Background: Cancer incidence raises progressively during life span; it is estimated that by the year 2030 almost 70% of all neoplasms will occur in people over 65 years old. As carcinogenesis is a multistep, time-requiring process, it is expected that as people live longer they are more likely to develop cancer, and therefore, the prevalence of multiple primary malignancies (MPM) is destined to increase with age.
Patients and methods: Records of all consecutive cancer patients referred to our center from January 2004 to January 2007 were reviewed. We chose the definition of MPM proposed by Warren and Gates. Multiple malignancies were assessed for elderly (>or=70 years old) and younger patients. t-Test and Mc Nemar test were used; subgroup analysis was also performed according to age stratification.
Results: A total of 1,503 consecutive patients were considered; 566 were 70 years old or more (mean age 76.5 years, range 70-96 years) and 878 were younger (mean age 57 years, range 18-69 years). The prevalence of multiple malignancies in the elderly people versus younger ones was 15% and 6%, respectively (P = 0.001). As far as the elderly population is concerned, 21% (56/271) of males compared with 14% (42/295) of females had developed MPM; no significant difference was found between the subgroups with MPM or not as far as age (P = 0.16), comorbidities (P = 0.79), medications (P = 0.76), CIRS-G score and index (P = 0.47, P = 0.54), and PS (P = 0.93) are concerned. Most frequent associations among cancer types were prostate with lung (10/87, 11%), prostate with colorectal cancer (10/87, 11%), and smoking-related cancer, namely lung and head and neck cancer (X/Y, 6%).
Conclusions: Elderly patients are more likely to develop MPM compared to younger ones. Significant cancer association according to field cancerogenesis concept was the one of smoking-related cancer; other MPM patterns were apparently a random phenomenon.