The inferior boundary is the trachea. Tumors of the subglottis often extend extralaryngeally because of proximity and access to the cricothyroid membrane. This preoperative test may serve as an important baseline, which can be helpful postoperatively in patients who have difficulty with the decrease in CO 2 that often ensues after laryngectomy. Invasion of paraglottic and preepiglottic spaces or extralaryngeal spread may be evident on CT scan and may preclude conservation surgery. Chest x-ray is necessary to rule out pulmonary metastases or second primary lung cancer.
Lung carcinoma is the most common second primary tumor in patients with laryngeal carcinoma.
Direct laryngoscopy Direct laryngoscopy under general anesthesia is necessary to rule out metachronous primary cancer, to obtain a biopsy, and to identify tumor boundaries. Verrucous cancer usually is treated surgically because it is believed to have a potential for degenerating to a more aggressive carcinoma when treated with radiation. If treated with sufficiently high doses of radiation, these hybrid tumors can be controlled successfully. Basaloid squamous and adenosquamous carcinoma are very rare and are high-grade aggressive neoplasms. Rare tumors, such as small-cell carcinoma, sarcomas, and adenoid cystic carcinoma, are treated with surgery and radiation.