Anal cancer rates have surged in the past 15 years, and the sexually transmitted human papillomavirus (HPV) may be to blame, a new study suggests.
"What was very shocking to us was that the rate and incidence of anal cancer has increased very fast," said lead researcher Ashish Deshmukh. He's an assistant professor in the department of health services research, management and policy at UTHealth School of Public Health, in Houston.
Overall, anal cancer rates and deaths are increasing nearly 3% per year, making it one of the fastest-rising cancers, he added.
Some groups are being hit harder than others.
Anal cancer cases and deaths from the disease have more than doubled for people in their 50s and 60s. And anal cancer rates among black men born after the mid-1980s has increased five times, compared with black men born in the mid-1940s, the researchers found.
Also, the diagnosis of late-stage anal cancer has increased 7% per year, which Deshmukh said is very troubling because survival rates, once the cancer has spread, are very low.
Conversely, if anal cancer is caught early, the five-year survival is close to 70%, he noted.
HPV is preventable with a vaccine. Ideally, the two doses of vaccine are given to boys and girls before the age of 15 or three doses if vaccination starts at ages 16 through 26.
However, 50% of Americans who are eligible are not vaccinated, which could lead to a wave of new infections and an increase in anal cancer rates in the coming decades.
Deshmukh said that HPV vaccine should not be called a vaccine to prevent a sexually transmitted disease, but a vaccine to prevent cancer.
Anal cancer is not on most people's radar, even though it caused the death of actress Farrah Fawcett in 2009. The illness has also been diagnosed in former "Desperate Housewives" star Marcia Cross, whose husband also developed throat cancer linked to HPV.
Anal cancer develops at the end of the gastrointestinal tract. It's not like colon or rectal cancer because of its location and because it involves different cells than those cancers.
For the study, Deshmukh and his colleagues used cancer registries to collect data on nearly 69,000 cases of anal cancer and more than 12,000 deaths from 2001 to 2016.
The findings were published Nov. 19 in the Journal of the National Cancer Institute.
Dr. Arun Swaminath is director of the Inflammatory Bowel Disease Program at Lenox Hill Hospital in New York City. He said that "it's clear that the incidence of anal cancers is increasing."
Those most at risk for anal cancer include gay and bisexual men, but also smokers, obese people and HPV-infected women, Swaminath said.
Deshmukh advised that those at high risk for anal cancer, especially gay and bisexual men, should be screened regularly.
Swaminath added that "the silver lining is that given that 90% of anal cancers are due to HPV, that there is a vaccine."
If most Americans were vaccinated, it would likely arrest the vast majority of new cases of anal cancer, he said.
"Given the vaccine has only been available for a decade, it will take time for us to see the curve of new cancer cases bending downward," Swaminath explained.
For more on anal cancer, head to the U.S. National Cancer Institute.