Study Finds HPV Screening May Be More Sensitive Than Pap Test for Detecting Cervical Cancer
The main goal of cervical screening programs is to detect and treat precancer before the cancer develops. Human papillomavirus (HPV) testing is more sensitive than cytology for detecting precancer. However, reports of rare HPV-negative, cytology-positive cancers are motivating the continued use of both tests (co-testing) despite increased testing costs.
A study by Schiffman et al evaluating the relative contributions of the HPV and cytology test components of co-testing in the detection of cervical precancer and cancer has found that HPV testing alone identified more women subsequently diagnosed with cancer and precancer than the Pap test. Given the rarity of the cancers among screened women, the contribution of cytology to screening translated to earlier detection of at most five cases per million women per year, according to the study. Excessive screening could have minimal cancer prevention benefits while increasing the harms of screening, concluded the researchers. The study was published in the Journal of the National Cancer Institute.
Study Methodology
The researchers quantified the detection of cervical precancer and cancer by co-testing compared with HPV testing alone using data obtained from Kaiser Permanente Northern California (KPNC). They analyzed data from women ages 30 years or older who underwent triennial cervical co-testing from January 2003 to December 2015.
Screening histories preceding cervical cancers (n = 623) and precancers (n = 5,369) were examined to assess the relative contribution of the cytology and HPV test components in identifying cases. The performances of HPV testing and cytology were compared using contingency table methods, general estimating equation models, and nonparametric statistics; all statistical tests were two-sided.
Study Findings
The researchers found that HPV testing identified more women subsequently diagnosed with cancer (P < .001) and precancer (P < .001) than cytology. HPV testing was statistically significantly more likely to be positive for cancer at any time point (P < .001), except within 12 months (P = .10). HPV-negative/cytology–positive results preceded only small fractions of cases of precancer (3.5%) and cancer (5.9%). These cancers were more likely to be regional or distant stage with squamous histopathology than other cases. Given the rarity of cancers among screened women, the contribution of cytology to screening translated to earlier detection of at most five cases per million women per year. Two-thirds (67.9%) of women found to have cancer during 10 years of follow-up at KPNC were detected by the first co-test performed.
“The added sensitivity of co-testing vs HPV alone for the detection of treatable cancer affected extremely few women.… Excessive screening in an attempt to prevent every case [of cervical cancer] could have minimal cancer prevention benefits while increasing the harms of screening,” concluded the study authors.
Mark Schiffman, MD, MPH, of the Division of Cancer Epidemiology and Genetics at the National Cancer Institute, is the corresponding author of this study.
Funding for this study was provided by the National Cancer Institute.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
