['Multiple primary upper aerodigestive tract carcinomas can occur in up to 15% of patients. We have shown previously that half of the patients with multiple upper aerodigestive tract squamous cell carcinomas are initially seen with synchronous tumors. Most metachronous squamous cell carcinomas become manifest within 3 years.', 'To examine the expression of 2 proteins-cyclin D1 and p53--in an attempt to predict the occurrence of multiple primary malignant neoplasms (MPs).', "Monoclonal antibodies to cyclin D1 (DCS-6 [dilution, 1:50]. Novocastra Laboratories Ltd, Newcastle, England) and p53 (DO-7 [dilution, 1-100], Dako Corp, Carpinteria, Calif) proteins were used. Resection specimens from a total of 47 patients, 12 patients with MP and 35 patients with nonmultiple primary malignant neoplasms, were analyzed. Those in the nonmultiple primary malignant neoplasm group had longer than 3 years' follow-up to ascertain the absence of MP.", 'Tumor overexpression of cyclin D1 was significantly associated with the development of MP (P<.01). Tumor overexpression of p53 was also frequent in patients with MP although statistical significance was not achieved. The combination of these 2 parameters was an even greater predictor of MP (P<.001).'] Does cyclin D1 and p53 overexpression predict multiple primary malignant neoplasms of the hypopharynx and esophagus?