Maria Hortlund1, Karin Sundström1, Helena Lamin2, Anders Hjerpe1, Joakim Dillner3. 1. Department of Laboratory Medicine, Karolinska Institutet, Sweden. 2. Department of Laboratory Medicine, Karolinska University Hospital, Sweden. 3. Department of Laboratory Medicine, Karolinska Institutet, Sweden. Electronic address: joakim.dillner@ki.se.
Abstract
BACKGROUND: As primary HPV screening programs are rolled out, methods are needed for routine quality assurance of HPV laboratory analyzes. OBJECTIVE: To explore the use of similar design for audit as currently used in cytology-based screening, to estimate the clinical sensitivity to identify women at risk for CIN 3 or worse (CIN3+). STUDY DESIGN: Population-based cohort study conducted within the cervical screening program in Stockholm, Sweden, in 2011-2012. All women with histopathologically confirmed CIN3+ in the following two years were identified by registry analysis. Primary HPV and cytology screening results were collected. For women who had not been HPV tested, biobanked cytology samples were HPV-tested. If the original HPV result had been negative, the sample and subsequent biopsies were analyzed with broad HPV typing (general primer PCR and Luminex). RESULTS: 154 women had a biobanked prediagnostic cytology sample taken up to 2 years before a histopathologically confirmed CIN3+. The high-risk HPV-positivity was 97% (148/154 women), whereas 143/154 (94%) women had had a cytological abnormality. Among the six HPV-negative samples, one sample was HPV 33 positive in repeat testing whereas the other five cases were HPV-negative also on repeat testing, but HPV-positive in the subsequent tumor tissue. CONCLUSIONS: A sensitivity of the HPV test that is higher than the sensitivity of cytology suggests adequate quality of the testing. Regular audits of clinical sensitivity, similar to those of cytology-based screening, should be used also in HPV-based screening programs, in order to continuously monitor the performance of the analyzes.
BACKGROUND: As primary HPV screening programs are rolled out, methods are needed for routine quality assurance of HPV laboratory analyzes. OBJECTIVE: To explore the use of similar design for audit as currently used in cytology-based screening, to estimate the clinical sensitivity to identify women at risk for CIN 3 or worse (CIN3+). STUDY DESIGN: Population-based cohort study conducted within the cervical screening program in Stockholm, Sweden, in 2011-2012. All women with histopathologically confirmed CIN3+ in the following two years were identified by registry analysis. Primary HPV and cytology screening results were collected. For women who had not been HPV tested, biobanked cytology samples were HPV-tested. If the original HPV result had been negative, the sample and subsequent biopsies were analyzed with broad HPV typing (general primer PCR and Luminex). RESULTS: 154 women had a biobanked prediagnostic cytology sample taken up to 2 years before a histopathologically confirmed CIN3+. The high-risk HPV-positivity was 97% (148/154 women), whereas 143/154 (94%) women had had a cytological abnormality. Among the six HPV-negative samples, one sample was HPV 33 positive in repeat testing whereas the other five cases were HPV-negative also on repeat testing, but HPV-positive in the subsequent tumor tissue. CONCLUSIONS: A sensitivity of the HPV test that is higher than the sensitivity of cytology suggests adequate quality of the testing. Regular audits of clinical sensitivity, similar to those of cytology-based screening, should be used also in HPV-based screening programs, in order to continuously monitor the performance of the analyzes.