Cervical cancer incidence has decreased by more than 50% in Sweden since late 1960s, when a cervical screening program was introduced. However, during the last decade the incidence plateaued and from 2014 a clear increase in incidence was observed. Using recently available data (June 2017) the objective of this study was to investigate time trends in cervical cancer incidence in Sweden during 2005-2015 by age, histology and geographical locality.
Age standardized incidence was calculated yearly and for three time periods (2006-2009, 2010-2013, 2014-2015) and the mean annual change in cervical cancer incidence during 2005-2015 was estimated in linear regression models.
The incidence was stable from 2006-2009 to 2010-2013 at around 9,5 per 100,000 women, while in 2014-2015 an increase by around 20% was seen to 11,5 per 100,000 women. The mean annual change in incidence during 2005-2015 was 1,7%. At ages below age 30 the mean annual change was 6.4% and at ages 30-44 the mean annual change was 3,8%. For older age classes (45-59, 60-74, 75+) no statistically significant change was observed. For squamous cell cervical cancer the pattern was the same with an ever stronger mean annual increase at ages below age 30 (8.6%), although in absolute terms this represents a fairly small change due to a low incidence at ages below 30. For adenocarcinoma there was a mean annual increase of 4% at ages 30-44, but not statistically significant change for any other age class. Overall increase in cervical cancer incidence was strongest in seven middle sized Swedish counties (mean annual changes 7-8%), while for the three largest cities (Stockholm, Gothenburg and Malmö) the incidence was stable over time.
The reason for the increase in incidence during this time period is not yet known, but may be related to the regional organization of the cervical screening program in Sweden and/or an increase in the underlying risk of cervical cancer.