Outcomes of larger glottic cancer volumes treated with radiotherapy
Reviewed by Karthika Shanthakunalan

T3 glottic cancer is characterised as vocal cord fixation and/or invasion into pre-epiglottic, post-cricoid, paraglottic spaces and/or within the inner cortex of thyroid cartilage. Traditionally, laryngectomy was considered the primary option to treat T3 laryngeal glottic cancers until other options became available aiming to preserve laryngeal function. These included chemotherapy, radiotherapy and transoral laser microsurgery. The paper seeks to investigate whether the debated management of higher primary volumes of T3 glottic tumours that have been treated with radiotherapy, are associated with worse oncologic outcomes. This was a multi-institutional Canadian, retrospective cohort study that included adult patients diagnosed with biopsy-proven glottic squamous cell carcinoma staged T3 N0-3, who underwent non-surgical curative intent with either intensity-modulated radiotherapy (IMRT) or volumetric-modulated arch radiotherapy (VMRT) with or without systemic therapy. A total of 319 patients were included with their tumour volumes measured with standardised CT imaging by expert head and neck radiologists. The two primary outcomes measured were overall survival (OS) and disease-free survival (DFS) calculated from radiotherapy to an end point (recurrence, death or last follow-up). Results showed each 1cm3 increase in volume was associated with statistically significant reduction in both OS and DFS, specifically, Hazard ratio (HR) of 1.07 and 1.04 respectively, thus indicating adverse outcomes with large volume tumours. Furthermore, those who received systemic therapy demonstrated improved DFS (HR 0.63, 95% CI 0.53-0.76). This was the largest study on this topic, and the authors quite correctly recognised the appropriateness of not putting a tumour volume cutoff to permit for surgical management. Similar to the UK’s current guidelines, they concluded the need for individualised multidisciplinary combined modality approach for patients with larger tumours with upfront laryngectomy, followed by postoperative radiotherapy and the offer of concurrent systemic therapy. Unfortunately, not all variables were evaluated, such as radiotherapy volumes and pre-treatment tracheostomy and hence, future work involving these factors would strengthen the study.

Association of Primary Tumor Volume with Survival in Patients with T3 Glottic Cancer Treated with Radiotherapy. A Study of the Canadian Head & Neck Collaborative Research Initiative.
Malik NH, Fu R, Hainc N, et al.
JAMA OTOLARYNGOL HEAD NECK SURG
2023;149(2):103-103-9.