Cancer and its viral perpetrators have one tenacious foe in Dr. Denise Galloway, a researcher in Fred Hutchinson Cancer Research Center's Human Biology Division.
Galloway has been investigating the link between the two since 1978, when she and her late husband, Dr. Jim McDougall, joined Fred Hutch as founding faculty members. Since then, she's made remarkable discoveries, demonstrating that human papillomaviruses (HPVs) are associated with nearly all genital tract cancers as well as some head and neck cancers. Her work has also paved the way for a vaccine against high-risk HPVs, which has helped prevent cervical cancer in hundreds of thousands of women worldwide.
"When I started working on this, we didn't know what caused cervical cancer," she said of her years of research and collaboration with scientists at the University of Washington. Work developing virus-like particles that became the foundation for HPV vaccines was carried out in the Galloway Lab and also at the University of Queensland in Australia, the National Institutes of Health, Georgetown University and elsewhere. "Now we have a vaccine that can prevent HPV-associated cancers," she said.
The vaccine is exceptionally effective. In June, the U.S. Centers for Disease Control and Prevention announced that since the HPV vaccine was introduced in 2006, HPV has dropped 56 percent in girls between 14 and 19 years old.
Even better, young girls in developing countries will soon have greater access to the vaccine, thanks to the makers of Gardasil and Cervarix, which recently agreed to lower the price from $300 for three doses to just $5 per dose.
According to the Centers for Disease Control and Prevention, genital HPV affects nearly all sexually active men and women at some point in their lives. While most HPV infections are cleared by the body's immune system, a small percentage go on to create abnormal cells which, over the years, can become cancerous.
"Many people have HPV infections, but cancer is a rare outcome," said Galloway, pointing to the effectiveness of Pap smears and treatment tools like laser and cryotherapy, both used to eliminate premalignant lesions.
But not everyone has access to cervical cancer screenings.
"The rates of this cancer differ eightfold throughout the world," Galloway said. "In parts of the world where there's no screening at all, the cumulative lifetime risk is about 1 to 2 percent."
Worldwide, that adds up to about 570,000 cases of cervical cancer each year, making it the second most common cancer in women. Nearly half of those cases — approximately 250,000 — prove fatal. All are linked to some type of HPV.
Despite its potential for harm, Galloway said the molecular nature of the human papillomavirus is rather simple, especially when compared to viruses like HIV.
Galloway and her team first created HPV-like particles in 1992 and were soon injecting them into mice to trigger an antibody response. As hoped, the response neutralized the virus and prevented it from getting into cells.
Clinical trials followed, along with the remarkable news that the vaccine — similar to the virus except for the lack of disease-causing DNA — prevented nearly 100 percent of high-grade cervical pre-cancers and non-invasive cervical cancers associated with HPV 16 and HPV 18, the two types responsible for 70 percent of cervical cancers. The vaccine also protects young girls and boys from contracting genital warts and anal cancer, also associated with certain HPVs.
Today, Galloway is searching for other cancers that are triggered by viruses in hopes that vaccines can be developed to prevent them, as well.
She and her team are working on one: Merkel cell carcinoma, a rare and aggressive skin cancer. "There's a virus that's in the cells," she said. "It's not the same as HPV but it's like a cousin."
After three decades of sleuthing, Galloway is still very much on the viral cancer case.
"Not all cancers have a viral origin," Galloway said, pointing to lung cancer, squamous cell skin cancer and lymphoma as cancers that may also have a viral cause. "But there are certain ones that have a smoking gun."