Since its introduction in the 1950s, cervical cancer screening has been considered one of the great success stories in cancer prevention, leading to a dramatic decrease in what used to be the top cause of cancer deaths in women in the United States. Yet about 8 million U.S. women – or one in 10 women in the recommended 21- to 65-year-old age group — have not been screened for cervical cancer in the last five years, according to a report released today by the U.S. Centers for Disease Control and Prevention.
Each year, about 12,000 women get cervical cancer in the United States and about 4,000 die of the disease. It is highly treatable when detected early, but more than half of new cases occur in women who have never, or rarely, been screened.
“We must increase our efforts to make sure that all women understand the importance of getting screened for cervical cancer,” said CDC Principal Deputy Director Ileana Arias in a statement accompanying the report. “No woman should die from cervical cancer.”
The report also served as yet another reminder of the importance of the human papillomavirus (HPV) vaccine as a primary prevention measure to reduce cervical cancer cases and deaths. Persistent infection with certain types of HPV is associated with multiple cancers. Cervical cancer is the most common, afflicting about half a million women worldwide. HPV also is linked to cancers of the vulva, vagina, anus, penis and oropharynx (the middle part of the throat including the soft palate, the base of the tongue and the tonsils).
A team of researchers from Fred Hutchinson Cancer Research Center and the University of Washington, led by Fred Hutch’s Dr. Denise Galloway, was instrumental in laying the groundwork for the HPV vaccine. Galloway and her colleagues also played a pivotal role in identifying how HPV, which is sexually transmitted, causes cancer.
But the number of U.S. adolescents receiving the vaccine has stalled well below goals set by public health experts, who recommend routine HPV vaccination of children aged 11 or 12 years old. Just one in three girls and one in seven boys received the three-dose series last year, according to the CDC.
“The United States is going to be the shame of the developed world because our rates of uptake are so much lower than other countries that have school-based programs to deliver the vaccine,” Galloway said.
Australia’s school-based program, for example, has been an overwhelming success, she said. Begun in 2007, in its first three years the vaccination program reached about 80 percent of its target population: girls aged 12 to13, with a catch-up program for girls and women up to age 26. During that time period, diagnoses of genital warts — which are also caused by HPV —plummeted by 59 percent and high-grade cervical abnormalities also declined.
Because cervical cancer can take decades to develop, the decline in genital warts — which can develop within three months of infection — is an early sign of the vaccine’s effectiveness.
“Their data is just staggering,” Galloway said. “The thing about genital warts is that they’re sort of a quick manifestation of HPV. So you can see the vaccine’s effect in a short time by looking at genital warts. And they’re disappearing.”
Australians have widely accepted the vaccine. By contrast, in the United States, where it has been recommended since 2006 for girls and 2011 for boys, some parents have objected to the vaccine because they feared it would encourage teenagers to have sex or to have riskier sex. Some parents distrust vaccines and pharmaceutical companies in general.
One of the chief obstacles, according to a report issued earlier this year by the President’s Panel on Cancer, is that pediatricians and family doctors don’t routinely recommend the HPV shot along with other vaccines for adolescents, such as meningitis and whooping cough boosters.
According to the new CDC report, that is also one explanation for why women don’t routinely get a Papanicolaou, or Pap, test for cervical cancer: Doctors don’t always recommend it.
Changing guidelines are part of the problem.
Dr. Vicki Benard, a CDC epidemiologist, said that not only are women confused about what the guidelines are but physicians are as well.
The good news is that in 2012, for the first time, three major groups that recommend screening — the U.S. Preventive Services Task Force, American Cancer Society and American College of Obstetrics and Gynecology — agreed on guidelines for when and how often to screen for cervical cancer.
Between the ages of 21 and 29, women whose Pap test results are normal should be retested every three years, Benard said. From ages 30 to 65, women have a choice to take a Pap test every three years or to take both Pap and HPV tests, which can extend the interval between tests to five years.
The Pap test looks for precancers, or changes in the cells of the cervix, which if not treated could develop into cancer. The HPV test looks for the virus that can cause these changes.
Nearly 80 million people in the United States — one in four — are infected with at least one strain of HPV. Most do not know they’re infected, and in most cases, the immune system is able to clear the virus within two years.
Besides confusion about whether and when to screen, other factors that prevent women from being tested are financial barriers, such as lack of health insurance or a regular health care provider, and lack of transportation. Many women may not be aware of free or low-cost screening programs for low-income and uninsured women. In addition, the Affordable Care Act requires that insurance plans as well as Medicare and Medicaid cover cervical cancer screening at no cost.
But as with the HPV vaccine, the biggest factor, Benard said, has been physician recommendations — or rather, the lack thereof.
“There are missed opportunities,” she said. “We’re seeing women in doctors’ offices who have access to care that are not getting screened for cancer.”
Solid tumors, such as those of the cervix, are the focus of Solid Tumor Translational Research, a network comprised of Fred Hutchinson Cancer Research Center, UW Medicine and Seattle Cancer Care Alliance. STTR is bridging laboratory sciences and patient care to provide the most precise treatment options for patients with solid tumor cancers.
Mary Engel is a former staff writer at Fred Hutchinson Cancer Research Center. Previously, she covered medicine and health policy for the Los Angeles Times, where she was part of a team that won a Pulitzer Prize for Public Service. She was also a fellow at the Knight Science Journalism Program at MIT. Follow her on Twitter @Engel140.