A new study has found that up to 11 million American men were actively infected with cancer-causing human papillomavirus (HPV) between 2011 and 2014. 

The study, published in the journal Annals of Internal Medicine, says about one in nine U.S. men has oral HPV. 

Experts say HPV is among the most common sexually-transmitted disease and is often symptomless. The study found that 3.2 percent of American women also have HPV.

Dr. Randolph DiLorenzo, of Northwell Health, says HPV is being called a silent cancer among men. 

"Women are always getting pap smears and getting screened for this, but the men don't understand they are at risk…and they would benefit from getting the vaccine," said Dr. DiLorenzo.

Testing for oral HPV is limited at best. The only way to prevent infection is by abstaining from sexual activity, using protection or by getting the HPV vaccine. Doctors say most men are unaware that a vaccine is available to them. Pediatricians say twice as many females are inoculated for the virus than males. 

"This is an equal opportunity disease," said Dr. John Zaso. "It is very important that they are both immunized." 

According to the Centers for Disease Control, 3,700 people die in the U.S. each year from cancers linked to HPV.