Multiple primary malignancies in the head and neck: a clinical review of 121 patients.

A total of 121 multiple primary malignancies (quadruple, n = 2; triple, n = 11; and double, n = 108) were treated at the Department of Otorhinolaryngology, Kitasato University Hospital between July 1972 and December 1998. Of the 108 patients with double primary malignancies, 18 had synchronous double primary malignancies (SDPM), which were defined as occurrence of the index tumor and second malignancy within 6 months of each other, and 90 had metachronous double primary malignancies (MDPM), which were defined as occurrence of the index tumor and the second malignancy separated by a period of > 7 months. MDPM was subdivided into MDPM-F (head and neck malignancy occurred as the first tumor; n = 55) and MDPM-S (head and neck malignancy occurred as the second tumor; n = 35). Of the 55 patients with MDPM-F, 27 (49.11%) of the second malignancies were found in the digestive tract, 12 in the stomach (21.8%), 8 in the esophagus (14.5%) and 7 in lower digestive tract tumors (12.7%). The 3- and 5-year survival rates of MDPM-F were 79.2% and 62.3%, respectively. Differential diagnosis between multiple primary malignancy (MPM) and multicentric tumors is often difficult when the lesions involve the oral cavity, pharynx and esophagus. We suggest that it is beneficial to follow patients for as long as possible in order to facilitate diagnosis of tumor recurrence, metastasis and MPM.