Purpose: Invasive cervical cancer (ICC) rates have tremendously declined in the United States, yet new cases consistently occur in Maryland and throughout the United States. We hypothesized that although rates have generally declined, this decline is uneven across counties and over time.
Methods: Space-time cluster detection analysis was conducted to evaluate clusters of ICC incidence at the county level within Maryland between 2003 and 2012.
Results: The most likely cluster was a cluster of low incidence, which included 6 counties in eastern Maryland for the period 2009-2012. A secondary cluster of low rates, comprising 2 metropolitan counties in northern Maryland, was observed for the period 2009-2012. Two of the three clusters of high ICC rates occurred in 2009-2012 in the large metropolitan area of Baltimore City and another cluster in Frederick County, in rural western Maryland. The third cluster of high rates was observed 2005-2008, in western Maryland.
Conclusion: In recent periods, some Maryland counties have experienced anomalously high or low ICC incidence. Clusters of high incidence are not explained by differences in screening rates and may be due to failures in follow-up care for cervical abnormalities that need to be investigated. Clusters of low incidence may represent areas of successful ICC control.
Keywords: Cancer surveillance; Cervical cancer; SaTScan; Space–time cluster detection; Spatial epidemiology.