What is the treatment for actinic keratosis?

Treatment of Actinic Keratosis

For patients with actinic keratosis, field-directed treatment with 5-fluorouracil (5-FU) or imiquimod is strongly recommended as first-line therapy, with cryosurgery recommended for isolated lesions. 1

Understanding Actinic Keratosis

Actinic keratosis (AK) consists of rough scaly patches that develop on chronically sun-exposed skin. These lesions represent an early stage in the evolution of squamous cell carcinoma (SCC), with progression rates varying from less than 0.1% to 20%. Studies examining SCC histologically have found adjacent contiguous AK in more than 60% of cases 1.

Key characteristics:

• Typically appears on sun-exposed areas (face, scalp, neck, hands, forearms)
• Represents a field of cancerization with both visible and subclinical lesions
• Has variable spontaneous regression rates (15-63% per year)
• Can recur after regression (up to 50% within first year) 1

Treatment Approach

Treatment selection should be based on:

1. AK features (location, number of lesions)
2. Treatment-related factors (efficacy, tolerability)
3. Risk of progression to SCC

Field-Directed vs. Lesion-Directed Approach

Field-Directed Treatment

Recommended for multiple AKs in a contiguous area to address both visible and subclinical lesions:

1. 5-Fluorouracil (5-FU) - STRONG RECOMMENDATION (Moderate quality evidence) 1

   • Most effective field treatment
   • Decreases 1-year SCC risk by 75% (95% CI, 35-91; P = .002)
   • Typically applied as a 2-4 week course

2. Imiquimod - STRONG RECOMMENDATION (Moderate quality evidence) 1

   • Effective field treatment
   • Lower progression rate to invasive SCC (1.7%) compared to other treatments

3. Diclofenac 3% gel - CONDITIONAL RECOMMENDATION (Low quality evidence) 1

   • Note: Carries black box warning for cardiovascular and gastrointestinal side effects

4. Photodynamic Therapy (PDT) - CONDITIONAL RECOMMENDATION (Low to Moderate quality evidence) 1

   • Options include:
     • ALA-red light PDT
     • ALA-daylight PDT (less painful but equally effective)
     • ALA-blue light PDT
   • FDA approved: Aminolevulinic acid (AMELUZ) with BF-RhodoLED or RhodoLED XL lamp for mild-to-moderate AKs on face and scalp 2
   • Common adverse effects: erythema, pain/burning, irritation, edema (occurring in >90% of patients) 2

Lesion-Directed Treatment

Recommended for few or isolated AKs:

1. Cryosurgery - STRONG RECOMMENDATION (Good Practice Statement) 1

   • Standard treatment for isolated lesions
   • Quick in-office procedure
   • Conditionally recommended over CO2 laser ablation

2. Combination Approaches

   • 5-FU + cryosurgery is conditionally recommended over cryosurgery alone 1

Special Considerations

1. High-Risk Anatomical Locations

   • Periorbital region, ears, lips require more aggressive treatment due to higher risk of transformation 3

2. High-Risk Patients

   • Organ transplant recipients, immunosuppressed patients, and those with chronic lymphocytic leukemia require more aggressive treatment and closer follow-up 3

3. Prevention

   • UV protection is strongly recommended for all patients with AK 1
   • Continuous use of sunscreen and protective clothing is essential 4

Common Pitfalls and Caveats

1. Undertreatment of Field Cancerization

   • Treating only visible lesions while ignoring subclinical lesions in the surrounding field can lead to recurrence and progression 5
   • Field-directed therapies should be prioritized when multiple lesions are present

2. Patient Tolerability Issues

   • Field treatments often cause significant local skin reactions
   • Severe pain/burning occurs in up to 30-41% of patients using topical treatments or PDT 2
   • These reactions may lead to treatment discontinuation if patients aren't properly counseled

3. Observation Without Treatment

   • While observation may be considered in patients with limited life expectancy, most AKs should be treated due to risk of progression to SCC 1

4. Follow-up

   • Regular follow-up is essential as AKs have high recurrence rates
   • Patients with extensive sun damage require ongoing surveillance

Treatment Algorithm

1. For isolated/few AKs:

   • Cryosurgery as first-line treatment
   • Consider surgical options for suspicious or treatment-resistant lesions

2. For multiple AKs or field cancerization:

   • First-line: 5-FU or imiquimod
   • Second-line: Diclofenac 3% gel or PDT
   • Consider combination therapy (e.g., 5-FU + cryosurgery) for resistant cases

3. For all patients:

   • Implement strict UV protection measures
   • Schedule regular follow-up examinations

By following this evidence-based approach, clinicians can effectively manage actinic keratosis and potentially reduce the risk of progression to invasive squamous cell carcinoma.