[Use of photodynamic laser therapy in gynecology]

Photodynamic therapy of vulvar intraepithelial neoplasia III using topically applied 5-aminolevulinic acid

OBJECTIVES

The aim of this study was twofold: first, to determine the feasibility of photodynamic therapy (PDT) of vulvar intraepithelial neoplasia III (VIN III) using topically applied 5-aminolevulinic acid (ALA) for photosensitization, and second, to compare PDT results with those of laser evaporation and local excision.

METHODS

Fifteen patients with VIN III had 10 g of 10% ALA gel applied to the entire vulva. Two to three hours after drug application the vulva was irradiated with 120 J/cm(2) laser light at a wavelength of 635 nm. The procedure was performed without anesthesia in most patients. Thirty patients with VIN III treated by laser evaporation and 27 patients treated by surgical excision served as controls.

RESULTS

Eight weeks following PDT, 11 of 15 patients were free of VIN III as determined by biopsy. Excellent tissue preservation was achieved and no ulcers or scarring occurred. Three recurrences were seen during follow-up, at 5, 6, and 7 months after PDT. Twelve months after treatment, analysis of disease-free survival revealed no statistically significant difference between patients treated with PDT and patients treated with conventional treatment modalities (P = 0.67) but the power of this analysis is low. In multivariate analysis, multifocal disease was the sole variable associated with a reduced disease-free survival.

CONCLUSION

While PDT of VIN III seems to show efficacy similar to that of conventional treatment modalities it offers unique advantages: healing time is short, preservation of normal vulvar appearance is excellent, and PDT may be performed without anesthesia. Hence, PDT of VIN III deserves further investigation.

Prevention of cervix cancer

Cervix carcinoma is an important health problem world-wide, being the second most common cancer among women, ranking first in many developing countries. A number of important epidemiological risk factors have been identified as contributing to the development of CIN and invasive cervix carcinoma. Of key importance is infection with human papillomavirus (HPV), which is the primary risk factor. There are evolving primary and secondary preventive strategies that could further reduce the burden from cervical carcinoma. The possible primary preventive strategies include risk reduction, diet or dietary supplements, HPV vaccines, and other chemopreventive agents. The possible advances in secondary preventive strategies include new technologies for Pap smears, HPV typing triage, and other adjuvant screening procedures. The impact of these strategies will depend upon evidence to support their use along with the characteristics of the population and environment in which they are used.

5-aminolevulinic acid-mediated photodynamic therapy of intraepithelial neoplasia and human papillomavirus of the uterine cervix--a new experimental approach

The aim of this study was to treat patients for ectocervical dysplasia [cervical intraepithelial neoplasia (CIN) grades 1 and 2] and associated human papilloma virus (HPV) infections with photodynamic therapy (PDT). In 20 patients, 5-aminolevulinic acid (5-ALA, 12% w/v) was applied topically with a cervical cap 8 h prior to illumination. A thermal light source (150 W halogen lamp) emitting a broadband red light (total energy: 100 J/cm2, fluence rate: 90 mW/cm2) was used for superficial illumination of the portio. In addition, an Nd:YAG pumped dye laser (652 nm) was used to illuminate the cervical canal (total energy: 50 J/cm2, fluence rate: 300 mW/cm2). Preliminary results of follow-ups at 1, 3, 6, and 9 months posttherapy showed a cytological improvement in the grading of the PAP smears in 19 patients and the eradication of cervical HPV in 80%. These results demonstrate that ectocervical dysplasia and associated HPV infections can be treated by PDT.

Systems for light application and dosimetry in photodynamic therapy

Successful photodynamic therapy requires homogeneous irradiation and light detection for dosimetry. Light delivery devices and detectors for treatment of spherical and cylindrical hollow organs have been developed. For photodynamic therapy of multifocal superficial bladder tumours a catheter with an isotropic emitter is centred by a balloon. Light which is backscattered from the tissue surface is used for on-line dosimetry. The irradiation and dosimetry concept has been proven by computer simulations for a non-spherical bladder shape. Larynx, bronchi, oesophagus and cervix have been irradiated by devices adapted to the shape of the organ. The light distribution is homogenized by multiple backscattering from a nearly white layer in contact with tissue, a promising method also for hollow organs with irregular geometry. The homogeneity of the light distribution as well as the dosimetry have been improved by the devices to be presented.