Early Detection
Combination of Pap Test, HPV Test is Cost-Effective Means of Cervical Cancer Screening, Two JAMA Studies Find
Using a Pap test in conjunction with human papillomavirus screening every two years is a cost-effective way for women to be tested for cervical cancer, according to a study in today's issue of the Journal of the American Medical Association. Researchers from Georgetown University Medical Center used a mathematical model to compare the costs of several cervical cancer screening methods with the quality-adjusted life-years saved for each regimen. Three screening regimens were examined: a Pap test plus an HPV test; a Pap test alone; and an HPV test alone. Each of the testing regimens was conducted every two years or every three years, as such intervals most closely reflect current professional guidelines and clinical practice. The study examined the cost-effectiveness of using each screening method on women during one of three possible age ranges: 20 to 65, 20 to 75 or 20 until death. The researchers operated under the assumptions that all cervical neoplasia indicates underlying HPV infection and that a finding of atypical squamous cells of uncertain significance (ASCUS) constitutes a negative test result. The researchers found that the effectiveness in detecting precancerous cells was generally equal for either an HPV test alone or a Pap test alone, although offering single HPV tests is costlier than providing Pap tests. The combination of an HPV test plus a Pap test provided "maximal savings in life years" when offered without an upper age limit; using a combined screening regimen for women until age 75 captured 97.8% of the benefits achievable by continuing to screen until death, and stopping screening at age 65 captured 86.6% of the benefits of screening until age 75. In addition, the study showed that adding HPV testing to lifetime biennial Pap screening can help prevent 225 cases of invasive cervical cancer per 100,000 women and can decrease cervical cancer mortality by an additional 59% over the use of a Pap test alone (Mandelblatt et al., JAMA, 5/8).
Managing ASCUS With HPV Test
A second study in JAMA evaluated the cost-effectiveness of several different methods of managing women whose Pap tests indicate ASCUS, an abnormal result that may or may not indicate cancerous or precancerous cells (Kim et al., JAMA, 5/8). New guidelines from the 2001 Bethesda convention that were published in the April 24 issue of JAMA stated that women with ASCUS should undergo either two repeat Pap tests, an immediate colposcopy -- an outpatient procedure in which the cervix is examined and biopsied -- or a DNA-based HPV test. The HPV test is the preferred option in instances when the newer liquid-based Pap tests have been used, the guidelines state (Kaiser Daily Reproductive Health Report, 4/24). The current JAMA study compared four management strategies for ASCUS: immediate colposcopy, repeat Pap tests, HPV test or ignoring the test result. The least costly option, after ignoring the result, was to conduct "reflex" HPV DNA testing, in which an HPV test is performed on the same sample that was collected at the time of the initial Pap test. Both the repeat Pap testing strategy and the regimen of delayed HPV testing requiring a return visit were shown to be more costly and less effective than reflex HPV testing. "Reflex HPV DNA testing provides the same or greater life expectancy benefits and is more cost-effective than other management strategies for women diagnosed as having ASCUS," the researchers state, noting that switching from annual conventional Pap tests to biennial liquid-based Pap tests combined with reflex HPV testing could save more than $15 billion over the lifetime of a cohort of women ages 18 to 24. "[T]he aggregate health economic costs saved by adopting such a policy [for women with ASCUS] would be enormous," the study concludes (JAMA, 5/8).
Gauging Cost-Effectiveness
Although the two studies demonstrated which cervical cancer screening regimens are the most cost-effective, they cannot predict which regimens will be preferred in the marketplace, Dr. David Mark, a contributing JAMA editor, writes in an accompanying editorial. "A critical examination of actual medical practice to observe where it appears to be limited or affected based on cost-effectiveness would probably reveal wildly inconsistent cost-effectiveness thresholds," Mark states (Mark, JAMA, 5/8). For example, insurers may be reluctant to cover Digene Corp.'s new HPV DNA test because it costs more than a normal Pap test and because the costly colposcopy procedure could become more prevalent if the HPV test is widely used (Kaiser Daily Reproductive Health Report, 5/2). But there are ways to make HPV screening more efficient and effective, Mark writes. He notes that the models used in the two JAMA studies assume that HPV infection occurs randomly in the population, but it is "more likely that HPV infection is non-randomly distributed in the population due to behavioral and possibly genetic determinants." Screening programs could be modeled to take advantage of this varying level of risk by "stratify[ing] women into different screening regimens depending on their HPV status," with women who test negative for HPV receiving screening at intervals of several years, and women who have tested positive for HPV receiving screenings at more frequent intervals (Mark, JAMA, 5/8). See more information on this topic under the NCCC Health News section www.nccc-online.org and the NCCC Research and Treatment section.
