The use of biomarkers and HPV genotyping to improve diagnostic accuracy in women with a transformation zone type 3

Abstract

Background: Twenty percent of women referred to colposcopy have a type 3 transformation zone-where colposcopic assessment for high-grade dysplasia (CIN2+) is not possible. This study examines the effectiveness of HPV biomarkers and genotyping in combination with techniques that sample an endocervical TZ.

Methods: A prospective diagnostic accuracy study. Women booked for large-loop excision (LLETZ) with squamous dyskaryosis, high-risk HPV and a TZ3 were recruited. Immediately prior to LLETZ samples were collected for p16/Ki-67 dual-stained cytology, HPV genotyping and H&E, p16- and Ki-67-stained endocervical curettings.

Results: In women with low-grade screening (n = 64), 35.9% had CIN2+; dual-stained cytology had the greatest effect on the PPV of routine screening (76.1% vs 35.9%) and perfectly predicted the absence of CIN2+. In women with a high-grade screening result (n = 37); 75.6% had CIN2+ and dual-stained curettings improved the PPV (96.5 vs 75.6%).

Conclusions: With high-grade screening and a TZ3, LLETZ appears safest as three quarters have CIN2+ . Women with low-grade screening and a TZ3 have a twofold increased risk of CIN2+ when compared to women where the TZ is visible. The use of dual-stained cytology may help identify those women who can be safely offered surveillance and those who require treatment.

Fig. 1. Flowchart of study recruitment.

Incorporates the number of women who had a LLETZ treatment within the department over the recruitment period, those eligible for participation in the study, total recruited, number of adequate samples and complete datasets.

Fig. 2. Endocervical curettings with H&E, Ki-67 and p16 immununostains.

Referral and index cytology reported as BNC. HPV 33 & 35 on genotyping. Dual-stain positive. Curettings fragmented. CIN of indefinable grade on H&E (a), full-thickness Ki-67 staining (b), strongly stained p16 (c). The final diagnosis for the index curettings was CIN2+. LLETZ reported as CIN3.

Fig. 3. Dual-staining (p16/Ki-67) of the cervical screening cytology samples.

Referral and index cytology reported as BNC; increased nuclei:cytoplasmic ratio but clumping of the cells reduced differentiation of reactive cells from dyskaryotic on the index cytology (a). HPV 16 and 33 on genotyping. Dual-staining was reported as positive (b). CIN2 was reported in the LLETZ histology.