ABSTRACT
The extent to which the geographic diversity of the U.S. plays a significant role in melanoma incidence and mortality over time has not been precisely characterized. We obtained age-adjusted melanoma data for the 50 states between the years 2001-2019 from the SEER registry and performed hierarchical clustering (complete linkage, Euclidean space) to uncover geotemporal trend groups over 2 decades. While there was a global increase in incidence during this time (b1=+0.41, p<0.0001), there were 6 distinct clusters (by absolute and Z-score) with significantly different temporal trends (ANCOVA p<0.0001). Cluster 2 (C2) states had the sharpest increase in incidence with b1=+0.66, p<0.0001. For mortality, the global rate decreased (b1=-0.03, p=.0003) with 3 and 6 clusters by absolute and Z scores, respectively (ANCOVA p<0.05). Cluster 1 (C1) states exhibited the smallest decline in mortality (b1=-0.017, p=0.008). Mortality to incidence ratios (MIRs) declined (b1=-0.0037, p<0.0001) and harbored 4 and 6 clusters by absolute and Z-score analysis, respectively (ANCOVA p<0.0001). Cluster 4 (C4) states had the lowest rate of MIR decline (b1=-0.003, p<0.0001). These results provide an unprecedented higher dimensional view of melanoma behavior over space and time. With more refined analyses, geospatial studies can uncover local trends which can inform public health agencies to more properly allocate resources.
