Regional differences in cervical cancer incidence and associated risk behaviors among Norwegian women: a population-based study.

Background Cervical cancer incidence is influenced by screening and risk factors in the population. The main risk factor for cervical cancer is sexually transmitted human papillomavirus (HPV), which is sexually transmitted and thus associated with sexual behavior. Smoking, parity and hormonal contraceptive use may also be associated with cervical cancer risk. We compared incidence, screening coverage and risk behaviors for cervical cancer between health regions in Norway. Methods We obtained data on incidence of cervical cancer among Norwegian women during 1992-2016 and data on screening coverage from the Cancer Registry of Norway. We obtained data on sexual behavior and smoking from a population-based survey of 16,575 Norwegian women who were 18-45 years old in 2005. Results Cervical cancer incidence was higher in the northern and southeastern region than in the middle and western region (range in incidence per 100,000 person-years during 1992-2016; north: 10.5 to 14.6; southeast: 9.3 to 12.9; mid: 6.8 to 9.5; west: 8.4 to 10.0). The incidence decreased modestly in the north (average annual percentage change (95% confidence interval) - 1.0 (- 1.2 to - 0.7)) and southeast (- 0.7 (- 1.0 to - 0.3)), but did not change significantly in the mid (- 0.3 (- 1.0 to 0.4)) and west (- 0.3 (- 0.6 to 0.0)). Compared to the national average, women in the north had earlier sexual debut, more partners and higher prevalence of ever having had a sexually transmitted infection (STI), while the opposite was observed among women in the west. Women in the middle and southeastern regions tended to be similar to the national average for sexual behaviors. Although less pronounced, the prevalence of smoking showed regional patterns similar to that observed for sexual behaviors, while ever-use of hormonal contraceptives and cervical screening coverage was similar between regions. Conclusions There were regional differences in cervical cancer incidence during the era of nationally organized cervical screening in Norway. To some extent, these differences corresponded to regional differences in risk behavior for cervical cancer in the Norwegian female population.