protocol

The standard cryosurgery protocol involves:

• Application of liquid nitrogen using an open spray technique with a double freeze-thaw cycle 1, 2
• Temperature monitoring to reach -50°C to -60°C inside the tumor tissue 3, 2
• Maintaining at least -20°C at the tumor margins and underlying structures 3
• Use of thermocouples for temperature monitoring to ensure adequate tissue destruction 3, 2

Efficacy by Cancer Type

Basal Cell Carcinoma (BCC)

• Superficial BCCs respond well to cryosurgery, with 5-year cure rates of 99.0% reported in large series 2, 4
• Cryosurgery is at least as effective as other modalities for superficial BCCs, with superior cosmetic outcomes 1
• Nodular BCCs are less suitable for cryosurgery alone, though adjunctive curettage may improve results 1

Squamous Cell Carcinoma (SCC)

• Small (<1 cm), well-differentiated, primary SCCs on sun-exposed sites are appropriate for cryosurgery 1
• 5-year cure rates of 96.1% have been achieved for selected SCCs 4
• Caution is advised due to limited published data on larger tumors and the metastatic potential of SCC 1
• Prior biopsy is necessary to establish histologic diagnosis before treatment 1
• Cryosurgery is not appropriate for locally recurrent SCC 1

Clinical Outcomes

Cure Rates

• Overall 30-year cure rate of 98.6% across all non-melanoma skin cancers in experienced hands 2
• Recent 5-year cure rate of 99.0% in a series of 522 cases 2
• Overall cure rate of 88% for advanced SCCs of the extremities 3

Cosmetic Results

• Superior healing and cosmesis compared to other treatment modalities 1
• Pigmentary changes (both hypo- and hyperpigmentation) can occur, especially in darkly pigmented skin 5
• These pigmentary changes typically improve by 6-12 months 5

Healing Timeline

• Immediate post-treatment effects include vesicle formation, erythema, swelling, and burning pain 5
• Crusted eschar forms within days after treatment 5
• Complete healing typically occurs within several weeks 5
• Repeat treatments at 3-week intervals may be necessary for incomplete responses 5

Important Caveats and Limitations

Key limitations include:

• Significant variability in liquid nitrogen application techniques exists, particularly between North American and European practices 1
• Case selection is critical—high cure rates may reflect treatment of predominantly small, favorable tumors 1
• Cryosurgery should be avoided on eyelids, lips, nose, and ears due to potential complications 5
• No histologic confirmation of complete tumor removal is possible, unlike surgical excision 1
• Not recommended as first-line therapy when surgical options are feasible 6

When to Consider Cryosurgery

Appropriate clinical scenarios:

• Small, superficial BCCs where size, site, or number of lesions limit conventional therapy effectiveness 1
• Selected small, well-differentiated primary SCCs on sun-exposed sites in experienced hands 1
• Patients with contraindications to surgery or multiple lesions requiring simultaneous treatment 1
• Advanced extremity cancers where amputation would otherwise be necessary 3

Cryosurgery should only be performed by experienced practitioners at specialized centers, particularly for SCC treatment 1.