The clinical utility of the test refers to the likelihood that the test will, by prompting an intervention, result in an improved health outcome. The clinical utility of a genetic test is based on the health benefits related to the interventions offered to people with positive test results. Theoretically, there are at least five strategies that might improve the health outcome of people with a genetic susceptibility to cancer:
Correction of the underlying genetic defect (not currently available)...
The larynx is divided into the following three anatomical regions:
The supraglottic larynx includes the epiglottis, false vocal cords, ventricles, aryepiglottic folds, and arytenoids.
The glottis includes the true vocal cords and the anterior and posterior commissures.
The subglottic region begins about 1 cm below the true vocal cords and extends to the lower border of the cricoid cartilage or the first tracheal ring.
The supraglottic area is rich in lymphatic drainage. After penetrating the pre-epiglottic space and thyrohyoid membrane, lymphatic drainage is initially to the jugulodigastric and midjugular nodes. About 25% to 50% of patients present with involved lymph nodes. The precise figure depends on the T stage. The true vocal cords are devoid of lymphatics. As a result, vocal cord cancer confined to the true cords rarely, if ever, presents with involved lymph nodes. Extension above or below the cords may, however, lead to lymph node involvement. Primary subglottic cancers, which are quite rare, drain through the cricothyroid and cricotracheal membranes to the pretracheal, paratracheal, and inferior jugular nodes, and occasionally to mediastinal nodes.
A clear association has been made between smoking, excess alcohol ingestion, and the development of squamous cell cancers of the upper aerodigestive tract. For smokers, the risk of the development of laryngeal cancer decreases after the cessation of smoking but remains elevated even years later when compared to that of nonsmokers. If a patient who has had a single cancer continues to smoke and drink alcoholic beverages, the likelihood of a cure for the initial cancer, by any modality, is diminished, and the risk of second tumor is enhanced. Because of clinical problems related to smoking and alcohol use in this population, many patients succumb to intercurrent illness rather than to the primary cancer. (Refer to the PDQ summary on Smoking Cessation and Continued Risk in Cancer Patients for more information.)
Second primary tumors, often in the aerodigestive tract, have been reported in as many as 25% of patients whose initial lesion is controlled. A study has shown that daily treatment of these patients with moderate doses of isotretinoin (i.e., 13-cis-retinoic acid) for 1 year can significantly reduce the incidence of second tumors. No survival advantage has yet been demonstrated, however, in part because of recurrence and death from the primary malignancy.
Supraglottic cancers typically present with sore throat, painful swallowing, referred ear pain, change in voice quality, or enlarged neck nodes. Early vocal cord cancers are usually detected because of hoarseness. By the time they are detected, cancers arising in the subglottic area commonly involve the vocal cords; thus, symptoms usually relate to contiguous spread.