Rapid and sensitive detection of physical status of human papillomavirus type 16 DNA by quantitative real-time PCR

Integrated human papillomavirus types 52 and 58 are infrequently found in cervical cancer, and high viral loads predict risk of cervical cancer

OBJECTIVE

The aim of this prospective study was to analyze whether integration or high viral loads of human papillomavirus (HPV) is essential for malignant transformation of HPV types 52 and 58 as well as types 16 and 18.

METHODS

Cervical swabs from 178 consecutive patients, including 81 with invasive cervical cancers and 97 with cervical intraepithelial neoplasias (CIN) II-III, were collected and examined to determine the physical status and viral load of HPV types 16, 18, 52 and 58 DNA using genechip and real-time PCR (polymerase chain reaction) analysis.

RESULTS

In cervical cancer patients, the integrated form of HPV 52 and 58 DNA was found in 25.0% and 12.5% of swabs, respectively; while HPV16 and 18 DNA was found in 82.6% and 100% of swabs, respectively (P < 0.01, for pair-wise comparison of types 16, 18 versus types 52, 58). The viral loads reflected by the amount of E6 for HPV 16, 18, or 52 were significantly increased in invasive cervical cancer compared to CINII-III (P = 0.022 for type 16, P = 0.003 for type18, and P = 0.001 for type 52, respectively). Area under the receiver operating characteristic (ROC) curve for cervical cancer versus CIN II-III was 73.8%, 92.9%, and 88.5% for HPV 16, 18, and 52, respectively, indicating that real-time PCR had good diagnostic value in differentiating cervical cancer from CIN II-III.

CONCLUSIONS

Infrequent integration of HPV 52 and 58 DNA in cervical cancer suggests that it is not prerequisite for progression to cervical cancer. High viral loads (E6) of HPV 16, 18, and 52 DNA may be predictive of the transition of CIN II-III to cervical cancer. Our results indicate that both viral DNA physical status and viral loads of HPV are important factors in the carcinogenesis of different HPV types.

Early integration of high copy HPV16 detectable in women with normal and low grade cervical cytology and histology

BACKGROUND

Integration of human papillomavirus (HPV) DNA has been considered a late event in cervical carcinogenesis. However, integrated forms of HPV were recently detected in cancer precursor lesions using a new real time polymerase chain reaction (PCR) to detect the deletions at the 3362-3443 region of HPV16 E2 OBJECTIVE: To study the frequency of HPV16 DNA integration in cervical lesions and compare the sensitivity of an additional upstream region of the E2 ORF (2962-3138) in detecting HPV integration.

METHODS

Using the TaqMan based PCR, HPV16 positive DNA samples were analysed in 164 cervical scrapings from women participating in a multicentre screening trial. Biopsy confirmation was available in 62 cases.

RESULTS

Primers targeting the 3362-3443 region detected the majority of E2 deletions. In only 23% of the samples was the E2 upstream region equal or better target than the 3362-3443 region. Mixed (episomal/integrated) pattern was the most prevalent physical state of HPV16, also present in PAP smears with normal morphology. Pure integrated form was most prevalent in HSIL and cancer lesions, but also detectable in low grade abnormalities (NSIL, ASC-US, LSIL). Women with only integrated HPV16 were almost 10 years older than those with episomal HPV16. Viral load of integrated HPV16 was related to cytological abnormality (p = 0.003) but not to histology.

CONCLUSIONS

Integrated HPV16 is present in low grade cervical lesions, mostly mixed with the episomal form. Women with the pure integrated form of HPV16 are older than those with the other forms.

High level of correlation of human papillomavirus-16 DNA viral load estimates generated by three real-time PCR assays applied on genital specimens

Human papillomavirus-16 (HPV-16) viral load could be a biomarker predictive of the presence of high-grade cervical lesions. Recently, several real-time PCR assays have been developed to accurately measure HPV-16 viral load. However, results from various reports using these assays cannot be compared because interassay test correlation has not been documented. The variability of HPV-16 DNA quantitation was assessed by comparing three real-time PCR assays (HPV-16 L1, HPV-16 E6, and HPV-16 E6 PG) applied on 144 genital samples (125 cervicovaginal lavages and 19 specimens collected using vaginal tampons) obtained from 84 women (66 HIV seropositive and 18 HIV seronegative). Correlation was greater between the HPV-16 E6 assays [correlation coefficient (rho) = 0.92] than between each E6 assay and HPV-16 L1 assay (rho = 0.83 and 0.84, respectively). The median HPV-16 copies measured by HPV-16 E6 PG (14,609 HPV-16 copies/2 muL sample) and HPV-16 E6 (18,846 HPV-16 copies/2 muL) were similar (P = 0.27) but were both greater than the median HPV-16 copies measured with the L1 assay (4,124 HPV-16 copies/2 muL; P < 0.001). Correlations between HPV-16 E6 assays were similar for samples containing non-European (rho = 0.93) or European (rho = 0.95) variants. However, the correlation between HPV-16 L1 and HPV-16 E6 PG or HPV-16 E6 was lower for specimens containing non-European variants (rho = 0.80 and 0.76, respectively) compared with specimens containing European variants (rho > 0.85). HPV-16 DNA quantity estimated with the three assays was comparable although lower with the HPV-16 L1 assay. The level of correlation depended on viral polymorphism, viral load, and cervical disease status.

Dynamics of HPV16 DNA load reflect the natural history of cervical HPV-associated lesions

BACKGROUND

High burden of high risk human papillomavirus (HR HPV) has been shown to be predictive for the development of high grade cervical lesions and invasive cancers. However, low viral load cannot inevitably exclude progression towards cervical diseases. Moreover, few studies addressed whether viral load could predict infection clearance.

OBJECTIVES

We carried out a retrospective study to analyze the variations of HPV16 load over time as a predictive marker of clinical outcome.

STUDY DESIGN

The population consisted of 38 women who were found HR HPV positive by HCII test at study entry. Among them, 13 had developed a CIN2/3 (cases) and 25 had a negative HCII test and a normal cytology (controls) at study exit. The HPV16 DNA loads were quantified in 132 longitudinal cervical samples using quantitative real-time PCR.

RESULTS

At study entry, the median of HPV16 load was not statistically different between controls and cases. However, when using a cut-off value of 200 copies/10(3) cells, the rate of cumulative incidence of CIN2/3 at 18 months increased from 14% in women with a load<or=200 copies/10(3) cells to 48% in women with a load>200 copies/10(3) cells. The longitudinal analysis performed on follow-up samples showed that in cases the progression to CIN2/3 was linked to HPV16 burden increasing over time, whereas in controls a decrease of at least 1 log HPV16 DNA load was observed over>or=2 time points.

CONCLUSIONS

These results show that kinetics of HPV load, rather than a single HPV detection, might be more reliable to estimate whether a HPV infection will progress or be cleared.

Human papillomavirus (HPV) transcripts in malignant inverted papilloma are from integrated HPV DNA

OBJECTIVES

The objectives of the study were to detect human papillomavirus (HPV) sequences in nasal inverted papilloma (IP) lesions and to determine whether HPV is involved in the progression of IP to sinonasal squamous cell carcinoma (SCC).

STUDY DESIGN

A retrospective study was performed on 14 patients diagnosed with IP within the last 12 years. Three of these 14 patients developed SCC.

METHODS

Eighteen formalin-fixed, paraffin-embedded tissue blocks were obtained for these 14 patients. After DNA extraction, polymerase chain reaction (PCR) was performed, followed by hybridization using HPV 6, 11, 16, 18, 31, 33, 35, 45, and 52 specific DNA probes, in an attempt to identify HPV type in each specimen. After RNA extraction, the integration status of the HPV genome was evaluated based on the relative abundance of E7 and E5 viral transcripts, assessed by quantitative real-time PCR.

RESULTS

HPV sequences were detected in samples from 3 of the 14 patients with IP. Of the three patients with SCC, HPV sequences were detected in two patients, whereas one patient was negative for the oligoprobes tested. Of the 11 patients diagnosed only with IP, 1 patient was positive for HPV DNA (HPV type 11). This difference in HPV positivity between IP and SCC was not statistically significant (P = .09, Fisher's Exact test, two tailed). Viral transcripts were detected in both patients with SSC who were HPV positive. Because HPV early transcripts are polycistronic, loss of 3' transcript sequences (E5) and retention of 5' sequences (E7) indicates integration. One of the SSC containing HPV 18 sequences showed a E7/E5 ratio of 776:1. The other SSC showed E7 transcripts and an absence of E5 transcripts

CONCLUSION

HPV transcripts were present in SCC positive for HPV, and the relative level of E7 to E5 transcripts indicates integration of the viral genome. These findings are suggestive of HPV having an active role in the lesion. More extensive studies are needed to determine the exact role of HPV in IP and progression to SCC.

Comparison between in situ hybridization and real-time PCR technique as a means of detecting the integrated form of human papillomavirus 16 in cervical neoplasia

Integration of the human papillomavirus (HPV) genome is thought to be one of the causes of cancer progression. However, there is controversy concerning the physical status of HPV 16 in premalignant cervical lesions, and there have been no reports on the concordance between detection of the integrated form of HPV16 by real-time PCR and by in situ hybridization. We investigated specimens of cervical intraepithelial neoplasia (CIN) and invasive carcinomas for the physical status of HPV 16 by real-time PCR and in situ hybridization. The presence of the integrated form was detected by both real-time PCR and in situ hybridization in zero of four cases of CIN1, three of six cases of CIN2, nine of 27 cases of CIN3, and two of six cases of invasive carcinomas. Integrated HPV 16 was present in some premalignant lesions but was not always present in carcinomas. The concordance rate between the two methods for the detection of the presence of the integrated form was 37 of 43 (86%) cases. Real-time PCR and in situ hybridization were found to be complementary and convenient techniques for determining the physical status of the HPV genome. We conclude that a combination of both methods is a more reliable means of assessing the physical status of the HPV genome in cervical neoplasia.

High levels of HPV-16 DNA are associated with high-grade cervical lesions in women at risk or infected with HIV

OBJECTIVE

To examine associations between levels of episomal and integrated human papillomavirus (HPV) 16 DNA and the grade of cervical disease.

DESIGN

Cross-sectional data were obtained from a cohort of women with and without HIV infection and with high-risk sexual behaviour.

METHODS

Episomal and integrated HPV-16 DNA loads were measured in cervicovaginal lavages collected from 75 women (58 HIV seropositive, 17 HIV seronegative) using real-time polymerase chain reaction assays, controlling for cell content and the presence of inhibitors.

RESULTS

HPV-16 viral loads were significantly higher in women with high-grade squamous intraepithelial lesions (n = 6) than in women with normal cytology (n = 44), whether total (10(8.28) versus 10(5.10) HPV-16 DNA copies/microg DNA), episomal (10(7.99) versus 10(4.61)) or integrated (10(7.95) versus 10(4.77)) HPV-16 viral loads were measured (P < 0.02 for each comparison). Thirty-nine women had colposcopy [11 normal cervix, 16 cervical intraepithelial neoplasia (CIN) 1, six CIN 2, six CIN 3] and 24 additional women had three consecutive normal cytology smears. Controlling for age, race, CD4 cell count and HIV status, total (OR 3.5, 95% CI 1.2-10.4; P = 0.02), episomal (OR 2.9, 95% CI 1.2-7.4; P = 0.02,) and integrated (OR 1.6, 95% CI 1-2.6; P = 0.05) HPV-16 DNA loads were significantly associated with CIN 2,3, but the differences between CIN 1 and CIN 2,3 were not significant (P > 0.06). A greater amount of cellular DNA was collected from women with CIN 2,3 (P = 0.007).

CONCLUSION

Higher HPV-16 DNA loads are associated with cervical lesions detected by either histology or cytology. No additional information is gained by measuring integrated or episomal over total HPV-16 DNA loads.

Physical status of HPV-16 in esophageal squamous cell carcinoma

BACKGROUND

Infection with high-risk human papillomavirus (HPV) has been implicated as one of the risk factors of esophageal squamous cell carcinoma (ESCC). Integration of viral DNA into host genome is essential for carcinogenesis since it promotes disruption of the HPV E2 gene, leading to abnormal expression of E6 and E7 oncoproteins.

OBJECTIVES AND STUDY DESIGN

To investigate the viral integration status of HPV-16 infection in ESCC, 35 HPV-positive ESCC specimens collected from Chinese patients were subject to real-time quantitative PCR for determination of physical status of HPV-16 by analyzing the ratios of E2 to E6 genes.

RESULTS

Our results showed that only 8.6% (3/35) of the HPV-16 positive specimens harbored exclusively the episomal form (i.e. E2/E6 ratio > or = 1), whereas the remaining 91.4% contained either only the integrated form (5.7%, with E2/E6 ratio = 0) or a mixture of episomal and integrated forms of viral molecules (85.7%, with E2/E6 ratios > 0 but < 1). Amongst the 30 cancer specimens carrying mixed integrated and episomal forms, 28 had E2/integrated E6 ratios of less than 1, indicating a predominance of integrated form of viral genes in these lesions.

CONCLUSION

Our finding of frequent integration of viral DNA in the host genome suggests that integration HPV-16 is common in ESCC from Chinese patients and implies that HPV infection may play a role in the pathogenesis of ESCC.

Folate Is Associated with the Natural History of High-Risk Human Papillomaviruses

Several micronutrients have been implicated in cervical carcinogenesis. However, their mode of action is still a matter of speculation. In particular, it is unclear whether certain nutrients reduce the probability of acquiring high-risk human papillomavirus (HPV) or whether they facilitate the clearance of high-risk HPV. We conducted a 24-month prospective follow-up study to test the hypothesis that systemic concentrations of folate are associated with the occurrence and duration of high-risk HPV infections after controlling for other micronutrients (vitamins B(12), A, E, and C, total carotene) and known risk factors for high-risk HPV infections and cervical cancer. Circulating concentrations of these micronutrients and risk factors for cervical cancer were determined in a cohort of 345 women who were at risk of developing cervical intraepithelial neoplasia. Using the hybrid capture 2 (HC-2) assay, high-risk HPV status was evaluated at 6-month intervals up to 24 months. All women had at least three consecutive visit high-risk HPV test results. Higher folate status was inversely associated with becoming HC-2 test-positive [odds ratio (OR): 0.27; 95% confidence interval (CI), 0.08-0.91; P = 0.04]. Women with higher folate status were significantly less likely to be repeatedly HC-2 test-positive (OR: 0.33; 95% CI, 0.13-0.86; P = 0.02) and more likely to become test-negative during the study (OR: 2.50; 95% CI, 1.18-5.30; P = 0.02). To our knowledge, this is the first long-term prospective follow-up study reporting an independent protective role of higher folate status on several aspects of the natural history of high-risk HPV after controlling for known risk factors and other micronutrients. Improving folate status in subjects at risk of getting infected or already infected with high-risk HPV may have a beneficial impact in the prevention of cervical cancer.

E2 sequence variations of HPV 16 among patients with cervical neoplasia seen in the Indian subcontinent

OBJECTIVES

Specific nucleotide variations in the E2 DNA sequence were looked for in samples with an intact human papillomavirus (HPV) 16 episomal E2 DNA.

METHODS

Ninety-two women, 76 with invasive cervical carcinoma and 16 with cervical intraepithelial neoplasia (CIN) were recruited. HPV DNA typing was performed by polymerase chain reaction (PCR) based restriction fragment length polymorphism (RFLP). Intact episomal E2 DNA of HPV 16 was detected by PCR. Important nucleotide variations in samples with amplifiable E2 DNA were detected by RFLP. Nucleotide sequencing was performed on representative samples to confirm RFLP findings.

RESULTS

A total of 89 (96.7%) women were positive for HPV DNA. Of these, 56 (63%) were positive for HPV 16, and of these, 38 (68%) were positive for intact episomal HPV 16 E2 DNA while 18 (32%) were negative. Samples with intact episomal HPV 16 E2 DNA sequences were grouped into four different digestion profiles I to IV based on RFLP patterns. Digestion patterns revealed absence of any sequence variations in samples with digestion profile I and presence of a 2983 A-G variation in those with profile II. Samples with digestion profiles III and IV revealed three variations in the hinge region (3516 C-A, 3538 A-C, 3566 T-G) and two in the DNA binding domain (3684 C-A, 3694 T-A) of the E2 sequence. Sequencing performed on representative samples confirmed RFLP findings.

CONCLUSIONS

PCR-RFLP helped in the identification of important HPV 16 E2 sequence variations, circumventing the need for sequencing. The presence of the nucleotide variations in positions that could alter the biological and immunological functions of the E2 protein combined with its increased occurrence in this study bring out the importance of these variations.

Human papillomavirus oncogenic expression in the dysplastic portio; an investigation of biopsies from 190 cervical cones

In this study, we investigated the presence of E6/E7 transcripts of seven common high-risk human papillomavirus (HPV) types in 190 cervical biopsies. The RNA-based real-time nucleic acid sequence-based amplification assay (NASBA) and type-specific PCR, both detecting HPV 16, 18, 31, 33, 45, 52, and 58, as well as consensus PCR, were performed on all 190 biopsies. High accordance between type-specific and consensus PCR confirms that the HPV types included in this study are the most common types present in cervical dysplasia. Furthermore, we see a clear increase in the incidence of HPV, both DNA and RNA, along with the histological severity of dysplasia. HPV RNA was detected in all but two PCR-positive cases, confirming that the virus exerts E6/E7 mRNA expression in cases of high-grade dysplasia. Out of 19 women given a normal or borderline diagnosis at conisation, only four were found HPV positive, which may suggest that unnecessary conisations can possibly be reduced by introducing HPV testing into the preoperative routine assessment.

Real-time PCR assays using internal controls for quantitation of HPV-16 and β-globin DNA in cervicovaginal lavages

High-risk human papillomavirus 16 (HPV-16) DNA viral load has been measured with real-time PCR assays by amplifying HPV-16 and a human gene. However, these assays have not used internal controls (ICs) to screen for the presence of inhibitors contained in samples. To quantitate HPV-16 DNA and cell content with real-time PCR, ICs for HPV-16 DNA and beta-globin were synthesised and used to control for inhibition. The assays were sensitive and linear over 5 logs. Good reproducibility was achieved with inter-run coefficients of variation of 23% (10(2) HPV-16 copies), 12% (10(4) HPV-16 copies), 17% (274 beta-globin DNA copies) and 7% (27,400 beta-globin DNA copies). Samples containing 56,800,000, 306,000, 18,000, and 4,070 HPV-16 copies/microg of cellular DNA were tested blindly and estimated to contain 48,800,000, 479,000, 20,300, and 6,620 HPV-16 copies/microg of DNA (mean ratio of measured to expected viral load of 1.27+/-0.32). Inhibition of amplification of HPV-16 and beta-globin ICs by six samples known to contain PCR inhibitors was variable: four inhibited both ICs while two inhibited only the HPV-16 IC. The use of internal controls with real-time PCR for HPV-16 quantitation allows to screen for the presence of inhibitors that do not affect equally primer-driven genomic amplification.

Prevalence of selective inhibition of HPV-16 DNA amplification in cervicovaginal lavages

HPV-16 viral load has been assessed with real-time PCR assays by measuring HPV-16 DNA and a human gene in genital samples. HPV-16 viral load measurements are thus based on the inference that inhibitors contained in samples will equally impede amplification of DNA sequences from HPV-16 and human DNA. We have previously shown that sample lysates can inhibit amplification of HPV-16 but not beta-globin DNA. In the current study, cervicovaginal lavages lysates considered adequate for PCR analysis by a qualitative beta-globin PCR test, were screened for the presence of inhibitors using internal controls (IC) for HPV-16 DNA and beta-globin in real-time PCR assays. Of 150 lysates screened with both ICs, 12 (8%) contained inhibitors. Inhibition of amplification of both ICs was demonstrated in four of these specimens. In eight lysates, amplification of HPV-16 IC only was impeded. Six (50%) of these 12 lysates tested positive for HPV-16 DNA despite the presence of PCR inhibitors. The HPV-16 viral load increased significantly after dilution of 11 of 12 lysates, demonstrating the presence of inhibitors in the undiluted lysate. Nine (90%) of 10 samples with inhibitors that were tested after dilution did not demonstrate inhibitory activity. The use of internal controls in real-time PCR is clearly essential to determine HPV viral loads since the effect of inhibitors on primer-driven genomic amplification is variable.

Prevalence and physical status of human papillomavirus in squamous cell carcinomas of the head and neck

Fresh-frozen biopsies were obtained from 61 patients at diagnosis of squamous cell carcinoma of the head and neck (HNSCC) for study of the prevalence and physical status of human papillomavirus (HPV) DNA. The frequency of HPV DNA and genotypes were determined by SPF10 PCR screening with a general probe hybridization and INNO-LiPA HPV genotyping assay. In addition, a single-phase PCR with primers FAP 59/64 and a nested PCR with primers CP 65/70 and CP 66/69 served to detect particularly cutaneous HPV types. By the sensitive SPF10 PCR and INNO-LiPA assay, 37 of 61 (61%) samples were positive for HPV. HPV-16 was the most frequently detected type (31 of 37, 84%). Multiple infections were found in 8 of 37 (22%) of the HPV-positive samples, and co-infection by HPV-16 and HPV-33 was predominant. No cutaneous HPV types were detected. Patients with HPV-positive tumors had similar prognosis as those with HPV-negative ones. Real-time PCR analysis of the HPV-16 positive samples indicated the presence of integrated (11 of 23, 48%), episomal (8 of 23, 35%) and mixed forms (4 of 23, 17%) of HPV DNA. The viral load of HPV DNA exhibited large variation. The median copy numbers of E6 DNA in tonsillar specimens were approximately 80,000 times higher than that in nontonsillar HNSCC ones. Patients with episomal viral DNA were more frequently found to have large (T3-T4) tumors at diagnosis than were those with integrated or mixed forms.

Monoclonal expansion with integration of high-risk type human papillomaviruses is an initial step for cervical carcinogenesis: association of clonal status and human papillomavirus infection with clinical outcome in cervical intraepithelial neoplasia

To define the natural history of cervical intraepithelial neoplasia (CIN) as related to clonal status, we evaluated 20 cases of CIN1 and 18 cases of CIN2 that had been clinically followed for 7 to 48 months at Osaka University Hospital. These included 10 cases that progressed, 15 cases that persisted, and 13 cases that regressed. We analyzed the clonal status of each case by analysis of the pattern of X-chromosomal inactivation. Human papillomavirus (HPV) infection was detected by PCR-RFLP analysis. CINs that are monoclonal or infected by high-risk HPVs are more likely to progress or persist than cases that are polyclonal or negative for high-risk HPVs (p = 0.009 for monoclonal vs polyclonal, p = 0.024 for high-risk HPV positive vs negative p = 0.024). Eighteen (90%) of 20 monoclonal, high-risk HPV-associated CINs progressed or persisted, whereas 9 (60%) of 15 polyclonal or high-risk HPV-negative CINs regressed. Therefore, the combination of clonality status and high-risk type HPV infection was significantly correlated with clinical outcome (p = 0.003). The physical status of the HPV genome was evaluated in 17 cases of HPV-16 positive CINs by real-time PCR. Of those, the HPV viral genome was present in both episomal and integrated forms in 14 CINs (84%), and 12 of these cases (86%) were monoclonal in composition. By contrast, all three CINs in which the HPV genome was present in episomal form were polyclonal. In one CIN1 that was polyclonal, HPV-16 was originally present in episomal form but after 24 months, the patient developed a monoclonal CIN3 in which the HPV-16 genome was present in mixed form. These results may imply that HPV viral integration into the host genomic DNA is associated with progression from polyclonal to monoclonal status in CIN. These events may play a fundamental role in the progression from low-grade to higher grade dysplasia of the cervical mucosa.

The Epidemiology of Cervical Cancer

Cervical cancer is one of the most common neoplastic diseases affecting women, with a combined worldwide incidence of almost half a million new cases annually, second only to breast cancer. Basic and epidemiologic research conducted during the past 15-20 years have provided overwhelming evidence for an etiologic role for infection with certain types of sexually-transmitted human papillomavirus (HPV) as the primary cause of cervical cancer. The relative risks of cervical cancer following HPV infection as ascertained in case-control and cohort studies are among the highest in cancer epidemiology. The available evidence indicates that the HPV-cervical cancer association satisfies all relevant causal criteria for public health action. Other cervical cancer risk factors, such as smoking, parity, use of oral contraceptives, diet, other infections, and host susceptibility traits must be understood in the context of mediation of acquisition of HPV infection or in influencing events of the natural history of cervical neoplasia that occur following the establishment of a persistent HPV infection. Virtually all cervical carcinoma specimens contain HPV DNA, which suggests that HPV infection is a necessary cause of cervical neoplasia. This is the first instance in which a necessary cause has been demonstrated in cancer epidemiology--a realization that has obvious implications for primary and secondary prevention of this neoplastic disease.

Translational approaches to improving cervical screening

Screening programmes for cervical cancer using the current test--the Pap smear--have markedly reduced the incidence of the disease. However, an individual Pap test is of limited sensitivity and is difficult and expensive to perform. Increased understanding of the molecular pathogenesis of cervical cancer indicates that new approaches to screening might offer increased accuracy, affordability and the potential for automation. Such approaches exemplify how improved understanding of the biology of neoplasia might be translated into clinical benefit.