Treatment Options for Actinic Keratosis on the Ear and Cheek

Introduction to Treatment Guidelines

• The American Academy of Dermatology recommends cryosurgery for isolated lesions or field-directed therapy with 5-fluorouracil or imiquimod for multiple lesions as first-line treatments for actinic keratosis on the ear and cheek, based on the 2021 guidelines 1, 2

Treatment Selection Based on Lesion Characteristics

• Cryosurgery is strongly recommended as first-line treatment for isolated actinic keratoses on the ear and cheek, with high efficacy and convenience of a single office visit 3
• Curettage may be warranted for thicker actinic keratoses on the ear, especially when there is suspicion of early squamous cell carcinoma, and histology must always be obtained 4

Field-Directed Therapy

• Field-directed therapy is recommended when multiple actinic keratoses are present in a contiguous area 1
• The American Academy of Dermatology strongly recommends 5-fluorouracil and imiquimod for field treatment, with 5-fluorouracil having the highest efficacy rating 3, 5

Treatment Considerations for Specific Sites

• The ear requires special consideration due to higher risk of metastasis when squamous cell carcinoma develops at this site 4
• The American Academy of Dermatology recommends cryosurgery, 5-fluorouracil, and imiquimod for facial lesions, with excellent ratings 6, 7

Combination Approaches

• The combined use of 5-fluorouracil and cryosurgery is conditionally recommended over cryosurgery alone, with moderate quality evidence 3
• The combined use of imiquimod and cryosurgery is conditionally recommended over cryosurgery alone, with low quality evidence 3

Treatment Algorithms

• For isolated lesions, the American Academy of Dermatology recommends cryosurgery with liquid nitrogen as first-line treatment 3
• For multiple lesions, the American Academy of Dermatology recommends 5-fluorouracil or imiquimod as first-line field therapy 3

Important Considerations and Pitfalls

• Actinic keratoses have a recurrence rate estimated to be as high as 50% within the first year, necessitating ongoing monitoring and treatment 1
• The risk of progression of actinic keratosis to squamous cell carcinoma varies from less than 0.1% to 20%, with higher risk on the ear 5
• The American Academy of Dermatology strongly recommends UV protection for all patients with actinic keratoses to prevent new lesions 3
• Patient factors, including compliance and ability to tolerate side effects, should be considered when selecting treatment 2

Treatment of Actinic Keratosis

Lesion-Directed Treatments

• Cryosurgery is strongly recommended as first-line treatment for isolated actinic keratoses on the face, with clearance rates between 57% and 98.8% depending on follow-up duration, and longer freeze times (>20 seconds) achieve higher clearance rates (83%) compared to shorter freeze times (<5 seconds, 39% clearance), according to the American Academy of Dermatology 8
• Photodynamic therapy (PDT) with ALA-red light has complete clearance rates of 77.1% at 12 weeks, as recommended by the American Academy of Dermatology 8

Field-Directed Treatments

• Tirbanibulin is strongly recommended with high certainty evidence, applied once daily for 5 consecutive days with complete clearance rates of 49.3% at day 57, and has the advantage of a much shorter treatment duration compared to other topical agents, as stated by the American Academy of Dermatology 9, 10, 11
• Photodynamic therapy (PDT) with ALA-blue light is conditionally recommended with moderate quality evidence, according to the American Academy of Dermatology 12
• Photodynamic therapy (PDT) with ALA-daylight is conditionally recommended as less painful but equally effective as ALA-red light PDT, as recommended by the American Academy of Dermatology 12

Combination Approaches

• 5-FU + Cryosurgery is conditionally recommended over cryosurgery alone with moderate quality evidence, according to the American Academy of Dermatology 12
• Imiquimod + Cryosurgery is conditionally recommended over cryosurgery alone with low quality evidence, as stated by the American Academy of Dermatology 12
• Diclofenac + Cryosurgery is conditionally recommended against compared to cryosurgery alone, according to the American Academy of Dermatology 12

Photodynamic Therapy as First‑Line Treatment for Early Actinic Keratosis in Elderly Patients

Efficacy and Evidence Strength

• Photodynamic therapy (PDT) clears 69‑91 % of actinic keratoses and consistently yields excellent cosmetic results, outperforming most alternative modalities. Strength A, level 1+ evidence from the British Association of Dermatologists supports its use. 13
• Daylight PDT specifically achieves clearance rates of 70‑89 % for mild‑to‑moderate facial and scalp lesions in five randomized controlled trials, with virtually no pain reported during the 2‑hour exposure. 14
• For early (grade 1‑2) actinic keratoses, daylight PDT is recommended as first‑line therapy, providing 70‑89 % clearance and minimal discomfort, which is especially advantageous for patients with limited tolerance for invasive procedures. 14

Practical Protocol and Advantages of Daylight PDT

• The daylight PDT protocol involves applying high‑SPF sunscreen (without mineral filters) 15 minutes before methyl aminolevulinate (MAL) cream, leaving the cream uncovered, and then exposing the treated area to ambient daylight for 2 hours; this can be performed in any weather when temperature exceeds 10 °C. 14
• The procedure is nearly pain‑free compared with conventional PDT, making it suitable for elderly individuals who may experience heightened sensitivity to treatment‑related discomfort. 14
• Follow‑up evaluation at 3 months post‑treatment is advised to assess response and identify early recurrences. 14

Comparative Effectiveness of Alternative Therapies

• Cryosurgery: Provides a 75 % complete response at 3 months overall, but clearance for superficial lesions (~52 %) is lower than PDT (≈69‑91 %). It also carries a notable risk of hypopigmentation and scarring, which are more problematic in elderly patients with fragile skin. [15][13]
• Topical 5‑fluorouracil (5‑FU): Achieves 70‑73 % clearance at 6 months for field‑directed treatment but requires twice‑daily application for 4 weeks and commonly causes significant local inflammation, potentially limiting adherence in older patients. [15][16]
• Imiquimod: Better tolerated than 5‑FU yet still necessitates several weeks of application, posing compliance challenges for very elderly individuals. [13][16]
• Topical tretinoin: Results in only a 30.3 % reduction in actinic keratoses after 16 weeks and is not recommended as monotherapy. [15][17]

Safety, Cosmetic Outcomes, and Long‑Term Considerations

• PDT is associated with excellent cosmetic outcomes across lesion types and anatomical sites, with clinically evident scarring being rare. 16
• Long‑term safety data show an extremely low risk of PDT‑induced skin cancers; over 25 years of use, only two possible tumor inductions have been reported. 16
• When ambient temperature is consistently below 10 °C, conventional red‑light PDT should replace daylight PDT to maintain efficacy. 14

Recommendations on Therapies to Avoid in Elderly Patients

• Cryosurgery, ablative laser therapy (CO₂, Er:YAG), and topical tretinoin should not be used as first‑line options for early actinic keratoses in elderly patients due to higher rates of scarring, hypopigmentation, and limited effectiveness. [13][14]15