A strain of human papillomavirus called
HPV 18, which is found in up to 30 percent of women with cervical cancer,
appears to be associated with a mortality rate that's nearly double that of
other HPV-related cervical cancers, according to a Fred Hutchinson Cancer
Research Center study.
Results of the research, published Friday in the Journal of Clinical
Oncology, confirm several previous, smaller studies that suggest HPV 18 may be
an excellent molecular tumor marker for predicting the prognosis of women
diagnosed with early-stage cervical cancer.
The National Cancer Institute-funded project, led by Stephen Schwartz,
Ph.D., and colleagues, is the largest, most comprehensive and first
population-based study to assess the viability of HPV 18 as a prognostic tumor
marker for invasive cervical carcinoma.
"I think that the study potentially has very important clinical
implications, as well as implications for new basic research," said Schwartz,
an associate member of the Hutchinson Center's Public Health Sciences
Division. "What is needed now is a trial to see if measuring the presence of
HPV 18 in the tumors of cervical-cancer patients makes a difference in
clinical outcome in terms of using this information to make treatment or
In other words, women with poorer prognosis, whose cervical tumors harbor
HPV 18, perhaps could be treated more aggressively in the first place and
monitored more frequently after initial treatment.
The findings also could impact the development of HPV vaccines for both
treatment and prevention. "We don't know yet if such vaccines work, but if
they do, there could be a trend toward patients getting their tumors tested to
determine what strain of HPV is present, and then vaccinating them against
that particular strain," said Schwartz, also an associate professor of
epidemiology at the University of Washington School of Public Health and
Human papillomavirus, a sexually transmitted disease that is the primary
cause of cervical cancer, is present in virtually all cases of invasive
cervical cancer. It is estimated that more than 6 million women in the
United States are infected with HPV, of which there are more than 100 types.
While all types can cause the growth of abnormal cells, usually only the
high-risk variety -- about a dozen of which so far have been identified
-- have been linked to cancer.
Schwartz and colleagues followed 399 women in western Washington with
invasive cervical cancer at various stages. The women came from King, Pierce
and Snohomish counties and were treated at a variety of hospitals. The women
were followed for more than four years on average.
While the majority of these women tested positive for HPV 16 -- the most
common HPV strain linked to cervical cancer, accounting for about half of all
cases -- about 20 percent of the women in the study had HPV 18-related tumors.
Adjusting for age, cancer stage and histological type, the risk of dying from
cervical cancer was increased two-fold for patients whose tumors contained HPV
18 DNA compared to those whose tumors contained HPV 16 DNA.
The molecular mechanisms that cause HPV 18 to be associated with poor
prognosis are unknown; basic research is needed to identify this link so new
therapies can be developed to counteract this fast-growing, aggressive form of
cervical cancer. Understanding these yet-to-be identified mechanisms, which
may also be present at lower levels in other types of cervical cancer, could
reduce deaths among all women with invasive cervical cancer.
"Although a tumor marker such as HPV 18 can be clinically valuable even
when we don't know everything about what it does physiologically, knowing the
mechanisms should maximize our ability to design treatments to counteract the
marker's effect," Schwartz said.