By ANIKA CLARK

Stanley Sikora of Fall River and Tom Souza of Swansea clearly remember when they started their battles with cancer — life-changing moments while raking leaves or shaving, when they touched their necks and felt a lump.

It’s a common experience thanks to a disease that, between the suffering of friends, families and ourselves, has become nearly universal.

But then came news neither expected.

Tumors from both men tested positive for human papillomavirus, an often sexually transmitted virus that is increasingly being linked to cancers of the head and neck.

At Massachusetts General Hospital’s Center for Head and Neck Cancers, “it’s something that we see practically on a daily basis,” said Dr. Lori Wirth, medical director for head and neck oncology, who said in an email that, although there are not-fully-understood co-factors, there’s strong data that about 60-65 percent of all cancers of the oropharynx (the rear of the mouth, including the back of the throat, tonsils and the base of the tongue) are HPV-related.

“Our awareness that HPV is associated with oropharynx cancers is something that has been emerging over the last 5-10 years,” she said. “Ten years ago, we didn’t even look for (it).”

Upon learning of his HPV diagnosis, “I honestly felt creepy about myself,” said Sikora, 59, albeit somewhat reassured when he found out how easily it’s transmitted.

“Already I was shocked that I got cancer. Now it’s from HPV,” he said. “So I’m thinking ‘I can’t be going around telling people I got cancer from that.”

A recent study published in the journal Lancet, however, sheds new light on just how widespread HPV is.

According to U.S. News and World Report, the Lancet study found that 50 percent of male participants were shown through genital swabs to have at least one HPV strain upon enrollment.

Along with cervical cancer and genital warts, HPV is associated with vulvar, vaginal, penile and anal cancer, the Centers for Disease Control and Prevention says.

Head and neck cancer is likewise a major concern as the “fifth most common cancer worldwide,” according to an article in the International Journal of Epidemiology. SouthCoast hasn’t been spared the scourge, with New Bedford and Fall River (excepting Fall River females) exceeding the state’s five-year incidence rate of oral cavity and pharynx cancer, as shown by Massachusetts Department of Public Health statistics from 2003 to 2007.

“The two main risk factors that we’ve known about for years (are) smoking and drinking and then … we’re seeing an increase in the cancers of patients that have no smoking or drinking history,” said Dr. Anthony Fama of Northeast Ear Nose and Throat.

Similarly, at Saint Anne’s Hospital Regional Cancer Care, “In the past year or so, we have seen several cases. Four that come to mind immediately,” of HPV-related head and neck cancer, said Dr. Jason Lee, a radiation oncologist, who said these include three males and one female.

At least half of HPV-positive head and neck cancers are in the oropharynx, with the rest divided among other head and neck sites, according to Dr. Patrick Gagnon, a radiation oncologist at Southcoast Centers for Cancer Care.

“These HPV infections probably occurred decades earlier in most of these patients,” Gagnon said. And “the vast majority of people who are infected with HPV will never get cancer.”

Souza has been married 10 years and didn’t even know what HPV was.

“I always knew about smoking causing cancer,” said Souza, 69, who stopped smoking about 30 years ago. “As far as (an) STD, or any kind of other virus, I just had no idea.”

Andrew Ferreira, a 20-year-old UMass Amherst student from Assonet, said he only recently learned about HPV and said a connection with head and neck cancer definitely concerns him.

However, Cindy Guilbeault — coordinator of Southcoast Hospitals’ Responsible Attitudes toward Pregnancy, Parenting & Prevention, which teaches about sexually transmitted infections and other topics at several local schools — noted higher overall anxiety about STIs among female students than males.

“They don’t take it as seriously in general,” Guilbeault said.

The head and neck cancer connection is so new, it’s yet to be worked into the RAPPP curriculum, although Guilbeault said she expects it will be in the future.

HPV studies are also helping spotlight the riskiness of oral sex. A study published last year in the International Journal of Epidemiology found that in addition to having a history of six or more sex partners, cancer of the oropharynx was associated with a history of four or more oral sex partners.

“There’s some data that shows that HPV present in the oropharynx can be transmitted even by deep kissing,” Wirth said. “Exposure to human papillomavirus is exceedingly common in people who lead normal sex lives.”

The good news? HPV-related oropharynx cancers are more responsive to treatment, according to Wirth. And Souza and Sikora — both Saint Anne’s patients — report successful (albeit grueling) regimens of chemotherapy and radiation.

Both men agreed to share their stories to raise awareness.

“I’m not dead from it, and I’m lucky. … I’m a fighter,” Souza said. “But it’s just a difficult thing to go through.”