Infection with oncogenic human papillomavirus (HPV) is the major risk factor in the aetiology of cervical cancer. In a previous study of invasive cervical cancers collected from 22 countries (the International Biological Study on Cervical Cancer, IBSCC), however, the PCR assay used failed to detect HPV DNA in 7% of samples. The current study re-examined these so-called HPV-negative samples, as well as a proportion of the originally positive samples, using a more stringent procedure to ensure the presence of carcinoma cells within the material used for PCR. In addition, three different PCR assays targeting different open reading frames were used, to avoid misclassifying as negative samples in which integration of HPV DNA had led to disruption of the PCR primer sequences or loss of the HPV L1 open reading frame, the target of the PCR assay used in the original study. Furthermore, sera from the patients originally classified as HPV-negative were assayed for antibodies against viral-like particles (VLPs) and E6 and E7 proteins of HPV 16, which accounts for about 50% of HPV-positive cervical cancers world-wide. Of those serum samples tested, antibodies to at least one HPV 16 protein were detected in a similar proportion of those originally classified as HPV-negative or -positive: 56% and 67%, respectively. There was no significant difference between the two groups in the proportion of antibodies reactive to VLPs, E6 or E7. After excluding histologically inadequate samples (87%), only 6% of those initially classified as HPV-negative remained negative to all the PCR assays used for retesting. Thus the true incidence of HPV-positive samples in the IBSCC is 99.7%. Most of the HPV-negative samples in the earlier study proved to have been misclassified since a more stringent testing procedure revealed them to be HPV-positive. The similarity of the serum antibody profiles from patients with cancers originally classified as HPV-positive and –negative indicates that a significant proportion of the latter were in fact HPV 16- associated. The extreme rarity of HPV-negative cancers reinforces the rationale for HPV testing in addition to, or even instead of, cervical cytology in routine cervical screening.

1. Human Papillomavirus and Cervical Cancer: Latest Publications Volume 1 2000
HUMAN PAPILLOMAVIRUS IS A NECESSARY CAUSE OF INVASIVE
CERVICAL CANCER WORLD-WIDE
Jan M.M. Walboomers1, Marcel V. Jacobs1, Michele M. Manos2, F. Xavier Bosch3, J. Alain Kummer1,
Keerti V. Shah2, Peter J.F. Snijders1, Julian Peto4, Chris J.L.M. Meijer1 and Nubia Munoz5
1
Department of Pathology, University Hospital Vrije Universiteit, Amsterdam, the Netherlands
2
Department of Molecular Microbiology and Immunology, Johns Hopkins University, Baltimore, MD, USA
3
Institute Catala d’Oncologia, Barcelona, Spain
4
Institute of Cancer Research, Belmont, Surrey, UK
5
Unit of Field and Intervention Studies, IARC, Lyon, France
Journal of Pathology 189: 12-19 (1999)
Main points:
• Virtually all cervical cancers (99.7%) contain HPV DNA.
• HPV testing should be used in combination with, or even instead of, cytology in routine screening programmes.
Abstract:
Infection with oncogenic human papillomavirus (HPV) is the major risk factor in the aetiology of cervical cancer. In a
previous study of invasive cervical cancers collected from 22 countries (the International Biological Study on Cervical
Cancer, IBSCC), however, the PCR assay used failed to detect HPV DNA in 7% of samples. The current study
re-examined these so-called HPV-negative samples, as well as a proportion of the originally positive samples, using a
more stringent procedure to ensure the presence of carcinoma cells within the material used for PCR. In addition,
three different PCR assays targeting different open reading frames were used, to avoid misclassifying as negative
samples in which integration of HPV DNA had led to disruption of the PCR primer sequences or loss of the HPV L1
open reading frame, the target of the PCR assay used in the original study. Furthermore, sera from the patients
originally classified as HPV-negative were assayed for antibodies against viral-like particles (VLPs) and E6 and E7
proteins of HPV 16, which accounts for about 50% of HPV-positive cervical cancers world-wide.
Of those serum samples tested, antibodies to at least one HPV 16 protein were detected in a similar proportion of
those originally classified as HPV-negative or -positive: 56% and 67%, respectively. There was no significant difference
between the two groups in the proportion of antibodies reactive to VLPs, E6 or E7. After excluding histologically
inadequate samples (87%), only 6% of those initially classified as HPV-negative remained negative to all the PCR
assays used for retesting. Thus the true incidence of HPV-positive samples in the IBSCC is 99.7%.
Most of the HPV-negative samples in the earlier study proved to have been misclassified since a more stringent
testing procedure revealed them to be HPV-positive. The similarity of the serum antibody profiles from patients with
cancers originally classified as HPV-positive and –negative indicates that a significant proportion of the latter were in
fact HPV 16- associated. The extreme rarity of HPV-negative cancers reinforces the rationale for HPV testing in
addition to, or even instead of, cervical cytology in routine cervical screening.
1