What is the evidence for treating Bowen's disease with cryotherapy using a cryopen?

Evidence for Treating Bowen's Disease with Cryotherapy (Cryopen)

Cryotherapy is effective for treating Bowen's disease but has higher complication rates and lower single-treatment clearance rates compared to other treatment modalities like photodynamic therapy (PDT) and curettage. 1

Efficacy of Cryotherapy for Bowen's Disease

Clearance Rates

• Cryotherapy can achieve 100% clearance with 1-3 treatments of liquid nitrogen using a single freeze-thaw cycle of 20 seconds 1
• Initial clearance after a single treatment is approximately 50% 1, 2
• Recurrence rate is approximately 10% at 12 months follow-up 1

Comparison with Other Treatment Modalities

Cryotherapy vs. PDT

• PDT demonstrated significantly higher clearance rates after a single treatment (75% vs. 50%) compared to cryotherapy 1
• In a randomized study of 40 lesions, PDT cleared 15/20 lesions after one treatment, while cryotherapy cleared only 10/20 lesions after one treatment (p<0.01) 2
• PDT showed superior cosmetic outcomes compared to cryotherapy 1

Cryotherapy vs. Curettage

• In a prospective non-randomized trial comparing curettage and cautery (44 lesions) with cryotherapy (36 lesions):
  • Median healing time: 46 days with cryotherapy vs. 35 days with curettage 1, 3
  • For lower leg lesions: 90 days with cryotherapy vs. 39 days with curettage (p<0.001) 3
  • Recurrence rates: 13/44 with cryotherapy vs. 4/36 with curettage during 2 years follow-up 1
  • Pain was significantly greater with cryotherapy 1, 3

Adverse Effects of Cryotherapy

Cryotherapy is associated with several adverse effects:

• Ulceration (25% of lesions) 1, 2
• Infection (10% of cases) 2
• Scar formation (20% of cases) 1
• Prolonged healing time, especially on lower leg 1, 3
• Significant pain during and after treatment 3

Technique for Cryotherapy Application

For adequate treatment, the following techniques are recommended:

• Liquid nitrogen cryotherapy using:
  • A single freeze-thaw cycle of 30 seconds, or
  • Two freeze-thaw cycles of 20 seconds with a thaw period, or
  • Up to three single treatments of 20 seconds at intervals of several weeks 1

Special Considerations

Anatomical Location

• Lower leg lesions heal particularly slowly with cryotherapy (median 90 days) 3
• Cryotherapy may be less suitable for:
  • Large or multiple lesions
  • Poor healing sites like the lower leg
  • Penile, digital, and facial lesions 1

Lesion Size

• Healing may be slow for broad lesions 1
• Discomfort may limit treatment of multiple lesions 1

Novel Approaches

A newer approach called immunocryosurgery (combining imiquimod with cryotherapy) has shown promising results:

• 100% clearance rate in a study of 24 lesions
• 91.7% sustained complete remission after median follow-up of 24 months
• Satisfactory cosmetic outcome except for variable hypopigmentation 4

Conclusion

While cryotherapy is effective for treating Bowen's disease with adequate treatment protocols, the evidence suggests it has limitations compared to other treatment modalities. PDT demonstrates higher single-treatment clearance rates and better cosmetic outcomes, while curettage shows faster healing times and less pain. The British Association of Dermatologists guidelines indicate that PDT may offer advantages over cryotherapy, particularly for large or multiple lesions and those in poor healing sites 1.