Stage-specific incidence trends of melanoma in an English region, 1996-2015: longitudinal analyses of population-based data.

Annie Herbert,Georgios Lyratzopoulos,Nick J Levell,Minjoung M Koo,Matthew E Barclay,Gary A Abel,David C Greenberg

doi:10.1097/cmr.0000000000000489

Abstract

The aim of this study was to examine temporal trends in overall and stage-specific incidence of melanoma. Using population-based data on patients diagnosed with melanoma in East Anglia, England, 1996-2015, we estimated age-standardized time trends in annual incidence rates for each stage at diagnosis. Negative binomial regression was used to model trends over time adjusted for sex, age group and deprivation, and to subsequently examine variation in stage-specific trends by sex and age group. The age-standardized incidence increased from 14 to 29 cases/100 000 persons (i.e. 4% annually). Increasing incidence was apparent across all stages but was steepest for stage I [adjusted annual increase: 5%, 95% confidence interval (CI): 5-6%, and more gradual for stage II-IV disease (stage II: 3%, 95% CI: 2-4%; stage III/IV: 2%, 95% CI: 1-3%)]. Stage II-IV increase was apparent in men across age groups and in women aged 50 years or older. Increases in incidence were steeper in those aged 70 years or older, and in men. The findings suggest that both a genuine increase in the incidence of consequential illness and a degree of overdiagnosis may be responsible for the observed increasing incidence trends in melanoma in our population during the study period. They also suggest the potentially lower effectiveness of public health awareness campaigns in men and older people.

Highlights

Analyses of stage-specific time-trends of melanoma incidence could help to provide insights into mechanisms underlying increasing incidence: genuine increases in ultraviolet radiation exposure could be assumed to result in increasing incidence of each stage while overdiagnosis may lead to disproportionately greater increase in early stage disease
We explored whether stage-specific incidence trends varied by patient group, by investigating whether including three- and four-way interaction terms between the two demographic variables and the stage*year interaction improved the fit of the original negative binomial
There were 9,890 cases of melanoma diagnosed in East Anglia during 1996–2015 in an approximate population of 2.5 million during the study period

Summary

Introduction

The incidence of melanoma has increased dramatically in countries with predominantly Caucasian populations in recent decades and is projected to continue to increase for several countries.[1,2,3,4]. Analyses of stage-specific time-trends of melanoma incidence could help to provide insights into mechanisms underlying increasing incidence: genuine increases in ultraviolet radiation exposure could be assumed to result in increasing incidence of each stage while overdiagnosis may lead to disproportionately greater increase in early stage disease. Levell et al reported increasing incidence trends for stage I-III melanoma in 1991-2004, with a steeper increase of stage I disease.[13] it is important to examine more recent patient cohorts, and potential differences in stage-specific variation over time by sociodemographic group.[15]

Methods

Results

Conclusion