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Trends in Squamous Cell Carcinoma of the Anus Incidence and Mortality in the United States


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In a study reported in the Journal of Clinical Oncology, Damgacioglu et al found that squamous cell carcinoma of the anus incidence and mortality rates increased in men and women aged ≥ 50 years at diagnosis between 2001 to 2005 and 2014 to 2018, with increases concentrated in Midwestern and Southeastern states. On the state level, incidence was associated with prevalence of AIDS in men and prevalence of current smoking among women.

A stated by the investigators, “Squamous cell carcinoma of the anus incidence and mortality rates are rising in the United States. Understanding state-level incidence and mortality patterns and associations with smoking and AIDS prevalence (key risk factors) could help unravel disparities and provide etiologic clues.”

Study Details

The study used information from U.S. Cancer Statistics and National Center for Health Statistics data sets to estimate state-level incidence and mortality rates during 2001 to 2005 and 2014 to 2018. Data from the Behavioral Risk Factor Surveillance System were used to identify current smoking patterns, and data from the HIV Surveillance system were used to identify AIDS prevalence patterns.

Key Findings

Between 2001 to 2005 and 2014 to 2018, the incidence of squamous cell carcinoma of the anus per 100,000 population increased from 2.29 to 3.36 (rate ratio [RR] = 1.47, 95% confidence interval [CI] = 1.42–1.53) among men aged ≥ 50 years and from 3.88 to 6.30 (RR = 1.63, 95% CI = 1.58–1.67) among women aged ≥ 50 years. Proportions of cases in this age group increased from 66.1% to 82.7% in men and from 77.7% to 89.4% among women. Mortality rates per 100,000 population increased from 0.46 to 0.74 (RR = 1.62, 95% CI = 1.49–1.77) among men and from 0.65 to 1.02 (RR = 1.57, 95% CI = 1.47–1.67) among women.

In contrast, incidence and mortality rates declined or remained stable among men and women aged < 50 years at diagnosis across the study periods. In 2014 to 2018, incidence rates per 100,000 population were < .05 among both men and women, declining in men (RR = 0.87, 95% CI = 0.81–0.92) and remaining stable in women (RR = 0.96, 95% CI = 0.91–1.02).

At the state level, marked increases across the study periods in incidence (≥ 1.5-fold for men and ≥ 2-fold for women) and mortality (≥ 2-fold for both) among persons aged ≥ 50 years were largely concentrated in the Midwestern and Southeastern states; these states collectively contributed to > 50% of the national burden of incidence and mortality.

State-level squamous cell carcinoma of the anus incidence rates in 2014 to 2018 were correlated (ρ = 0.47, P < .001) with state-level AIDS prevalence patterns among men and with state-level current smoking prevalence (ρ = 0.49, P < .001) among women.

The investigators concluded, “During 2001 to 2005 to 2014 to 2018, squamous cell carcinoma of the anus incidence and mortality nearly doubled among men and women age ≥ 50 years living in Midwest and Southeast. State variation in AIDS and smoking patterns may explain variation in squamous cell carcinoma of the anus incidence. Improved and targeted prevention is needed to combat the rise in squamous cell carcinoma of the anus incidence and mitigate magnifying geographic disparities.”

Ashish A. Deshmukh, PhD, MPH, of the Department of Public Health Sciences, Hollings Cancer Center, Medical University of South Carolina, Charleston, is the corresponding author for the Journal of Clinical Oncology article.

Disclosure: The study was supported by grants from the National Cancer Institute. For full disclosures of the study authors, visit ascopubs.org.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
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