Risk and prognostic factors for multiple primary carcinomas in patients with head and neck cancer.

Background: Unexpected multiple primary carcinomas (MPCs) that develop in patients with head and neck carcinomas complicate approaches to their management. We therefore investigated the clinical factors associated with survival outcomes after the treatment of MPCs.
Methods: We performed a retrospective review of records of 1104 patients who underwent treatment for primary head and neck carcinoma at Hamamatsu University Hospital. We evaluated clinical staging, age, sex, smoking, alcohol consumption, the primary tumor site (particularly the involvement of the mucosal epithelial lining of the aerodigestive tract), and overall survival (OS) as determined by Kaplan-Meier analysis. Information on patients' survival status was obtained after a mean follow-up period of 43.8 months (range, 1-144 months).
Results: Among 566 patients with mucosa-associated carcinoma arising in the epithelial lining, the 5- and 10-year OS rates (68.49% and 58.96%, respectively) were significantly shorter than those of patients with mucosa non-associated carcinoma (74.22%, and 66.76%, respectively) (log-rank P = 0.0219). Older age (P = 0.016) and male sex (P < 0.001) were likely independent risk factors for developing MPCs; smoking (P < 0.001) and alcohol consumption (P < 0.001) were also significant risk factors.
Conclusion: Mucosa-associated carcinomas arising in the epithelial lining of the aerodigestive tract in the head and neck are a significant risk factor for developing MPC and are a poor prognostic factor. Careful follow-up and more frequent examinations of the aerodigestive tracts of these patients are recommended.
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