Unfavorable trends in incidence, mortality of squamous-cell anal cancer

Last Updated: 2019-12-25

By Will Boggs MD

NEW YORK (Reuters Health) - The incidence and mortality of squamous-cell carcinoma of the anus (SCCA) increased significantly in the early years of the 21st century, according to U.S. data.

SCCA is the most common histologic subtype of anal cancer, and more than 90% of cases are associated with human papillomavirus (HPV) infection.

Previous studies show the incidence of SCCA more than doubled between the late 1970s and early 2010s in the United States, while the incidence of adenocarcinoma, the second most common subtype, declined.

Dr. Ashish A. Deshmukh from UTHealth School of Public Health, in Houston, Texas, and colleagues analyzed a U.S. Cancer Statistics data set from the Centers for Disease Control and Prevention (CDC) National Program of Cancer Registries and the National Cancer Institute Surveillance, Epidemiology, and End Results (SEER) Program on cases of SCCA diagnosed from 2001 through 2015.

During this interval, the overall incidence of SCCA increased 2.7% annually, including 2.2% annual increases among men and 3.1% annual increases among women, the researchers report in the Journal of the National Cancer Institute.

The annual increase was higher among black men (2.8%) than white men (2.3%), but higher among white women (3.7%) than black women (2.6%).

The incidence of SCCA increased significantly for all age groups 50 years and older. In contrast, SCCA incidence rates decreased 2.9% annually among men (but not among women) under 40 years.

In the 40-49 year age group, SCCA incidence increased significantly during 2001-2009, followed by a decline in later years.

From 2001 through 2015, anal-cancer mortality rates increased 3.1% annually, with annual increases of 3.4% among men and 2.9% among women.

Mortality rates increased significantly for all racial/ethnic groups except "others" and for all age groups 50 years and older.

"SCCA is preventable through HPV vaccination; however, vaccination coverage (50% in 2017) remains suboptimal in the US and less than 30% of vaccine-eligible individuals or their family members received recommendation for HPV vaccination from their health care professionals," the authors note.

"Our findings call for future studies to identify reasons for the increase in SCCA incidence and mortality," they conclude. "Improved prevention strategies are urgently needed to mitigate the rising SCCA burden among a rapidly growing number of aging US adults."

Dr. James Yu of Yale School of Medicine's Cancer Outcomes, Public Policy, and Effectiveness Research Center, in New Haven, Connecticut, recently reported changing patterns of anal carcinoma in the U.S. He told Reuters Health by email, "We found that (anal) carcinoma in situ rates are actually going down - perhaps a precursor to declines in invasive SCCA in more recent years and the future."

"It is critical that the lay public understands: vaccination can prevent cancer," he said. "Hopefully, we are seeing the peak years of anal cancer, and that with vaccination these trends will reverse."

Dr. Deshmukh did not respond to a request for comments.

SOURCE: https://bit.ly/2qMNg7z Journal of the National Cancer Institute, online November 19, 2019.