Recent Trends in Squamous Cell Carcinoma of the Anus Incidence and Mortality in the United States, 2001–2015

• Published in: JNCI : Journal of the National Cancer Institute Vol. 112; no. 8; pp. 829 - 838
• Main Authors: Deshmukh, Ashish A, Suk, Ryan, Shiels, Meredith S, Sonawane, Kalyani, Nyitray, Alan G, Liu, Yuxin, Gaisa, Michael M, Palefsky, Joel M, Sigel, Keith
• Format: Journal Article
• Language: English
• Published: United States Oxford University Press 01-08-2020; Oxford Publishing Limited (England)
• Subjects: Adult; Adults; African Americans - statistics & numerical data; Age; Age Factors; Aged; Aged, 80 and over; Anal cancer; Anus; Anus Neoplasms - epidemiology; Anus Neoplasms - mortality; Cancer; Carcinoma, Squamous Cell - epidemiology; Carcinoma, Squamous Cell - mortality; Colorectal cancer; Confidence intervals; Datasets as Topic; Disease control; Editor's Choice; Etiology; European Continental Ancestry Group - statistics & numerical data; Female; Hispanic Americans - statistics & numerical data; History, 21st Century; Humans; Incidence; Male; Men; Middle Aged; Mortality; Mortality - trends; SEER Program; Squamous cell carcinoma; Statistical analysis; Trends; United States - epidemiology; Women; United States; United States > US
• ISSN: 0027-8874; 1460-2105
• DOI: 10.1093/jnci/djz219

Abstract
Background
Squamous cell carcinoma of the anus (SCCA) incidence is rising in the United States. Study of incidence trends by stage at diagnosis, age-specific and birth cohort patterns, and trends in mortality could provide evidence for a true increase and etiological clues for the increase in incidence.
Methods
Using the US Cancer Statistics dataset, we examined trends in SCCA incidence (2001–2015) and mortality (2001–2016) rates. Join-point regression was used to compute annual and average annual percentage change (AAPC). Incidence patterns by 5-year age group and birth cohort were evaluated using incidence rate ratios (IRRs) and age-period-cohort modeling.
Results
SCCA incidence increased 2.7% per year (95% confidence interval [CI] = 2.1% to 3.3%), with pronounced increases in age groups 50 years and older. Distant-stage SCCA incidence tripled (AAPC = 8.6%, 95% CI = 5.4% to 12.0%, among men and AAPC = 7.5%, 95% CI = 4.8% to 10.2%, among women) and regional-stage SCCA incidence nearly doubled (AAPC = 4.7% for men and women) in both sexes; the AAPC for localized stage was 1.3% (95% CI = 0.6% to 2.0%) in men and 2.3% (95% CI = 1.8% to 2.8%) in women. Compared with adults born circa 1946, recently born black men (born circa 1986) had a nearly fivefold higher risk (IRR = 4.7, 95% CI = 2.1 to 10.2) of SCCA, and the risk doubled among white men (IRR = 2.0, 95% CI = 1.7 to 2.2) and white women (IRR = 2.1, 95% CI = 1.9 to 2.3) born after circa 1960. Anal cancer mortality rates increased 3.1% per year (95% CI = 2.6% to 3.5%) with statistically significant increases in age groups 50 years and older. SCCA incidence-based mortality increased 1.9% annually (95% CI = 0.5% to 3.4%), with a notable (4.9%, 95% CI = 2.4% to 7.3%, per year) rise in adults ages 60–69 years.
Conclusion
The increase in SCCA incidence, particularly advanced-stage disease, and a similar increase in mortality suggest a true increase in the occurrence of SCCA. Future research and improved prevention are urgently needed to mitigate the increasing disease burden.