Anal cancer may be on the rise in the U.S

 The number of people in the U.S. with anal cancer has tripled since the 1970s, according to a new study suggesting that rates of detection in high-risk groups may partly explain the increase in cases.
A U.S. cancer database search found that the rate of anal cancers of about one person per 100,000 between 1973 and 1996 three people per 100,000 between 1997 and 2009.

"I think the literature already showed that there is an increase in anal cancer cases, but we were surprised to see how dramatically increased," Dr. Lily Lai, the study's senior author of City of Hope in Duarte, California.

According to the American Cancer Society (ACS), approximately 7,000 people are diagnosed with anal cancer in the U.S. in 2013, and about 900 will die of the disease. By far the most common type of anal cancer is squamous cell carcinoma, which account for about 85 percent of the cases.

For the new study, Lai and her colleagues analyzed trends in the 11,231 squamous cell carcinoma cases described in a U.S. database for the years 1973 through 2009.

They had a big jump in the 23 years before that in 1997, 4224 people were diagnosed, compared with 7007 people in the 13 years thereafter.

Although both sexes showed an increase in the anal cancers, the rate for men jumped most dramatically - one in every 100,000 to three in every 100,000 men. Compared to the women's rate, which rose from 1.4 in every 100,000 women in every 100,000 to about 2.4.

Lai Reuters Health said that the big increase in cases among men was a novel finding, and her team suspect it may be due to more people to be screened more often, especially people with human immunodeficiency virus (HIV).
According to the team's report in the Journal of Clinical Oncology, a majority of people with HIV also persistent human papillomavirus (HPV) infections. The sexually transmitted virus is slightly less widespread in HIV-negative people, whose immune systems may eventually clear HPV infections of the body.

HPV is linked to the development of cervical cancer and anal cancer. The ACS says eight of every 10 anal in squamous cell carcinomas are caused by HPV.

"It may be that there is an increase in people (anal cancer) and that there are other factors involved that we do not know," Lai told Reuters Health. "We think it's probably a detection bias, which is the simplest explanation."

Dr. Robert Cima, a surgeon in the department of colon and rectal surgery at the Mayo Clinic in Rochester, Minnesota, said that could also mean that the number of in squamous cell carcinomas has not changed much in people without HIV or compromised immune systems.
"It shows, but definitely a patient without risk factors are at very low risk for developing this type of cancer, and a blanket screening program for all patients across the country would be a useful approach," said Cima, who is not involved in the new study.
But, he says, when people who fall into these high-risk groups observed, they should be checked by a doctor who specializes in the identification and treatment of these cancers.