Self-collected HPV specimens may help detect cervical cancer sooner than cytology, according to study results.
The self-collected method also may help reduce patient costs and boost coverage, researchers wrote.
Although cytology-based screening has helped reduce the percentage of cervical cancers, it often must be repeated to help identify underlying abnormalities that eventually could prove to be cancerous.
HPV testing has demonstrated greater specificity and sensitivity than cytology-based screening for identification of precancerous lesions, according to study background. HPV testing also has the advantage of self-administration, as women can collect necessary samples themselves in a noninvasive manner and likely at reduced cost.
Carolina Porras, MS, of the Proyecto Epidemiologico Guanacaste, Fundacion INCIENSA in Costa Rica, and colleagues performed a secondary analysis of a large Costa Rican HPV vaccine trial to determine whether self-collected HPV samples could detect cervical intraepithelial neoplasia grade 2 or higher adenocarcinomas and do so with the same accuracy as HPV tests administered by a clinician.
Researchers identified a full analytical cohort of 5,109 women from the original enrollment in the Costa Rica Vaccine Trial. The women were aged 18 to 25 years, and all had a self-collected HPV sample with an available HPV-polymerase chain reaction result at their 6-month follow-up. A subset of 615 women also had clinician-collected specimens at the 6-month follow-up.
Patients underwent annual follow-up for 4 years. The median age at the 6-month follow-up was 22 years. The median follow-up for the full cohort was 54 months (range, 9-76 months), and median follow-up for the subset was 55 months (range, 10-74 months).
In the full cohort, one-time HPV testing on self-collected specimens detected prevalent CIN2+ with a sensitivity of 88.7% (95% CI, 77-95.7) and a specificity of 68.9% (95% CI, 67.6-70.1). During the subsequent 4 years, sensitivity was 73.9% (95% CI, 65.8-81) and specificity was 69.4% (95% CI, 68.1-70.7).
In the subset of women who also had clinician-collected specimens, self-collected HPV was considerably more sensitive than cytology (80% vs. 10%), and the relative sensitivity was 0.1% (95% CI, 0.03-0.5).
Women with normal baseline cytology were nearly three times more likely than those with a negative self-collected HPV sample to subsequently develop CIN2+ (relative complement of the negative predictive value = 2.9; 95% CI, 1-8.3).
Overall, self-collected samples were comparable to those collected by clinicians with regard to their ability to identify carcinogenic HPV types (89%; kappa = 0.78, McNemar test = 0.62).
“The similar performance of the self-collected and the clinician-collected HPV test for detection of prevalent and incident disease indicate that this could represent an invaluable tool for improving screening coverage,” the researchers wrote. “Our data indicate that PCR HPV testing on a self-collected sample is feasible and well-accepted and provides sensitivity and specificity comparable with clinician-collected specimens. In addition, it detects disease earlier than cytology and should be considered in cervical cancer screening programs to reduce cost and improve coverage.” – by Anthony SanFilippo
Disclosure: The researchers report no relevant financial disclosures.
Noelle Gillette Cloven
HPV DNA testing as primary screening for cervical cancer has recently become FDA approved and has been supported by medical societies as an alternative to Pap smear for women aged 25 years and older. Multiple large randomized trials performed in Europe and the United States have demonstrated exceptionally low rates of CIN 3 for up to 5 years in women who test negative for high-risk HPV DNA.
Considerable progress has been made in decreasing cervical cancer incidence and deaths in industrialized countries, but cervical cancer remains a leading cause of death in women in underdeveloped countries. In addition, there are barriers to screening even in the United States, where as many as half of patients diagnosed with cervical cancer have not been screened.
The current paper evaluated the use of self-collected HPV samples in a group of young women enrolled in a large vaccine trial and followed for at least 4 years. The goal of this screening approach is to increase the number of patients screened and possibly decrease costs. The success of this approach depends heavily on patient acceptance, compliance and reliability. In this large prospective trial — in which half of patients were vaccinated — the self-collected HPV samples 6 months after enrollment performed well in the detection of CIN2 or greater and had good concordance with physician-collected samples.
A widely used example of self-screening for cancer is self-breast exams. Although the impact of self-breast exams on survival is debatable, it is a common recommendation as part of general health maintenance. Patient compliance with self-screening breast exams is reported to be 20% to 40%. Studies show that women who perceive themselves to be at increased risk are more likely to perform exams, emphasizing the importance of patient education to ensure success of a self-screening program. Although the current study shows self-screening for HPV to be effective, it remains to be determined if this will be true for the general population or just highly motivated subsets.
Many questions remain prior to widespread adoption of this method, including the appropriate age and screening interval, and — most importantly — reliability of follow-up of abnormal test results. At this point, it is unclear how to manage a positive HPV test, particularly in young women who have the highest prevalence of HPV positivity. Cost-effectiveness of this approach, if it leads to increased colposcopies and biopsies, is questionable. There also is a concern about overtreatment of transient HPV infections.
Increasing vaccination and decreased prevalence of HPV in younger generations make this a more attractive approach for the future. Based on this study and other large clinical trials, women with negative HPV DNA testing can be reassured that the risk for serious dysplasia is low for several years. Going forward, we need to remain committed to screening patients and educating both the public and physicians about new guidelines.