Fractional Photothermolysis for Facial Actinic Keratosis
Fractional Photothermolysis for Facial Actinic Keratosis
Katz TM, Goldberg LH, Marquez D, et al
J Am Acad Dermatol. 2011;65:349-356
Actinic keratosis (AK) is the most common precancerous cutaneous lesion that is characterized clinically by photodistributed, erythematous, scaling macules and papules and histologically by partial-thickness keratinocytic dysplasia. Treatments include liquid nitrogen cryosurgery, topical chemotherapy, ablative laser surgery, and photodynamic therapy. Traditional ablative laser treatments (eg, carbon dioxide, erbium) yield up to 94% clinical reduction in facial AK with lower histologic clearance rates. However, full-face resurfacing is associated with significant pain, erythema, prolonged recovery times, and the potential for complications such as dyspigmentation, infection, and scarring. In contrast, fractional photothermolysis (FP) produces pixel-like columns of deep thermal injury, leaving islands of undamaged keratinocytes and thereby minimizing downtime. Popular uses for FP include treatment of chronic solar photodamage, acne scarring, and epidermal dyspigmentation.
FP has not been advocated as a mainstream monotherapy for AK and cutaneous malignancies, in part because "skip areas" of keratinocytic atypia would intuitively limit treatment efficacy. In order to test whether this is true, Katz and colleagues evaluated the efficacy of FP using a popular 1550-nm fractionated erbium-doped fiber laser to treat facial AK. This small pilot study was not blinded, had no controls, and included 14 men (59-79 years of age, Fitzpatrick Skin Phototypes I and II, mean facial AK count = 22.1) who received 5 laser treatments at 2- to 4-week intervals. Investigators assessed both clinical and histologic resolution of AK at 1 month, 3 months, and 6 months after the final laser treatment. The study design included a 1-month wash-out period for all AK treatments (eg, cryotherapy, topical chemotherapy, photodynamic therapy) and a 3-month wash-out period for topical retinoids and corticosteroids. Most FP treatments were performed at treatment level 11, 70 mJ, 8-10 passes, covering 32%-40% of facial surface area per treatment. Representative AK were biopsied from each patient prior to the first laser treatment and adjacent skin was biopsied at 3 months.
The key results of this study were as follows:
Although this study was small and lacked a control group, it still yielded an important conclusion: FP is a poor stand-alone treatment for facial AK. Not only did clinical response rates diminish over a 6-month follow-up period, but FP failed to clear the vast majority of AK histologically, even after 5 treatments at relatively aggressive settings. Furthermore, FP treatments did not prevent some AK from progressing to squamous cell carcinoma during the follow-up period. In contrast, FP didreduce clinical and histologic signs of chronic photodamage such as solar elastosis.
It should be noted that this study used only one type of laser and did not explore the efficacy of other fractional nonablative and ablative devices. Furthermore, Katz and colleagues correctly pointed out that FP may still have a role in the treatment of facial AK, perhaps as a means to enhance topical chemotherapy or photodynamic therapy by enhancing epidermal penetration. Future studies should continue to address this potential augmenting role.
Abstract
Nonablative Fractional Photothermolysis for Facial Actinic Keratoses: 6-Month Follow-up With Histologic Evaluation
Katz TM, Goldberg LH, Marquez D, et al
J Am Acad Dermatol. 2011;65:349-356
Study Summary
Actinic keratosis (AK) is the most common precancerous cutaneous lesion that is characterized clinically by photodistributed, erythematous, scaling macules and papules and histologically by partial-thickness keratinocytic dysplasia. Treatments include liquid nitrogen cryosurgery, topical chemotherapy, ablative laser surgery, and photodynamic therapy. Traditional ablative laser treatments (eg, carbon dioxide, erbium) yield up to 94% clinical reduction in facial AK with lower histologic clearance rates. However, full-face resurfacing is associated with significant pain, erythema, prolonged recovery times, and the potential for complications such as dyspigmentation, infection, and scarring. In contrast, fractional photothermolysis (FP) produces pixel-like columns of deep thermal injury, leaving islands of undamaged keratinocytes and thereby minimizing downtime. Popular uses for FP include treatment of chronic solar photodamage, acne scarring, and epidermal dyspigmentation.
FP has not been advocated as a mainstream monotherapy for AK and cutaneous malignancies, in part because "skip areas" of keratinocytic atypia would intuitively limit treatment efficacy. In order to test whether this is true, Katz and colleagues evaluated the efficacy of FP using a popular 1550-nm fractionated erbium-doped fiber laser to treat facial AK. This small pilot study was not blinded, had no controls, and included 14 men (59-79 years of age, Fitzpatrick Skin Phototypes I and II, mean facial AK count = 22.1) who received 5 laser treatments at 2- to 4-week intervals. Investigators assessed both clinical and histologic resolution of AK at 1 month, 3 months, and 6 months after the final laser treatment. The study design included a 1-month wash-out period for all AK treatments (eg, cryotherapy, topical chemotherapy, photodynamic therapy) and a 3-month wash-out period for topical retinoids and corticosteroids. Most FP treatments were performed at treatment level 11, 70 mJ, 8-10 passes, covering 32%-40% of facial surface area per treatment. Representative AK were biopsied from each patient prior to the first laser treatment and adjacent skin was biopsied at 3 months.
The key results of this study were as follows:
When compared with baseline, AK counts decreased by 73.1%, 66.2%, and 55.6% at the 1-month, 3-month, and 6-month follow-up visits, respectively.
Although post-treatment biopsies showed a reduction in cellular atypia, most samples still showed either residual AK or squamous cell carcinoma. Only 2 biopsies showed other findings (eg, seborrheic keratosis, spongiotic dermatitis).
Follow-up biopsies showed improvement in other measures of photodamage, including acanthosis and papillary dermal elastosis.
All patients and investigators rated clinical improvement in AK lesions as either "moderate" or "marked."
No major adverse events were reported. Patients experienced mild to moderate posttreatment erythema and edema, which resolved within 7 days.
Treatment pain scores ranged from 2 to 9 using the visual analog scale of 0 to 10, with 1 patient withdrawing after the first treatment due to pain despite pretreatment with a topical anesthetic and Zimmer cooling during the procedure.
Viewpoint
Although this study was small and lacked a control group, it still yielded an important conclusion: FP is a poor stand-alone treatment for facial AK. Not only did clinical response rates diminish over a 6-month follow-up period, but FP failed to clear the vast majority of AK histologically, even after 5 treatments at relatively aggressive settings. Furthermore, FP treatments did not prevent some AK from progressing to squamous cell carcinoma during the follow-up period. In contrast, FP didreduce clinical and histologic signs of chronic photodamage such as solar elastosis.
It should be noted that this study used only one type of laser and did not explore the efficacy of other fractional nonablative and ablative devices. Furthermore, Katz and colleagues correctly pointed out that FP may still have a role in the treatment of facial AK, perhaps as a means to enhance topical chemotherapy or photodynamic therapy by enhancing epidermal penetration. Future studies should continue to address this potential augmenting role.
Abstract
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