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[Multiple primary cancers in patients with head and neck cancer and history of tobacco smoking and drinking].

In a total of 2083 cases of hollow organ cancer of the head and neck region treated in our institute in the past 20 years, the relative risk of second primary cancers was statistically studied by the person-year approach. The organ association in multiple primary cancers and the relationship between tobacco and alcohol consumption and the development of second primary cancers were also reviewed. The incidence of second primary cancers was significantly (p < 0.05) higher in patients having a lesion at the tongue (n = 502), mesopharynx (n = 188), hypopharynx (n = 224) and larynx (n = 621) and in the oral cavity (n = 203) than in the general population. With regard to organ association in multiple primary cancers, cancers in the oral cavity, esophagus and at the pharynx were found to occur as second primary cancers of the tongue, oral cavity, meso-hypopharynx and larynx at significantly high rates in males. Male laryngeal cancer was related to the lung. No relation of female lingual cancer to the esophagus was noted. The incidence of second primary cancer was very high in persons who had been heavy smokers and/or heavy drinkers before the occurrence of their primary cancer in the head and neck region. In these people, second primary cancers were found to occur at high rates as cancers related to tobacco smoking and drinking. Otherwise, in cases with head and neck cancers less related to tobacco smoking and drinking, the incidence of second primary cancers was low. From the above results, tobacco smoking and drinking may be closely related to a high incidence of second primary cancer following the first primary cancer in the head and neck region.