Multiple primary cancer incidence in Italy

Data collected from eleven Italian population-based cancer registries (over all population 7 200 000 inhabitants) were used to compute the incidence of second independent cancers (MP) in a cohort of cancer patients aged 15 yea rs or more. Overall, 240 111 patients have been followed for 544 438 person -years during which 8766 second primary cancers were diagnosed leading to a n observed to expected ratio (SIR) of MP of 1.08 (95% Confidence Interval ( CI): 1.05-1.12). Restricting the analysis to metachronous cancers, there we re 6974 second primary cancers diagnosed among 198 303 patients during 508, 648 person-years with an SIR of 0.93 (95% CI: 0.90-0.96). According to the time since first cancer diagnosis, the SIR was significantly higher than ex pected during the first 2 months, then the overall risk was slightly lower than 1 up to 10 years after diagnosis. No differences were observed accordi ng to gender. The SIR significantly differed among the age groups with cons istent excess risks in subjects younger than 65 years in comparison with ol der ones. Overall, significantly elevated SIR for metachronous cancers were evidenced for oral cavity and pharynx, larynx, connective, skin non-melano ma, ovary and kidney cancers. For each cancer site, the site-specific risk of further MP has been evaluated. The identification of strong site-specifi c associations may be useful for clinicians when following-up patients. (C) 2001 Elsevier Science Ltd. All rights reserved.