The performance of Dynamic Spectral Imaging colposcopy depends on indication for referrals

Highlights

• DSI increases the sensitivity of colposcopy, irrespective of most referral reasons.

• If DSI and conventional colposcopy are combined, the sensitivity increases the most.

• DSI colposcopy may enable a baseline sensitivity of the colposcopic exam.

Abstract

Objective

A previous study has shown that Dynamic Spectral Imaging (DSI) colposcopy increases the sensitivity of the colposcopic examination in women referred with abnormal cytology. In this study we have re-analyzed the performance of DSI and conventional colposcopy for new referral conditions and for low-grade cytology referrals versus high-grade cytology referrals.

Method

Data from a previous validation trial was used to assess the performance of DSI in different cytology groups: Women referred with BMD (borderline and mild dyskaryosis) cytology and women referred with > BMD cytology either hrHPV positive or negative were separately analyzed. Furthermore, we tried to assess the clinical performance by appropriate filtering of patients to replicate two different referral strategies.

Results

The sensitivity of DSI and conventional colposcopy to detect CIN2 + lesions in women referred with BMD cytology is 82% and 44% respectively (p = 0.001) and in the > BMD group 77% and 64% respectively (p = 0.24). If the two techniques are combined the sensitivity is 85%. When the conditions of new screening strategies are applied DSI colposcopy has a higher sensitivity to detect CIN2 + than conventional colposcopy. Findings are similar when CIN3 + is used as a threshold.

Conclusion

We found that in most cases DSI colposcopy has a higher sensitivity than conventional colposcopy, even when referral criteria are changed. Unlike conventional colposcopy, the sensitivity of colposcopy with DSI in low-grade cytology referrals was found similar to the sensitivity in high-grade cytology referrals. This suggests that a baseline colposcopy sensitivity may be possible with the adjunctive use of the DSI map, irrespective of referral cytology.

Introduction

Colposcopy is a visual technique, used to examine the uterine cervix for (pre)malignant disease and direct the collection of biopsy samples. Conventional colposcopy has several limitations; firstly, the prediction of disease is related to the skill and experience of the colposcopist [1]. Inter-observer agreement is only moderate, with levels of agreement increasing as cervical lesions become more severe [1]. Furthermore, the choice of biopsy site is subjective and is hampered by the suboptimal correlation between visual changes and disease severity [2], [3]. These restrictions result in a modest sensitivity of approximately 55% to distinguish high-grade from low-grade lesions [4], [5], [6], [7], [8].

Colposcopy with Dynamic Spectral Imaging (DSI, DySIS digital colposcope, DySIS Medical Ltd, Livingston, UK), has a higher sensitivity to detect high-grade premalignant cervical disease (Cervical Intraepithelial Neoplasia grade 2/3 or worse; CIN2 +) than conventional colposcopy [9], [10]. Soutter et al. demonstrated that on a population referred for colposcopy with abnormal cytology or symptoms, the DSI map had a significantly higher sensitivity than conventional colposcopy to identify patients with CIN2 + lesions [10]. In our validation trial we have shown that when DSI is used adjunctively with conventional colposcopy, the sensitivity of the examination to detect patients with CIN2 + lesions is almost 90% [9]. However, this trial included women referred for colposcopy according to the Dutch national guidelines in 2008. HrHPV-testing was not incorporated in the referral strategy which included both women with borderline or mild dyskaryosis (BMD), and women with worse than borderline and mild dyskaryosis (> BMD) cytology. BMD corresponds to ASC-US/ASC-H/LSIL and > BMD equals HSIL [11]. However, it is known that the sensitivity of the colposcopic exam is highly dependent of referral cytology. If the referral cytology is more severe, the sensitivity of the colposcopic exam to detect high-grade lesions is higher [4].

Furthermore, since 2008 screening and referral guidelines have changed, both in the Netherlands and internationally as a result of the clinical efficacy and potential cost savings expected by introducing hrHPV testing [12], [13], [14], [15], [16]. In the Netherlands we are changing our screening program to hrHPV-testing as the primary screening test. In this strategy (which is not fully implemented yet), cytology is only used to triage women that have been tested positive for hrHPV [17]. Current screening strategies use hrHPV-testing as a reflex test to BMD cytology (e.g. UK [18] and Sweden [16]), or ASC-US cytology (e.g. USA [19] and the Netherlands), whereas all > BMD cytology is directly referred to colposcopy.

The purpose of this study was twofold: Firstly we re-analyzed the performance of DSI and conventional colposcopy to determine the difference between low-grade cytology (BMD) referrals and high-grade cytology (> BMD) referrals. Secondly we also re-analyzed the performance of DSI and conventional colposcopy for two new referral strategies; hrHPV-testing as primary screening test and reflex hrHPV-testing in BMD cytology.