Are we ready for a paradigm change in cervical cancer screening?

The lysine acetyltransferase GCN5 contributes to human papillomavirus oncoprotein E7-induced cell proliferation via up-regulating E2F1

General control nondepressible 5 (GCN5), the first identified transcription-related lysine acetyltransferase (KAT), is an important catalytic component of a transcriptional regulatory SAGA (Spt-Ada-GCN5-Acetyltransferase) and ATAC (ADA2A-containing) complex. While GCN5 has been implicated in cancer development, its role in cervical cancer is not known. The human papillomavirus (HPV) oncoprotein E7 abrogates the G1 cell cycle checkpoint and induces genomic instability, which plays a central role in cervical carcinogenesis. In this study, we observed that GCN5 was up-regulated in HPV E7-expressing cells, knockdown of GCN5 inhibited cell cycle progression and DNA synthesis in HPV E7-expressing cells. Notably, GCN5 knockdown reduced the steady-state levels of transcription factor E2F1. Depletion of E2F1 caused G1 arrest while overexpression of E2F1 rescued the inhibitory effects of GCN5 knockdown on G1/S progression in HPV E7-expressing cells. Results from chromatin immunoprecipitation (ChIP) assays demonstrated that GCN5 bound to the E2F1 promoter and increased the extent of histone acetylation within these regions. GCN5 also acetylated c-Myc and increased its ability to bind to the E2F1 promoter. Knockdown of c-Myc reduced the steady-state levels of E2F1 and caused G1 arrest. These results revealed a novel mechanism of E7 function whereby elevated GCN5 acetylates histones and c-Myc to regulate E2F1 expression and cell cycle progression.

Women's preferences for cervical cancer screening: a study using a discrete choice experiment

OBJECTIVES

Recent policy recommendations for cervical screening include liquid-based cytology. This new approach could improve laboratory throughput, reducing the waiting time for test results. New guidelines also standardize the interval for screening, with women aged 25-50 offered screening every 3 years and women aged 50-64 every 5 years. Quantitative evidence on the preferences of women for alternative screening programs is limited; this study, therefore, elicits such preferences.

METHODS

A postal questionnaire using a discrete choice experiment was mailed to 2,000 women in the Tayside Health Board region of Scotland.

RESULTS

A response rate of 44 percent from those women who had previously had a smear was achieved. Women had a significant positive preference for reductions in recall rates and waiting time for results. Women preferred more frequent screening, particularly those aged 50+. Expected reductions in the chance of recall from the conventional Pap smear to the new liquid-based cytology were associated with a willingness to pay of pound 41. Women aged 50+ would be willing to pay pound 42 to increase the frequency of screening from every 5 to every 3 years. Service characteristics did not influence screening participation.

CONCLUSIONS

Guidance to move to liquid-based cytology will meet women's preferences for fewer repeat cervical smears and should reduce waiting time for results. However, proposals to increase screening intervals for those aged 50+ are inconsistent with the preferences for this age group. From a policy perspective, our study results suggest that the changes in attributes of the service such as unsatisfactory smear rates and frequency of screening, will improve service efficiency without affecting participation rates.

Screening for gynaecological cancers

BACKGROUND

The role of screening in gynaecological cancers is under evaluation. With mass screening proven effective in significantly reducing cervical cancer mortality, there is an interest in developing other screening methods to detect gynaecological malignancies early. This review covers advances in cervical cancer screening, strategies being investigated in ovarian cancer screening and the lack of justification in screening for endometrial, vulval and vaginal cancers.

METHODS

A Medline based literature search was performed for articles relating to screening for different gynaecological malignancies. Additional original papers cited in those identified by the initial search were also reviewed.

RESULTS

Advances in cervical cancer screening include liquid-based cytology and HPV testing. Results of ongoing trials are awaited before these can be fully implemented. The results of the two large, multicentre, randomised controlled trials being conducted in the United Kingdom and United States (UKCTOCS and PLCO study, respectively) to assess impact of screening on ovarian cancer mortality will shed some light on the need to implement screening for ovarian cancer in the general population. Novel markers, serum proteomic profiles and Doppler are some of the other technologies being explored. Currently, screening for endometrial cancer is not advocated as most women present with symptoms in early disease with good survival outcomes. Vulval and vaginal cancers are too rare to justify mass screening.

CONCLUSION

Methods to screen for various gynaecological malignancies need further evaluation before implementation in the general population. Results of large multicentred trials are awaited. Presently, screening for endometrial, vaginal and vulval cancers is not justified.

[Contribution of viral typing in cytological anomalies of the cervix]

Management practices for low-grade cervical lesions identified on screening swabs have been modified by research on the HPV. The appropriate approach for low-grade lesions is particularly difficult to determine due to the potential risk of malignant transformation coupled with the cost implications of treating lesions which will heal spontaneously in the majority of patients. The diagnosis of these low-grade lesions can be improved by thin layer swabs which have a greater sensitivity than conventional swabs. The current consensus is that swab results should be expressed according to the Bethesda classification. Routine tests for HPV (Hybrid Capture II) should be reserved for patients with an ASC-US swab. Colposcopy is indicated if the swab is positive for a low-grade lesion followed by cytology if the colposcopy is normal. If there is no evidence of HPV, search for oncogenes can lighten the treatment regimen due to the high specificity of the test. If a low-grade histological lesion (CIN1) is proven, cytocolposcopic surveillance should be proposed, surgical resection being undertaken in colposcopy cannot be performed. Here again search for HPV oncogenes at one year is an interesting alternative if the examination is negative. These practices are applicable in adolescents and HIV- positive patients who are particularly exposed to HPV.

Human papillomavirus testing for primary screening in women at low risk of developing cervical cancer. The Greek experience

OBJECTIVE

To compare the performance of human papillomavirus (HPV) DNA detection against routine Papanicolaou smear for the detection of low- and high-grade cervical intraepithelial neoplasia in a low-risk population.

MATERIALS AND METHODS

A cross-sectional study was performed involving 1296 women attending six outpatient clinics in Northern Greece (Thessaloniki, Thermi, Mihaniona, Corfu, Veria, and Serres). Women underwent a gynecological examination, including collection of exfoliated cervical cells for Papanicolaou cytology and HPV DNA detection. Cytology was processed according the conventional routine manner, and HPV DNA was determined using the polymerase chain reaction technique. In positive cases of either method, a complete colposcopic evaluation was performed with directed biopsies. Tests (HPV DNA, cytology, and colposcopy) performance characteristics were determined using the histopathologic diagnosis as the reference standard.

RESULTS

HPV DNA testing showed a significantly better sensitivity than the Papanicolaou smear in detecting cervical intraepithelial neoplasia (75% versus 50% for high-grade lesions and 81.2% versus 50% for lesions of any grade, respectively). Specificity, and positive and negative predictive values did not significantly differ. Even after dividing women in younger or older than 30 years, the sensitivity of the HPV DNA test was greater than cytology (100% and 70% versus 50% for cytology in both groups, respectively), with a 6.3% loss in specificity when performed in women younger than 30 years.

CONCLUSION

HPV testing could be useful in screening women at low risk for cervical cancer, either as an adjunct tool to augment existing cytology programs or as a unique test of its own.

The future of research that promotes cancer screening

The authors draw on the lessons highlighted in preceding articles in the current supplement to provide recommendations for cancer screening intervention research and to highlight some of the many questions that will require further investigation.