Recurrence Rates of Premalignant Lesions after CO2 Laser Vaporization
Abstract:Background: Use of the CO2-Laser (λ = 10.6 μm, continuous wave, defocussed) is an established procedure for treatment of premalignant lesions. Through employment of the sp-mode as well as scanners, thermal laser effects can be reduced but, on the other hand, a lesser degree of destruction of dysplastic cells could lead to an increased recurrence rate. The purpose of this study was to evaluate prospectively the recurrence rates resulting from different methods of CO2 laser vaporization.
Methods: From May 1995 to May, 2002, 56 patients with a total of 68 premalignant lesions of the oral mucosa were treated in a prospective clinical study. Twenty-eight lesions were vaporized with the defocussed CO2 laser (cw, 15 W, 5–15 s, mean output 2.12 Wcm–2). In a further 21 lesions, a scanner (Swiftlase) was additionally employed with all other parameters held constant (mean output 212.4 Wcm–2). In the remaining 19 lesions, vaporization was carried out in the sp-mode (pulse duration 80 μs, pulse energy 20 mJ, mean output 228 Wcm–2) in which, as above, a scanner was also used. Follow-up examinations were carried out according to a standard protocol. In May, 2002, the recurrence rate in the 3 groups was determined.
Results: Clinically, use of the scanner in sp-mode resulted in the most irregular tissue resection. This can be accounted for by the irregular paths of the laser beam and the pulsed delivery of the laser energy. The lowest recurrence rates were yielded by the defocussed cw-technique followed by the cw-scanner and the sp-mode.
Conclusions: These results indicate that for treatment of premalignant lesions of the oral mucosa, the best results can be achieved with the defocussed CO2 laser. The incurrence of a deep thermal effect enhances destruction of deeper-lying dysplastic cells. Apparently, other methods with lesser penetration of thermal effects (e. g. sp, scanner) do not reach the deeper-lying cells and, consequently, render higher rates of recurrence.
Document Type: Research Article
Affiliations: 1: Department of Oral and Maxillofacial Surgery, Klinikum rechts der Isar, Technical University, Munich, Germany 2: Department of Pathology and Pathologic Anatomy, Klinikum rechts der Isar, Technical University, Munich, Germany
Publication date: May 1, 2004