Self-sampling of vaginal fluid and high-risk human papillomavirus testing in women aged 50 years or older not attending Papanicolaou smear screening

Authors


M Lindell, Department of Pathology and Cytology, Uppsala University Hospital, S-751 85 Uppsala, Sweden. Email monica.lindell@akademiska.se

Abstract

Please cite this paper as: Lindell M, Sanner K, Wikström I, Wilander E. Self-sampling of vaginal fluid and high-risk human papillomavirus testing in women aged 50 years or older not attending Papanicolaou smear screening. BJOG 2012;119:245–248.

Objectives  To study the value of self-sampling of vaginal fluid at home in combination with high-risk human papillomavirus (HPV) testing in a cohort of older women not attending Papanicolaou (Pap) smear screening.

Design  Women (n = 3618), aged 50–65 years, who had not attended screening for at least 6 years were offered self-sampling of vaginal fluid at home (study cohort). The collected material was analysed for the presence of high-risk HPV (using Hybrid capture 2; Hc2). Women with a positive HPV test were referred for colposcopy. These results were compared with the results of Pap smear screening in a corresponding age group of women (controls). The end point of the study was identification of a histological cervical intraepithelial neoplasia stage 2 (CIN2) and above (CIN2+).

Results  In all, 39.4% (n = 1426) women participated and 4.6% (n = 66) were high-risk HPV positive. Of the HPV-positive women 56 chose to attend a surgery (84.8%) after a mean time of 2.1 months and ten of these women (17.9%) showed CIN2+, corresponding to 0.70% of all participating women. In the controls, who participated in organised Pap smear screening, the prevalence of CIN2+ was 0.25% (15/6048). The odds ratio for identification of CIN2+ in women aged 50 years or older performing self-sampling and HPV test in comparison with Pap smear was: 2.84 (95% CI 1.14–6.77, P = 0.0174). In older women primary high-risk HPV testing (Hc2) and Pap smear screening showed equal specificity of around 96%.

Conclusions  Self-sampling of vaginal fluid in combination with high-risk HPV testing appears to be an attractive method to improve screening coverage and decrease the prevalence of cervical cancer in women aged 50 years or older.

Introduction

In countries with nationwide gynaecological screening, most invasive cervical carcinomas occur in women who choose not to participate in the Papanicolaou (Pap) smear screening. Furthermore, most cancers occur in postmenopausal women.1–3

Numerous reports show that more cervical intraepithelial neoplasia stage 2+ (CIN2+) lesions on the cervix are identified in women when primary cytological screening is replaced by primary high-risk human papillomavirus (HPV) testing.4–7 However, one disadvantage with HPV testing is that the method is considered to have a low specificity.4,5 Many HPV infections are transient and a number of women will be unnecessarily examined, especially young women, who are frequently HPV positive.8–10 In addition, there is no available treatment for genital high-risk HPV infection without concomitant cytological alterations. For this reason, it is considered that the identification of a high-risk HPV infection may cause the investigator more concern than actually providing valuable information.

To address the question of the value of primary high-risk HPV screening in older women, a cohort study was performed. The included women had not participated in the organised cytological screening in the last 6 years or longer. They were offered the opportunity to perform self-sampling of vaginal fluid at home in combination with high-risk HPV testing.11,12 The result of the study was compared with a historical group of women of corresponding age who participated in organised cytological screening.

Methods

In Sweden, women aged 25–60 years are invited for Pap smear screening every third year. Women, who have not attended for over 4 years are sent a reminder letter once a year.

During January 2008 to May 2010, a total of 4016 women aged 50–65 years who had not participated in organised cytological screening for >6 years were offered self-sampling of vaginal fluid at home (Qvintip®, Aprovix AB, Uppsala, Sweden). This method has previously been described in detail.11,12 The women were sent an information letter containing a telephone number to call if any uncertainty regarding the home sampling method was experienced. The letter also contained instructions for delivering the self-sampling device. After collection of vaginal fluid the sample was sent in a prepaid envelope to our laboratory for high-risk HPV testing with the Hybrid capture 2 method (Hc2). The test identifies 13 high-risk HPV-types (16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59 and 68). The Hc2 technique can detect HPV DNA concentrations over 1 pg/ml, which is proportional to the light emission of the positive control and corresponds to 5000 HPV genomes per specimen in the well. Participation was free of charge.

Of the 4016 women in the study group, 398 (9.9%) were regarded as inactive because of incorrect address or a previous hysterectomy. Finally, 3618 women were included in the study. Of these women, 39.4% (n = 1426) chose to perform self-sampling of vaginal fluid followed by sending the collected material for HPV analysis. The HPV-negative women received, within a few weeks, a letter informing them of the negative results. The women who were HPV-positive received a letter offering them an examination at a gynaecological surgery including colposcopy and cervical biopsy within a time interval of 2–3 months.

At our Department of Pathology and Cytology all laboratory analyses are collected in a central database (SymPathy, Tieto AB, Malmö, Sweden). The analyses include cytological smears in the organised screening, histological examinations and HPV tests. Women can be identified by their personal identification number and the analyses by specific topographic and morphological codes: SNOMED (Systematised, Nomeclature Of MEDicine, College of American Pathologists, Skokie, IL, USA). The database was used to follow up high-risk HPV-positive women performing self-sampling of vaginal fluid at home. In the organised Pap smear screening programme in the County of Uppsala, squamous cells in smears were diagnosed as Normal, ASCUS (atypical squamous cells of undetermined significance), CIN1, CIN2 and CIN3, according to the recommendations of the National Board of Gynaecological Screening in Sweden. All women, aged 50–65 years, who participated in the organised screening during 2006 were identified in the central database. In addition, all women within the same age category with cytological alterations (ASCUS–CIN3) and a histological identification of CIN2+ within the same time period were recorded. The women in this category were used as historical controls to compare the efficiency of the offered self-sampling method in combination with high-risk HPV testing among women who did not attend a midwife reception for a Pap smear collection. The end point of the study (cohort and control) was a histological identification of CIN2+.

The statistical analysis was performed with Fisher′s exact test.

Results

Of the 3618 women offered self-sampling at home, 50.6% (n = 1830) ordered the device package and 39.4% (n = 1426) performed self-sampling and sent the collected vaginal fluid to our laboratory for high-risk HPV testing. The HPV test was positive in 4.6% (n = 66) of the women and 84.8% (n = 56)of these women accepted the invitation to attend the gynaecological surgery after a mean time of 2.1 months (range 1–7 months) for colposcopy and cervical biopsy. Histological examination of the biopsies showed normal morphology or benign alterations in 25 women, CIN1 in 21 women and CIN2+ in 10 women (Table 1). Ten women did not attend the gynaecological surgery but six of them visited a midwifery reception for a second HPV analysis within 1–3 months after the vaginal fluid collection, corresponding to a total compliance of 93.9%. At that time four women tested negative and two were still HPV positive. These last two women were high-risk HPV negative after attending the midwifery reception for a third HPV test.

Table 1.   Comparison between the study cohort (self-sampling at home and high-risk HPV test) and the control group (Pap-smear screening) of older women with regard to the detection rate of histological CIN2+
 Study cohortControls
  1. *All women with squamous cell alterations ASCUS-CIN3 are included.

  2. **Odds ratio for detection of histological CIN2+ in the study cohort comparison with controls OR = 2.84 (95% CI 1.14–6.77).

Study population3618 
Women ordering self-sampling device1830 (50.6%) 
Women performing self-sampling1426 (39.4%) 
Women performing Pap-smear screening 6048
Number of high-risk HPV positive women66 (4.6%) 
Number of women with squamous cell alterations  268 (4.4%)*
Number of women with CIN2+10 (0.70%)  15 (0.25%)**

During 2006 a total number of 6048 women aged 50–65 years participated in organised Pap smear screening and 4.4% (n = 268) showed cytological squamous alterations (ASCUS–CIN2+). During the same time period the number of identified histological CIN2+ alterations within the same age category was 15, corresponding to 0.25% (15/6048) of the total number of women participating in the screening (Table 1).

The odds ratio for using self-sampled vaginal smear and a high-risk HPV test for detection of CIN2+ when compared with Pap smear for detection of the same lesion was 2.84 (95% CI 1.14–6.77, P = 0.0174).

The specificity of self-sampling at home in combination with HPV testing and Pap smear screening for detection of histological CIN2+ was calculated (Table 2). The specificity of the two screening methods was equal, 95.8–96.0%.

Table 2.   Calculation of specificity of self-sampling of vaginal fluid at home with high-risk HPV testing and of specificity of Pap-smear screening for detection of histological CIN2+ in older women
 CIN2+<CIN2+Total
  1. *Specificity: 1360/1416 = 96.0%.

  2. **Specificity: 5780/6033 = 95.8%.

Self-sampling and HPV testing*
HPV-positive105666
HPV-negative013601360
Total1014161426
Pap-smear screening**
Normal15253268
ASCUS-CIN2+057805780
Total1560336048

Discussion

After the introduction of organised cytological screening the incidence of cervical carcinoma decreased considerably. The benefit of the screening is estimated to be a reduction of the number of women with cervical cancer of at least 50%.13,14 Concomitantly, the age of women with cervical carcinoma has also changed. Previously, the mean age was around 45 years but at present it occurs almost one decade later. Consequently, most women with cervical carcinoma are now postmenopausal. One reason for this difference is that the cytological screening shows a variable sensitivity. In older women only 20% (15) of the efficiency of cytological screening is obtained in comparison with women around 35 years of age. Accordingly, the value of cytological screening of postmenopausal women is considered to be limited.15 Primary high-risk HPV testing has a considerably higher sensitivity for detection of premalignant cervical lesions, and the discrepancy between cytological screening and primary high-risk HPV screening increases with age.15–17

In the present study almost three times more CIN2+ lesions/test were observed in the cohort of women participating in self-sampling and primary high-risk HPV screening compared with the control group of women attending cytological screening. The self-sampling is an alternative intervention to increase compliance in the cervical cancer screening programme. Results from different studies shows that increased attendance increases the number of detected precursor lesions.18

A drawback of primary high-risk HPV screening is thought to be low specificity. However, the proportion of postmenopausal women with a high-risk HPV-positive reaction was almost the same as the proportion of women with abnormal cytology (ASCUS–CIN2+). A total of 4.6% were high-risk HPV positive and 4.4% showed abnormal cytology (ASCUS–CIN2+) in our study. The specificity of Pap smear screening does not vary with age (data not shown) and the number of women with cytological alterations displays relatively small age-related variations, whereas the prevalence of high-risk HPV infections differs in various age groups and is high in young women. This means that the difference in specificity of primary high-risk HPV testing in relation to the specificity of Pap smear screening decreases with age. In a randomised study, the age-specific evaluation of primary HPV screening was assessed. It showed that among women aged 35 years or older, the primary HPV screening tended to have higher specificity than conventional Pap smear screening.17 In the present study primary HPV testing and Pap smear screening showed an equal specificity in women aged 50 years or older. The finding of a higher sensitivity and an equal specificity of primary high-risk HPV screening weakens the arguments for a continuation of cytological screening of postmenopausal women.

Besides the low sensitivity of cytological screening, nonattendance is the most prominent problem with the current organised screening. Around 25% of women with cervical cancer have regularly participated in the screening, but the Pap smears have been normal and 65% of the cancers occur among women who have chosen not to participate. To refine the screening an increased coverage is desired. To obtain this, self-sampling of vaginal fluid in combination with high-risk HPV testing seems attractive. The method is accepted by around 30–40% of the nonattending women and furthermore, they are offered a screening system with a considerably higher sensitivity for detection of premalignant cervical lesions.18–21 The method seems to be especially suited to older women, as this age category has a low prevalence of high-risk HPV infections.22

Disclosure of interests

Erik Wilander is a minority share holder in the company Aprovix AB, marketing Qvintip®. For the other co-authors no conflict of interest is observed.

Contribution to authorship

All four authors made an equal contribution to accomplish the investigation.

Details of ethics approval

The study was evaluated by the local ethics committee (Dnr2004:M-202 and 2009/001).

Funding

The study was supported by the County Council of Uppsala and by the Medical Faculty of Uppsala University.

Ancillary