Cervical Cytology Specimen Stability in Surepath Preservative and Analytical Sensitivity for HPV Testing with the cobas and Hybrid Capture 2 Tests

Evaluation of two alternative non-alcohol-based media for the suspension of self-collected vaginal swabs for HPV testing in cervical cancer screening

The introduction of Human Papillomavirus (HPV) testing in cervical cancer screening enhanced the opportunity to introduce self-collection as an innovative approach to improve coverage rates. Validation and standardization of the pre-analytical and analytical procedures are crucial for the quality assurance of HPV tests on self-collected samples. This study evaluated the analytical performance and the stability of self-collected vaginal samples resuspended in 5 mL of two non-alcohol-based media, eNat® and MSwab® compared to a professionally collected cervical sample, resuspended in 20 mL ThinPrep®, for the detection of high-risk HPV (hrHPV). The impact of the suspension volumes on analytical performance was also evaluated (2 and 5 ml). A good analytical concordance in hrHPV detection in cervical and vaginal self-collected swabs suspended in 5 ml of both non-alcohol-based media was demonstrated (eNat®: 91.2 %, k = 0.821; MSwab®: 91.4 %; k = 0.798). A similar analytical performance was found for samples resuspended in 2 mL (eNat®: 92.9 %, k = 0.811; MSwab®: 92.9 %, k = 0.811) compared to cervical samples. Good nucleic acid stability was demonstrated for vaginal samples stored at 20-25 °C and 37 °C for up to 4 weeks. Results of this preliminary study support the introduction of these media for vaginal self-sampling-based prevention programs. Nevertheless, further research is necessary to evaluate clinical accuracy in larger settings.

Validation of cobas 4800 HPV assay in SurePath Papanicolaou specimens for cervical cancer screening

INTRODUCTION

The cobas (Roche Diagnostics, Indianapolis, IN) HPV assay was approved by the US Food and Drug Administration for human papillomavirus (HPV) testing in SurePath (Becton Dickinson, Franklin Lakes, NJ) Papanicolaou specimens for cervical cancer prevention. To validate the cobas HPV assay in SurePath specimens in our institution, we compared its accuracy and clinical efficacy to that of the Cervista (Hologic, Marlborough, MA) HPV HR assay.

METHODS

This study used 138 Papanicolaou (Pap) cytology specimens collected in SurePath preservative fluid at our institution in 2018. After Pap cytology testing, the residual specimens were split for testing with the cobas and Cervista assays. Polymerase chain reaction (PCR)-based HPV testing (GP5+/GP6+) was performed on specimens with discrepant results. Clinical follow-up data were reviewed.

RESULTS

The cobas HPV and Cervista HPV HR assays showed good concordance (89.1%), with a kappa value of 0.78 (95% CI: 0.675-0.885). Fifteen specimens showed discrepant results between the 2 assays. Of 7 cases with cobas+/Cervista- results, 5 (71%) were confirmed positive by PCR. Of 8 cases with cobas-/Cervista+ results, 4 (50%) were confirmed positive by PCR. cobas HPV and Cervista HPV HR showed the same HPV-positive rate in cases of pathologically diagnosed ASC-H, LSIL, or HSIL. The sensitivities and specificities for detecting high-risk HPV of cobas HPV (93.7%, 97.3%) and Cervista HPV HR (92.1%, 94.7%) were comparable. The cobas HPV assay had false-negative results in 4 cases (5.2%) including 1 false-negative case that failed to predict CIN3.

CONCLUSIONS

The cobas HPV assay is valid in SurePath Pap cytology specimens for cervical cancer screening but has limitations of false-negative results with clinical implications.

Infección por Virus del Papiloma Humano y citología cérvico-vaginal en mujeres indígenas del Cañar, Ecuador

There are few studies on the circulation of Human Papilloma Virus (HPV) in indigenous Ecuadorian women. The aim of the study is to determine the circulation of HPV and identify cytological alterations in cervical samples of indigenous Ecuadorian women and to define the behavior of some socio-demographic and clinical-epidemiological variables. An analytical cross-sectional study was done between July 2017 and September 2018 to determine the presence of cytological alterations and HPV infection in 100 indigenous women between 15 and 55 years of age, residing in Cañar, Ecuador. The association between socio-demographic and clinical-epidemiological variables with viral infection was investigated. Was obtained a 98% of negative cytology for malignancy and 2% of cervical lesions. Cases with high-grade lesions were not diagnosed. In general, a 34% (34/100) tested was positive for HPV, predominating oncogenic genotypes. HPV 31 was the most frequent in 41.2% (14/34) of cases followed by HPV 16 in 20.6% (7/34). Women between 20 and 30 years of age were five times more likely to be infected with HPV (44.1%, 15/34). The frequency of infection was significantly higher in single women and in those who reported having 2 to 3 births. Infection with HPV 16 was associated with the use of hormonal contraceptives, in 57.1% (4/7) of the cases; p = 0.005, RP = 12.44 IC95% (2.40-64.62). The high prevalence of oncogenic HPV infection indicates the need to incorporate this indigenous population into early detection programs for cervical cancer.

Stability Study of Cervical Specimens Collected by Swab and Stored Dry Followed by Human Papillomavirus DNA Detection Using the cobas 4800 Test

Safer, more convenient methods for cervical sample collection and storage are necessary to facilitate human papillomavirus (HPV) DNA testing in low-resource settings. Our study aimed to evaluate the stability of cervical specimens collected with dry swabs and stored dry, compared to liquid-based cytology (LBC) samples, as detected by HPV DNA testing. Women with abnormal cytological findings or HPV-positive results at colposcopy were recruited from the West China Second University Hospital, Sichuan University, between October 2013 and March 2014. From each woman, physicians collected cervical specimens with a swab placed into a Sarstedt tube and a CytoBrush placed into LBC medium. Samples were randomly assigned to be stored at uncontrolled ambient temperature for 2, 7, 14, or 28 days and then were tested for 14 high-risk HPV (HR-HPV) types using the cobas HPV test. The rates of agreement between dry swab and LBC samples for any HR-HPV type, HPV16, HPV18, and the 12 pooled HR-HPV types were 93.8%, 97.8%, 99.4%, and 93.2%, respectively, with kappa values of 0.87 (95% confidence interval [CI], 0.83 to 0.91), 0.94 (95% CI, 0.91 to 0.97), 0.94 (95% CI, 0.87 to 1.00), and 0.86 (95% CI, 0.82 to 0.90). The performance of swab samples for detection of cervical precancerous lesions by means of cobas HPV testing was equal to that of LBC samples, even with stratification by storage time. Dry storage of swab-collected cervical samples can last for 1 month without loss of test performance by cobas HPV testing, compared to LBC samples, which may offer a simple inexpensive approach for cervical cancer screening in low-resource settings.