FLEX October 2023

The Laryngoscope © 2023 The American Laryngological, Rhinological and Otological Society, Inc.

Outcomes of KTP Laser Ablation in Glottic Neoplasms: A Systematic Review and Meta-Analysis

Mustafa Suppah, MD ; Abdallah Kamal, MD; William E. Karle, MD; Rakan Saadoun, MD ; David G. Lott, MD

Objectives: To evaluate the safety and clinical effectiveness of transoral laser microsurgery (TLM) with potassium-titanyl phosphate (KTP) laser ablation for glottic neoplasms. Data Source: MEDLINE via PubMed, SCOPUS, Web of Science, and Cochrane Library. Review Methods: A systematic review and meta-analysis of studies assessing the safety and ef fi cacy of KTP laser therapy in patients with early-stage glottic neoplasms. Results: Eight studies were included. After an average follow-up of 3.3 years, the overall survival and disease-free sur vival for patients who underwent KTP were 90.7% (95% CI 85% – 96.5%) and 98.5% (95% CI 97.3% – 99.8%), respectively. In the single-arm meta-analysis, the pooled estimate of recurrence was 7.7% (95% CI 3.4% – 12%). The overall voice handicap index (VHI) estimate attributed to KTP in the single-arm meta-analysis was 6.76 (95% CI [3.05, 10.48]) and 5.21 (95% CI [2.86, 7.56]) within 6 months and after a one-year follow-up, respectively. Conclusion: KTP laser ablation is a safe and effective method for treating patients with early glottic neoplasms. KeyWords: Glottic cancer, potassium-titanyl-phosphate laser, recurrence, transoral laser microsurgery. Laryngoscope , 133:1806 – 1814, 2023

INTRODUCTION Laryngeal carcinoma is one of the most common cancers of the upper aerodigestive tract. The most prevalent subtype of laryngeal carcinoma is glottic carcinoma, 1 – 3 with squa mous cell carcinomas accounting for the majority of these cases. 4 However, there has been a gradual decline in laryn geal cancer incidence and mortality with the decreased use of tobacco products. 5 Radiation, transoral laser microsurgery, and open surgery may all be used to treat glottic carcinoma. 6 Prior studies have shown that oncologic outcomes are often favorable with either radiation therapy (RT) or transoral laser surgery (TLM). 7,8 Endoscopic therapy for early glottic cancer was fi rst described by Fraenkel in 1886, then by Lynch in 1920, before being further elabo rated by New and Dorton in 1941. 9 – 11 The development of the carbon dioxide (CO 2 ) laser with the surgical micro scope in the 1970s led to TLM with the CO 2 laser. With its good local control, few side effects, and ability to avoid RT or open laryngectomy for patients with persistent or From the Division of Laryngology, Department of Otolaryngology Head and Neck Surgery ( M . S ., W . E . K ., D . G . L .), Mayo Clinic Arizona, Phoenix, Arizona, USA; Hillman Cancer Center ( A . K .), University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA; and the Department of Plastic Surgery ( R . S .), University of Pittsburgh, Pittsburgh, Pennsylvania, USA. Additional supporting information may be found in the online version of this article. Editor ’ s Note: This Manuscript was accepted for publication on December 30, 2022 The authors have no funding, fi nancial relationships, or con fl icts of interest to disclose. Send correspondence to David G. Lott, MD, Mayo Clinic Arizona, 5777 East Mayo Boulevard, Phoenix, Arizona, 85054, USA. Email: lott.david@mayo.edu

recurring cancer, this has become a more attractive alter native to RT. 12 – 14 For early glottic neoplasms, studies comparing RT and CO 2 have shown comparable disease control rates (up to 95%) but have failed to consistently establish the oncological superiority of either modal ity. 15,16 CO 2 or RT for early glottic neoplasms has also not consistently shown advantages over one another in investigations comparing voice results. 17 – 19 CO 2 is often used to resect a glottic tumor en-bloc or via bread-loa fi ng. In 2003, a Japanese group applied TLM with the potassium-titanyl-phosphate (KTP) laser on 22 patients with early glottic carcinoma. 20 The technique of KTP ablation of early glottic cancer with ultra-narrow margins was fi rst proposed by Zeitels et al. in 2008 as a way to maximize post-operative glottal function. 21 The KTP laser ’ s 532-nm wavelength allows it to be preferentially absorbed by vascu lar tissue due to its af fi nity for oxyhemoglobin, a process known as selective photothermolysis. 22,23 This process differs from the CO 2 laser, which is selectively absorbed by water. As a result, this characteristic of the KTP laser theoretically enables more precise ablation of hypervascular malignant tissue with maximal preservation of the underlying, rela tively avascular, and lamina propria. Employment of the laser in a pulsed mode near the perimeter of the tumor helps maximize the preservation of neighboring healthy tissue. 21 The present systematic review and single-arm meta analysis aimed to assess the clinical outcomes and safety of KTP ablation in patients with early glottic neoplasms.

METHODS We followed the standards recommended by the Cochrane Collaborative Group to prepare the present systematic review

DOI: 10.1002/lary.30547

Laryngoscope 133: August 2023

Suppah et al.: KTP in Glottic Neoplasms

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