A retrospective observational study to assess the accuracy of preoperative computed tomography scan for thyroid cartilage involvement and T-categorization in patients with carcinoma larynx undergoing total laryngectomy

Background: Treatment for carcinoma larynx is dependent on the T-category, with T4a disease (major thyroid cartilage involvement and extra-laryngeal extension) requiring radical surgery while lesser stages are treated with voice conserving treatments including radiation or chemoradiation. Pre-treatment computerized tomography (CT) scan is routinely used to categorize the T-category; however, studies have reported variable accuracy. Objective: We aimed to ascertain the accuracy of the preoperative CT scan in determining major thyroid cartilage involvement and T-category of the tumor when compared to the postoperative histopathology report. Materials and Methods: This retrospective observational study was conducted between January 01, 2017, and May 31, 2021, in the Department of Radiodiagnosis at the Homi Bhabha Cancer Hospital, Sangrur, Punjab (India). We analyzed the data of 30 patients with histologically proven squamous cell carcinoma of the larynx, who had undergone preoperative CT scans followed by total laryngectomy. The diagnostic accuracy of the T-category based on the preoperative CT, including major thyroid cartilage involvement, extra-laryngeal extension along with other laryngeal subsites was compared to the postoperative histopathology report. Results: CT scan was highly precise in determining the preoperative T-category with an accuracy of 90%. Detection of erosion of the outer cortex of the thyroid cartilage had a sensitivity of 94.4% (95% CI, 74.2-99) for major thyroid cartilage involvement. When erosion of the outer cortex of the thyroid cartilage was combined with the soft tissue on both sides of the thyroid cartilage, the CT scan yielded an accuracy of 100% (95% CI, 88.65-100). CT showed a sensitivity of 92.9% (95% CI, 68.5-98.7) and a specificity of 87.5% (95% CI, 63.9-96.5) for extra-laryngeal extension. Conclusion: CT scan is an accurate and reliable preoperative investigation for diagnosing major thyroid cartilage involvement and T-category staging in patients with carcinoma larynx.