JMIR Publications

ABSTRACT

Background:

Melanoma currently ranks as the fifth leading cancer diagnosis and is projected to become the second most common cancer in the United States by 2040. Melanoma detected at earlier stages may be treated with less-risky and less-costly therapeutic options.

Objective:

This study aims to analyze temporal and spatial trends in melanoma incidence by stage at diagnosis (overall, early and late) in Texas from 2000 to 2018, focusing on demographic and geographic variations to identify high-risk populations and regions for targeted prevention efforts.

Methods:

We utilized melanoma incidence data from all 254 Texas counties from the Texas Cancer Registry (TCR) from 2000 to 2018, aggregated by county and year. Among these, 250 counties had reported melanoma cases during the period. Counties with no cases reported in a certain year were treated as having no cases. Melanoma cases were classified by SEER Summary Stage and stratified by four key covariates age, sex, race/ethnicity and stage at diagnosis. Incidence rates (IRs) were calculated per 100,000 population, and temporal trends were analyzed using joinpoint regression to determine average annual percentage changes (AAPC) with 95% confidence intervals for the whole time period (2000-2018), the most recent 10-year period 2009-2018) and the most recent 5-year (2014-2018) period. Heatmap visualizations were developed to assess temporal trends by patient age, year of diagnosis, stage at diagnosis, sex, and race/ethnicity. Spatial cluster analysis was conducted using Getis-Ord Gi* statistics to identify county-level geographic clusters of high and low melanoma incidence by stage at diagnosis.

Results:

A total of 82,462 melanoma cases were recorded, with 74.7% early stage, 11.3% late stage, and 14% unknown stage. Most cases were identified as males and non-Hispanic whites (NHW). Melanoma IRs increased from 2000 to 2018, particularly among older adults (60+ years: AAPC range = 1.20% - 1.84%; p-value < 0.05), males (AAPC = 1.59%; p-value < 0.05), and NHWs (AAPC of 3.24% for early stage and 2.38% for late stage; p-value < 0.05). Early-stage diagnoses increased while the rates of late-stage diagnoses remained stable for the overall population. The spatial analysis showed urban areas had higher early-stage detection rates (p-value = 0.06), whereas rural areas showed higher late-stage incidence (p-value =0.054), indicating possible geographic-based differences in access to dermatologic care.

Conclusions:

Melanoma incidence in Texas increased over the study time period, with the most-at-risk populations being NHWs, males, and individuals aged 50 and above. The stable rates of late-stage melanoma among minorities and rural populations highlight potential differences in access to diagnostic care. Future prevention efforts may benefit from increasing dermatologic care access in areas with higher rates of late stage at diagnosis melanoma.