FLEX October 2023

ORIGINAL ARTICLE

Relationship between CO 2 laser–induced artifact and glottic cancer surgical margins at variable power doses

Malcolm A. Buchanan, PhD, FRCS (ORL-HNS), 1 Hedley G. Coleman, FCPath (SA), FFOP (RCPA), 2,3 James Daley, BDent, 3 James Digges, BDent, 3 Mark Sandler, BDent, 3 Faruque Riffat, MS, FRACS, 1 Carsten E. Palme, FRACS 1 *

1 Department of Otolaryngology/Head and Neck Surgery, Westmead Hospital, University of Sydney, Westmead, New South Wales, Australia, 2 Department of Tissue Pathology and Diagnostic Oncology, Institute for Clinical Pathology and Medical Research, Pathology West, Westmead Hospital, University of Sydney, Sydney, Australia, 3 Faculty of Dentistry, University of Sydney, Westmead, New South Wales, Australia.

Accepted 13 April 2015 Published online 15 July 2015 in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/hed.24076

ABSTRACT: Background. The carbon dioxide laser can induce thermal cytologic artifacts at the margin of early glottic squamous cell carcinoma histologic specimens, which makes assessment of the margin difficult. This study assesses and correlates the depth of laser-induced thermal artifact with laser power rating. Methods. The surgical margins of 30 patients with early glottic squa mous cell carcinomas who underwent laser resection were reanalyzed retrospectively. Results. Thermal damage consisted of collagen denaturation within the vocal cord lamina propria and vocalis muscle, and epithelial structural changes. There was a decrease in depth of tissue artifact with increased INTRODUCTION Since 1972, transoral laser microsurgery (TLM) has become increasingly accepted worldwide as an optimum therapeutic modality for excision and ablation of laryn geal mucosal lesions, including early to moderately advanced squamous cell carcinomas. 1,2 Squamous cell carcinomas account for 95% of all laryngeal cancers, and arise most frequently in the glottis. 3 Five-year survival rates of 95% have been reported with TLM for early glot tic carcinomas, 4 with rates of 5-year disease-free survival at 87.9%, ultimate local control with laser alone 94.2%, disease-specific survival 99.0%, overall survival 92.2%, and organ preservation 96.2%. 5 Recurrence rates at 2 years postoperatively are low, and have been cited at 5% 6 and 11%. 7 The chief advantages of TLM over open surgi cal procedures or a course of external beam radiotherapy include lower surgical complexity with avoidance of tra cheostomy, shorter hospitalization, lower functional mor bidity in terms of deglutition and speech, lower cost, and the possibility of reserving re-treatment options (namely further laser surgery or radiotherapy, but also open sur gery) in case of local failure or second primary. 2,8,9 Fur

power rating ( p > .05). The average depth of thermal damage was 380.83 6 178.79 l m. Conclusion. The laser causes less thermal damage at higher power, pre sumably because of the increased speed of cutting and reduced contact time with surrounding cells. Knowledge of the depth of thermal artifact is important surgically when ensuring the cancer is excised with suffi cient oncologic margin. V C 2015 Wiley Periodicals, Inc. Head Neck 38 : E712–E716, 2016 KEY WORDS: CO 2 laser, histologic margin, thermal artifact, glottic cancer, power setting thermore, it has been shown on subjective quality of life self-evaluations that patients treated with TLM had signif icantly higher scores for questions relating to deglutition and xerostomia than irradiated patients. 10 There were no documented differences in subjective voice quality. How ever, in terms of objective voice comparisons, irradiated patients scored higher. Postoperative discomfort is also reported to be less when laser surgical methods are used. 11 In order to achieve local disease control and therefore ultimate cure, complete oncologic excision of the early glottic carcinoma with an adequate margin is paramount. It is well-established that patients with close or involved surgical margins have significantly higher rates of locore gional recurrence and potentially decreased survival. 4,12–14 Up to 75% of patients who have an involved surgical margin will have local recurrence or residual disease at the time of reoperation. 15 Recurrence of early-stage laryn geal cancer may be amenable to further repeated laser excisions, but if recurrence is multifocal or at the anterior commissure (where adequate anterior margins can be hard to achieve), 13 then more aggressive therapy, either a course of external-beam radiotherapy or total salvage lar yngectomy with an associated increase in morbidity and decreased cure rates, may be required. 2 The energy associated with the CO 2 laser beam is con verted into radiation, heat, photoacoustic, and mechanical forms, and undergoes absorption, reflection, scatter

* Corresponding author : C. E. Palme, Otolaryngology/Head and Neck Surgery, Westmead Hospital, University of Sydney, Westmead, New South Wales 2145, Australia. E-mail: carsten.palme@health.nsw.gov.au

E712

HEAD & NECK—DOI 10.1002/HED APRIL 2016