May 23 (Reuters) - Vaccination of boys and men against

the human papillomavirus (HPV) reduces their risk of head and

neck cancers and other malignancies, a new analysis shows,

adding to the vaccine's proven benefit in protecting women from

cervical cancer.

The study of more than 3.4 million people is one of the

first long-term analyses of the vaccine's real-world effect on

preventing HPV-related cancers of the head and neck, anal areas,

penis, vulva, vagina and cervix, researchers said.

Previous studies of the vaccine have focused mainly on

cervical cancer. In one large 2020 study from Sweden, for

example, cervical cancer rates were 47 per 100,000 in vaccinated

women and 94 per 100,000 in unvaccinated women.

The new study, scheduled for presentation at the upcoming

American Society of Clinical Oncology meeting in Chicago,

included more than 1.7 million volunteers who were vaccinated

against HPV since 2010, at some point between ages 9 and 39, and

roughly equal numbers of similar unvaccinated volunteers. About

44% were male.

Vaccinated males had lower rates of any HPV-related cancer

and of head and neck cancers (3.4 and 2.8 cases, respectively

per 100,000 vaccinated patients, compared with 7.5 and 6.3,

respectively, per 100,000 unvaccinated patients), the study

found.

Smoking was formerly the main driver of many head and neck

cancers - such as cancers of the mouth and throat - but today

the main cause is HPV infections, ASCO President Dr. Lynn

Schuchter said on Thursday at a press briefing. Schucter was not

involved in the study.

The new study "extends what we know" and shows that

preventing infection with the vaccine helps prevent these

additional HPV-related cancers, she added.

Vaccinated females had a lower risk of any HPV-related

cancers in the study and, as expected, a lower risk of cervical

cancer, compared with unvaccinated females.

Vaccination did not significantly reduce their risks for

head and neck cancers and vulvar or vaginal cancer.

Merck's ( MRK ) HPV vaccine was approved in 2006 for girls and women

ages 9 to 26 and in 2009 for boys and men in that age group. The

most recent version, Gardasil 9, has been approved in the U.S.

since 2018 for use in children and adults ages 9 through 45.

A separate study to be presented at the ASCO meeting found

that between 2011 and March 2020, U.S. uptake of the HPV vaccine

rose from 23.3% to 43.0% of the eligible population, improving

from 7.8% to 36.4% in males and from 37.7% to 49.4% among

females.