When Henrietta Lacks was being treated for cervical cancer more than 60 years ago, her cells were taken for medical research without her consent. This ethical controversy became the subject of a 2010 best-selling book, Rebecca Skloot’s The Immortal Life Of Henrietta Lacks, and now an HBO movie of the same name starring Oprah Winfrey.

Despite radiation therapy and surgery, Lacks died from the cancer in 1951. But her cells, known to scientists as HeLa cells, have played a role in many scientific advancements ― and have helped protect other young women from the cervical cancer that took Lacks’ life.

Each year, some 12,000 women in the U.S. are diagnosed with cervical cancer, and 4,000 women die from it. Because not all HPV infections lead to cervical cancer, there are no estimates available of how many cases of cervical cancer were prevented thanks to the HPV vaccine, and, ultimately, the HeLa cells.

However, HPV vaccinations do prevent infections from two high-risk viruses that cause 70 percent of cervical cancers, and virtually all cases of cervical cancer are caused by HPV.

Because the HeLa cells came from a cancerous tumor, they multiplied quickly, allowing scientists to start a line of human cells that can live outside the body. Every 24 hours, a new generation of cells is reproduced, creating a wealth of biological material to work with.

“It is well acknowledged that many biological discoveries wouldn’t have been possible without the HeLa cell line,” said Dr. Jasmin Tiro, an associate professor in the clinical science department at the University of Texas Southwestern Medical Center.

How HeLa Cells Led To A Vaccine For HPV

In the 1980s, the German virologist Harald zur Hausen found that HeLa cells contained human papillomavirus 18 (HPV-18), one of the strains of HPV that can cause cervical cancer. Scientists used this cell line to help develop an HPV vaccine, which was introduced in 2006 and has since helped reduce HPV cases in teenage girls by almost two-thirds.

“HPV can cause an infection that can be persistent,” Tiro said. “It can cause abnormal precancerous cells in various parts of the body. If your body can’t eradicate that infection, those precancerous cells can progress and lead to cervical cancer.”

When HPV-18 inserts its DNA into healthy cells, the cells start producing proteins that can lead to cancer. However, not all people with HPV develop cancer. If the virus causes the cells to become genetically unstable, and compromises their ability to fight off tumors, the results can be deadly ― as they were for Lacks.

Doctors use two tests to screen women for cervical cancer: an HPV DNA test to detect the risk of the virus developing into cancer, and a Pap test to detect precancerous cells in the cervix.

Right now, Tiro and Dr. Rachel Winer, an associate professor at the University of Washington’s department of epidemiology, are working on a trial to mail HPV self-screening kits to under-screened women, in hopes that this can increase the rate of screenings, preventing HPV and cervical cancer.

The HPV Vaccine Still Faces Resistance

Many women may not prioritize getting screened, and according to a study, fewer than half of women know that HPV can cause cervical cancer. What’s more, since HPV is a sexually transmitted infection, it can be stigmatizing for women.

“Some women don’t necessarily see screening as important,” Tiro said. “Those at risk for developing cervical cancer are young women, mothers, and they might not be prioritizing screenings at that time. Sometimes it’s that they don’t have regular contact with the health care system.”

The Food and Drug Administration has not yet approved home screenings for HPV, so these early efforts are simply a trial. However, doctors do recommend the HPV vaccine. The newest formulation of the vaccine prevents nine HPV strains known to cause cervical cancer, as well as anal, oral, head and neck cancers.

The U.S. Centers for Disease Control and Prevention recommends the HPV vaccination for children ages 11 and 12, though doctors often don’t push the HPV vaccine the way they do with other children’s vaccinations. Many parents hesitate to let their children get the vaccine due to general misconceptions about vaccine safety, even though scientific evidence shows that they reduce the risk of disease in children.