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ALA-PDT IN TREATMENT OF ANOGENITAL WARTS.

Anogenital warts (or condylomata acuminata) are a very common sexually transmitted disease characterized by superficial skin lesions in the anogenital area that is caused by human papillomavirus (HPV). The disease is not life-threatening but greatly affects the psychology and quality of life of the patient. There are many treatments for diseases such as CO2 laser, cryotherapy, imiquimod, etc. Photodynamics (ALA-PDT) is the treatment that selectively destroys lesions with high cleaning-lesion, low recurrent rates, is recommended for genital warts.

  1. Photodynamic therapy:

Photodynamic therapy (PDT) aims to destroy the desired target selectively thereby minimizing damage to normal tissue. The photodynamic reaction consists of the excitation of photosensitizers (porphyrins) by visible light in the presence of oxygen, resulting in the generation of reactive oxygen species, particularly singlet oxygen. These reactive oxygen species mediate cellular and vascular effects, depending on the tissue localization of the photosensitizer, and results in a direct or indirect cytotoxic effect on the target cells.

In dermatology, PDT has been used effectively for precancerous and malignant conditions such as actinic keratosis, BCC, Bowen disease, and superficial squamous cell carcinoma, as well as for inflammatory and infectious dermatoses such as localized scleroderma, acne vulgaris, and leishmaniasis.

 

Mechanism of action of photodynamic

A relatively new approach is the treatment of aging skin with PDT (photochemorejuvenation). The dose depends on the light source and the photosensitizer, as well as the disease that needs treatment.

Superficial BCC lesions after 3-hour incubation with mALA were illuminated by Wood light

 Genital warts in urethra before and after 1 week of treatment with ALA-PDT.

Contraindication:Porphyria

  • Pregnancy
  • Hypersensitive to systemic or topical photosensitizers.

ADR and complication of PDT:

  • Photohypersensitivity
  • Pain, warmth, burning, stinging, smarting and stabbing
  • Inflammation
  • Location: scar, postinflammatory, hyper/hypopigmentation.
  1. Clinical efficacy of the anogenital warts treatment by PDT

Comparative study of photodynamic therapy vs. CO2 laser vaporization in treatment of condylomata acuminata, a randomized clinical trial
Methods:

  • Sixty-five patients with CA were allocated into the treatment (ALA-PDT) group and treated with 20% ALA solution under occlusive dressing for 3 h followed by irradiation with the helium–neon laser at a dose of 100 J cm2 and a power of 100 mW.
  • Another 21 CA patients were allocated into the control group and treated with the CO2 laser. The treatment was to be repeated 1 week later if the lesion was not completely removed after the first treatment.

 

  The complete removal rate after 1 time The complete removal rate after 2 times Recurrence rate
ALA-PDT 95% 100% 6.3%
Laser CO2 100%   19.1%

 

The present study shows that topical application of ALA-PDT is a simpler, more effective and safer therapy with a lower recurrence for treatment of CA compared with conventional CO2 laser therapy.

The side-effects in patients treated with ALA-PDT mainly included mild burning and/or stinging restricted to the illuminated area.

 

Clinical Analysis of Five Methods Used to Treat Condylomata Acuminata

Method:

361 patients diagnosed with CA were divided into 3 groups according to the maximum diameter of their lesion:

Group A (<0.5 cm)

Group B (0.5–2.0 cm)

Group C (>2.0–4.0 cm)

Five treatments were compared in each group, and the clinical outcomes were evaluated during followups. The patients then received one of the following treatments: ALA-PDT, cryotherapy,

CO2 laser, ALA-PDT plus cryotherapy, and ALA-PDT retreatment (following cryotherapy or CO 2 laser treatment).

Note: Patients in the ALA-PDT plus cryotherapy group first underwent cryotherapy and then immediately began receiving a wet compression of 20% 5-ALA solution and PDT, weekly for 4 sessions. Conversely, patients in the ALA-PDT retreatment group were first treated with cryotherapy or CO 2 laser until lesion disappearance, and then were retreated with ALA-PDT therapy 4 times. The lesions were evaluated for recurrence at 4, 8, and 12 weeks after the last treatment.

Results:

Conclusion:

ALA-PDT is a safe and effective choice in the treatment of condyloma accuminata, besides others: cryotherapy, laser CO2.

The choice of treatment should be based on the size of the lesions.

  • ALA-PDT might be the first choice for the patients with a single CA lesion <0.5 cm in diameter
  • ALA-PDT plus cryotherapy could be better for the treatment of CA lesions 0.5–2.0 cm in diameter
  • ALA-PDT retreatment (wherein cryotherapy or CO2 laser treatment is first times) might be optimal for the treatment of a single wart >2.0–4.0 cm in diameter.

Reference

  1. Chen K., Chang B.Z., Ju M., et al. (2007). Comparative study of photodynamic therapy vs CO2 laser vaporization in treatment of condylomata acuminata: a randomized clinical trial. Br J Dermatol, 156(3), 516–520.
  2. Shi H., Zhang X., Ma C., et al. (2013). Clinical Analysis of Five Methods Used to Treat Condylomata Acuminata. Dermatology, 227(4), 338–345.
  3. Herbert Hönigsmann,Rolf-Markus Szeimies, & Robert Knobler. (2012). Photochemotherapy and Photodynamic Therapy. Fitzpatrick Dermatology in General Medicine. Eight edition.

Author: Dr Nguyễn Duy Nhâm

Publisher: Social Work Department