CO₂ Laser Cordectomy Versus KTP Laser Tumor Ablation for Early Glottic Cancer: A Randomized Controlled Trial

CO₂ laser cordectomy has been the workhorse of laser surgery for early glottic squamous cell carcinoma (GSCC) since the early 1970s. During the last decades, potassium titanyl phosphate (KTP) laser surgery for early GSCC gained popularity, introducing the tumor ablation technique. Yet, there are no previous randomized controlled trials (RCT) that compare the oncologic and functional outcomes of KTP Laser ablation versus CO₂ laser cordectomy for early GSCC. This study aims to compare by means of an RCT, CO₂ laser cordectomy with KTP laser ablation for early GSCC, in terms of cure rates and vocal function.

A RCT conducted between 2013 and 2017. Patients with early GSCC were enrolled, and randomly assigned for either CO₂ cordectomy or KTP-ablation surgery with curative intent. All CO₂ cordectomies and most KTP-ablation procedures were performed under general anesthesia. Some KTP cases with residual disease were treated also under local anesthesia. Videostroboscopy measures, voice handicap index (VHI), GRBAS (a hoarseness scale for Grade, Roughness, Breathiness, Asthenia and Strain) score, and acoustic analyses were performed pre-operatively, 6 months and 3 years after surgery.

Twenty-four patients, 12 in each group, were enrolled. Nine in each group had T1a carcinoma, the remaining had either carcinoma in situ or T1b. The average number of procedures was 1.67( ± 0.89) and 1.33( ± 0.89) for the KTP and CO₂ groups, respectively. Although the tumor depth was comparable in both groups, patients in the KTP-ablation group underwent more superficial surgeries. Eleven (91.7%) procedures in the KTP group spared the vocal ligament, compared with 5 (41.7%) in the CO₂ group, (P = 0.023). All patients were alive and disease-free after four years. On post-operative videostroboscopy, normal mucosal waves appeared in 5 (42%) of the KTP patients versus none (0%) of the CO₂ (P = 0.02). The median post-operative non-vibrating portion was smaller in the KTP group (10%) compared with CO₂ (50%), P = 0.043. Nevertheless, GRBAS and VHI scores improved comparably in both groups.

KTP ablation technique offers similar curative outcome as CO₂ cordectomy but may allow for better preservation of vocal fold's architecture and function. Yet, the clinical significance of these findings is unclear, since the subjective measures improved comparably for these two treatment modalities. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.