Neubert 2008 - BJPS - Bowen disease

Summary

• Bowen's disease is squamous cell carcinoma (SCC) in situ with 3-5% risk of progression to invasive SCC. Incidence in Caucasians is 1.42 per 1000.

• Multiple etiological factors identified including UV radiation, arsenic exposure, immunosuppression, HPV infection.

• Lesions commonly occur on lower legs and head/neck. Can also be subungual, palmar, genital, perianal.

Established Treatments

• Cryotherapy: Liquid nitrogen preferred. Clearance rates 50-100%, recurrence 10-36%. Better for small, well-healing lesions. Side effects include poor cosmesis, prolonged healing.

• Curettage/Cautery: Clearance 81-98%, recurrence 4-13%. Faster healing than cryotherapy. Best for small, single lesions.

• Surgical Excision: Clearance over 90%, recurrence up to 19% except for perianal (53% recurrence). Tissue sparing possible with Mohs. Mainly for small solitary lesions.

• Topical 5-Fluorouracil: Clearance 67-96% with prolonged application. Often combined with other modalities. Side effects include inflammation, erosion, ulceration.

• Radiotherapy: 94-100% clearance but not for lower legs (poor healing). Toxicity risk with some techniques. Alternative is radioactive holmium-166 skin patches.

• Laser Therapy: Good outcomes for penis/digit lesions with CO2 laser. Data limited to case reports/series.

• Overall similar efficacy across modalities, choice depends on factors like lesion site, patient age and comorbidities.

Newer Treatments

• Topical Diclofenac: 7 published cases show 100% clearance, mild side effects. Inhibits tumor-promoting COX enzymes and arachidonic acid metabolites. Further studies needed.

• Topical Imiquimod: Immunomodulator. Studies show 75-93% clearance but frequent local reactions. May have added antiviral effect. Further studies needed on optimal dosing.

• Photodynamic Therapy: Light activated cytotoxicity using aminolevulinic acid or methyl aminolevulinate. Shows 88-100% clearance, excellent cosmesis. Main side effect is pain. Some guidelines recommend as first line.

Conclusion

• No single superior treatment. Choice depends on lesion/patient factors, physician experience, patient preference.

• Monitoring needed given recurrence risk with most therapies.

• Newer therapies like diclofenac, imiquimod and PDT emerging as effective options but more evidence needed.