There was no statistically significant relationship between the expression of p16 and the age of patients, cigarette smoking, tumor location, tumor staging according to the Krouse and Cannady classification, the presence of dysplasia or the occurrence of relapse.

Endoscopic procedures are an effective method of IP treatment, however reasonable indications and surgeon experience should be taken into consideration.

In recent years, the incidence of sinonasal inverted papilloma (IP) in a stable population has increased significantly. The aim of the study was to analyze the occurrence of IP between the years 2002-2012 in relation to epidemiological factors in an unalterable area. Moreover, we wanted to start a discussion about the difficulties in determining the inci¬dence of benign lesions that are not included in registers. This retrospective study included a group of 69 patients who were treated in the Department of Otolaryngology, ENT Oncology, Poznań University of Medical Sciences. In 2006, we noticed a sudden change in referrals. We compared two groups of patients who were referred during two differ¬ent time periods: 11 patients (2002-2006) and 58 patients (2007-2012). Despite a marked difference in the number of patients, there were no differences between the groups in tumor location (p>0.05), stage (p=0.16), duration of symp¬toms (p=0.39), place of residence, and smoking (p=0.41). The patient`s age was the only variable that differed significantly between the groups (48.45 vs. 56.93 years; p=0.043569, respectively).