Anal Cancer Diagnosis and Mortality Rates On the Rise

A new analysis observed a significant increase in the incidence of and mortality associated with squamous cell carcinoma of the anus (SCCA).

“Squamous cell carcinoma of the anus (SCCA) incidence is rising in the United States (US),” the study authors posited. “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 this rise.”

The researchers gathered data from the US Cancer Statistics dataset on SCCA incidence trends spanning 2001 through 2015 and mortality spanning 2001 through 2016. Annual and average annual percentage change (AAPC) was determined with joinpoint regression, and incidence rate ratios (IRRs) and age-period-cohort modeling were employed to establish incidence patterns by five-year age group and birth cohort.

The authors observed significant increases in SCCA incidence, notably in specific groups.

“Given the historical perception that anal cancer is rare, it is often neglected,” said lead study author Ashish A. Deshmukh, PhD, MPH, an assistant professor at UTHealth School of Public Health, in a press release. “Our findings of the dramatic rise in incidence among black millennials and white women, rising rates of distant-stage disease, and increases in anal cancer mortality rates are very concerning.”

Each year, SCCA incidence rose 2.7% (95% CI, 2.1% to 3.3%); the increase was more significant among age groups 50 years and older. When stratified by sex, distant stage SCCA incidence for men tripled (AAPC, 8.6%; 95% CI, 5.4% to 12.0%), and for women increased by 7.5% (95% CI, 4.8% to 10.2%). Among both sexes, regional stage SCCA incidence almost doubled (AAPC, 4.7% for men and women). Localized stage AAPC for men was 1.3% (95% CI, 0.6% to 2.0%) and for women was 2.3% (95% CI, 1.8% to 2.8%).

Age-related incidence rates also differed between different races: “Compared to adults born circa 1946, recent born Black men (born circa 1986) had nearly fivefold higher (IRR, 4.7; 95% CI = 2.1-10.2) risk of SCCA and the risk doubled among White men (IRR= 2.0; 95% CI = 1.7-2.2) and White women (IRR, 2.1; 95% CI = 1.9-2.3) born after circa 1960.”

Mortality rates are also on the rise, increasing annually by 3.1% (95% CI, 2.6% to 3.5%); the increase was more pronounced in age groups 50 years and older. An annual increase was observed in incidence-based mortality of 1.9% (95% CI, 0.5% to 3.4%), with a significant annual increase in adults aged between 60 and 69 years (4.9%; 95% CI, 2.4% to 7.3%).

“Screening for anal cancer is not currently performed, except in certain high-risk groups, and the results of this study suggest that evaluation of broader screening efforts should be considered,” said study author Keith Sigel, MD, PhD, MPH, associate professor of medicine at Icahn School of Medicine at Mount Sinai, in a press release.