A quickly rising incidence of throat and mouth cancers among young American adults may be caused by the sexually transmitted human papillomavirus (HPV).

An analysis of U.S. government health data shows that cancers of the base of the tongue, tonsils, soft palate, and pharynx rose by 60 percent among adults 45 years of age and younger during the past couple of generations. These oropharyngeal cancers struck increasingly more Americans during their vital years between 1973 and 2009, according to a study by researchers from Henry Ford Hospital in Detroit.

When analyzing the data by race, investigators were presented with a mixed bag. The cancers rose 113 percent among whites with a 52 percent drop among African Americans during that period. But Blacks who developed the cancers fared worse than whites and other racial groups when it came surviving the cancer, based on the five-year survival rate.

The most commonly sexually transmitted disease in the United States, HPV infection is usually cleared by the immune system on its own with no complications. Yet, the infection sometimes lingers in the body, with certain types causing genital and anal warts. The most persistent infections by certain strains may eventually lead to cancer, with cervical cancer being the most common of the serious complications.

This summer, Hollywood film actor Michael Douglas told reporters his stage 4 throat cancer had been caused by an HPV infection, which he said he caught by performing oral sex.

Study leader Farzan Siddiqui, director of the Head and Neck Radiation Therapy Program at the research hospital, blamed the rising incidence of oropharyngeal cancers on changes in American culture. "The growing incidence in oropharyngeal cancer has been largely attributed to the sexual revolution of the 1960s and 1970s, which led to an increased transmission of high-risk HPV,” he said in a statement.

However, Siddiqui added that he and his colleagues were puzzled by the divergence between whites and African Americans in infection rates. “We were interested in looking at people born during that time period and incidence of oropharyngeal cancer,” he said. “Not only were we surprised to find a substantial increase in young adults with cancer of the tonsils and base of tongue, but also a wide deviation among [whites] and African Americans with this cancer.”

The study sample of 1,600 patients was racially representative of America during that time period. Whites accounted for 73 percent of the group, most of whom were between the ages of 36 and 44. Following cancer diagnoses, 50 to 65 percent of the patients underwent surgery to remove their tumors, but those who underwent a combination of surgery and radiation had better five-year survival rates.

The investigators planned to present the data at the annual meeting of the American Society for Radiation Oncology in Atlanta, as a preliminary step to publishing a paper in an academic journal. The preliminary data did not specify whether African Americans were more likely to die of oropharyngeal cancers for lack of radiation therapy.