Photodynamic therapy: is it a valuable treatment option for actinic keratoses?

Actinic keratosis - review for clinical practice

Actinic keratosis (AK) is a lesion that arises as a result of excessive exposure to solar radiation and appearing predominantly on Fitzpatrick phototype I and II skin. Given that some AKs evolve into squamous cell carcinoma, these lesions are considered premalignant in nature, occurring mostly in elderly men and immunosuppressed individuals chronically exposed to ultraviolet (UV) radiation. There are several mechanisms for the formation of AKs; among them are oxidative stress, immunosuppression, inflammation, altered proliferation and dysregulation of cell growth, impaired apoptosis, mutagenesis, and human papillomavirus (HPV). Through the understanding of these mechanisms, several treatments have emerged. Among the options for AK treatment, the most commonly used include 5-fluorouracil (5-FU), cryotherapy, diclofenac, photodynamic therapy (PDT), imiquimod (IQ), retinoids, and ingenol mebutate (IM). There have been recent advances in the treatment options that have seen the emergent use of newer agents such as resiquimod, betulinic acid, piroxicam, and dobesilate. The combination between therapies has presented relevant results with intention to reduce duration of therapy and side effects. All AK cases must be treated because of their propensity to transform into malignancy and further complicate treatment. In addition to medical or surgical care, education about sun exposure prevention remains the best and most cost-effective method for AK prevention. The objective of this article is to conduct a literature review of the clinical presentation of AK including advances in treatment options available.

Solar keratoses: photodynamic therapy, cryotherapy, 5-fluorouracil, imiquimod, diclofenac, or what? Facts and controversies

Actinic keratosis is a common dermatologic condition that may regress, remain stable, or progress to squamous cell carcinoma. Some question whether all actinic keratoses should be routinely treated, whereas others contend that the unpredictable natural history of this disease necessitates treatment to prevent malignant transformation. Available treatments include photodynamic therapy, cryotherapy, 5-fluorouracil, imiquimod, and diclofenac. Each of these options has its advantages and disadvantages, although they all have a place in the management of actinic keratosis. An overview of these treatment modalities is presented, as are the controversies surrounding the treatment of actinic keratosis.

Understanding efficacy end-points in studies of field-directed therapy for actinic keratosis

BACKGROUND

The rates of short-term clearance of actinic keratoses appear to be comparable in clinical trials of topical treatments used in field therapy, but direct comparisons of efficacy results can be problematic. Trials use different efficacy end points, have different study designs, involve different anatomic sites, and enroll different patient populations. In addition, because adherence in real-world clinical practice differs from that observed in clinical trials, conclusions drawn from efficacy outcomes can be misleading. The objective of this review was to examine the efficacy end points used in studies of topical therapy for actinic keratosis, address other factors influencing efficacy outcomes in these studies, and discuss the possible influence of nonadherence on effectiveness.

METHODS

Review of the available literature on topical therapy for actinic keratosis.

RESULTS

The end points used to determine efficacy of therapies for actinic keratosis include a disparate group of outcomes, which can often make comparison between studies impossible.

CONCLUSIONS

Efficacy end points of clinical studies designed to assess the treatment of actinic keratosis should be standardized to facilitate between-trial comparisons, and studies should focus on the end points that are most clinically relevant.

Light Patch: Preliminary Report of a Novel Form of Blue Light Delivery for the Treatment of Actinic Keratosis

OBJECTIVE

To evaluate a novel light patch formulated for blue light delivery and topical activation of gamma-aminolevulinic acid (ALA) during photodynamic therapy for the treatment of actinic keratosis (AK).

MATERIALS AND METHODS

Ten volunteers with past unsuccessful treatment of AK were enrolled. Areas with AK lesions were treated with 20% ALA (Levulan) for an incubation period of 1 hour. Half of the area was treated with blue light patches (the patch emits 431 to 515 nm wavelength, 55.6 mJ/cm2 over 20 minutes), and the other half was left uncovered (control). The percentage of visible AK lesions cleared at the 3-month follow-up determined therapeutic efficacy.

RESULTS

The mean lesion count for all treatment areas was decreased from 7.60 to 2.40 (p<.01). The subjects had slight burning or itching and mild to moderate erythema. One subject developed a blister at the treatment site. Controls had clearance of 30%, 17%, and 20% for the face, scalp, and hands, respectively. Patients were satisfied with the results and noticed an improvement in skin texture.

CONCLUSION

Preliminary results show that the blue light patch is a potentially safe, effective, and alternative method for light delivery and topical ALA activation during photodynamic therapy of AK.

Photodynamic therapy for cosmetic applications

With the advent of short contact and pulsed light techniques, topical 5-aminolevulinic acid photodynamic therapy (5-ALA PDT) has become a viable clinical modality. Intense pulsed light, the pulsed dye laser, and blue light-emitting lamps have become the most commonly used devices in inducing a cosmetic PDT effect. More recently, by combining the photothermal effects of pulsed light with the photochemical effects of PDT, an enhanced cosmetic effect has been demonstrated in a variety of dermatologic conditions. In addition, the use of shorter 5-ALA incubation times allows for improved patient tolerance during treatment and subsequently fewer adverse effects in the postoperative period. A review of the current literature on cosmetic uses of PDT as well as our personal techniques are discussed in detail.

Photodynamische Therapie mit Methylaminooxopentanoat (MetvixR) und einer Breitbandlichtquelle (PhotoDyn 501): Praktische Erfahrungen bei Problem-Patienten mit Aktinischen Keratosen und Basalzellkarzinomen. Photodynamic therapy with methylaminooxopentanoate (MetvixR) and a broad band light source (PhotoDyn 501): Experiences in complicated patients with actinic keratoses and basal cell carcinomas

BACKGROUND

Actinic keratoses (AK) and basal cell carcinomas (BCC) may represent a therapeutic challenge because of special subtypes, location, previous therapy or accompanying diseases. Photodynamic therapy (PDT) offers a semi-conservative treatment option for selected indications.

PATIENTS AND METHODS

28 outpatients who had been admitted as complicated dermato-oncologic cases because of AK (n = 22) and BCC (n = 6) were treated with PDT, using methylaminooxopentanoate (MAOP, Methyl-Ala, Metvix) and a broad band light source (PhotoDyn 501). The treatment was evaluated for efficacy and subjective tolerance (local discomfort and pain).

RESULTS

A complete remission (CR) was achieved in 11/22 AK (50%) and 4/6 BCC (67%) cases. All three cases of a superficial BCC subtype underwent a CR. Among responders, tolerance was good in 12/15 cases (80%), as compared to 4/13 cases (31%) in non-responders. Focusing on 16/28 patients with good tolerance (57%), there was a CR in 12 cases (75% rate), whereas for the 12/28 patients with moderate to poor tolerance a CR was achieved in only 3 cases (25% rate). In a subgroup of 8 patients who, partly due to secondary diseases, were taking systemic retinoids or immunosuppressive-cytostatic medications, a CR was achieved in 3/8 cases (38%) with a good tolerance in only 1/8 cases (13%).

CONCLUSION

These observations confirm a good efficacy and tolerance of PDT in > or = 50% of a AK/BCC problem patient cohort. We found indications for 1) a positive correlation between efficacy and subjective tolerance as well as 2) the presumptive existence of a retinoid-dependent cutaneous PDT hyperalgesia. Effective pain control seems to be an essential cofactor for the success of PDT.

Topical methyl aminolevulinate

Methyl aminolevulinate (MAL), an ester of aminolevulinic acid, has been used effectively as a topical photosensitizing agent in the photodynamic therapy (PDT) of epidermal lesions such as actinic keratosis (AK) and basal cell carcinoma (BCC). The optimal regimen for MAL-PDT (as used in all clinical trials) is MAL 160 mg/g applied for 3 hours before illumination with red light (570-670 nm) at a total light dose of 75 J/cm(2), as determined in dose-finding trials. In randomized, multicenter, phase III clinical trials, treatment with MAL-PDT resulted in a complete response (i.e. complete disappearance) in up to 91% of AK lesions and up to 97% of BCC lesions. With regard to lesion response rates, MAL-PDT was superior to placebo-PDT (in AK or BCC), and at least as effective as cryotherapy (in AK or BCC) or excision surgery (in BCC). Cosmetic outcome with MAL-PDT was excellent to good in the vast majority of patients, and was judged by investigators to be better than with cryotherapy (in AK or BCC) or surgery (in BCC). black triangle Over 75% of BCC lesions treated with MAL-PDT, including difficult-to-treat BCC, were still in remission 12-24 months after the last treatment. MAL-PDT was generally well tolerated in clinical trials. The most frequently reported adverse events were local phototoxicity reactions, most of which were of mild to moderate intensity, resolved rapidly and were rarely treatment limiting.