Multiple primary tumours in patients with oral squamous cell carcinoma.

A series of patients with oral squamous cell carcinoma (SCC) observed at the "Regina Elena" Cancer Institute was retrospectively reviewed in order to analyse the risk factors for multiple and second primary tumours (SPTs), their impact on survival and effective measures to control this phenomenon. In a survey of 200 individuals with a median follow-up of 3.2 years (25th percentile: 1.2, 75th percentile: 5.5), the incidence rate of SPTs was 14%: 39% arose in the oral cavity, 18% in the oropharynx, 10% in the lung and 7% both in the lip and larynx. There were no cases of secondary oesophageal tumours. Ninety-six per cent of the diagnosed histological types of SPTs were SCCs. Forty per cent of the new cancers were synchronous and 60% were metachronous, developing at a steady rate of 1.5% per year with no evidence of plateau. The overall incidence, adjusted by the length of follow-up, was 40 SPTs per 1000 person-years of follow-up. Although all the patients were at a greater risk for SPTs, the rates widely varied, according to specific factors: heavy tobacco consumption accounted for a statistically significant risk excess which was particularly high among younger smokers with an index tumour of the lower oral cavity. No difference was noticed in relation to the index neoplasm stage. In patients both with localised and advanced index tumours, 5-year survival rates were lower in those with SPTs and the difference was statistically significant for the 2-year survivors who were most likely to overcome the first disease. The present study confirms, the exceptionally high incidence of multifocal SCC in oral cancer patients and emphasizes the importance of preventive measures, since careful screening procedures, carried out to detect multifocal tumours at an early stage, should improve survival in these patients.