Multiple primary malignancies of the upper aerodigestive system.

Multiple primary carcinomas were found in 11.5% of 1,518 patients presenting with an index tumor in the oral, pharyngeal or laryngeal areas. These additional malignancies were subdivided into two groups: 1) those occurring in distant or unrelated tissues and 2) those occurring in a multicentric zone defined as including the oral area, pharyngeal area, larynx, esophagus and tracheobronchial tree. Although some trends were noted, a primary lesion may be found anywhere in the zone of multicentricity. The dynamic nature of the progressive transition of the potentially malignant tissues in the multicentric zone is reemphasized. The physician, treating patients with head and neck cancer, should be prepared not only to cope with simultaneously occurring primary cancers but also to be constantly vigilant for the later development of subsequent primary carcinomas.