Human papillomavirus (HPV) screening and cervical cancer burden. A Brazilian perspective

This review tackles the issues related to disease burden caused by cervical cancer (CC) and its precursor (CIN) lesions in Brazil. A special focus is given to new technologies with potential to interfere with the development of CC by reducing the high-risk human papillomavirus (hr-HPV)-induced lesions that remain a major public health burden in all developing countries where organized screening programs do not exist. Globally, 85 % of all incident CC and 50 % of CC deaths occur in the developing countries. Unfortunately, most regions of Brazil still demonstrate high mortality rates, ranking CC as the second most common cancer among Brazilian women. Recently, CC screening programs have been tailored in the country to enable early detection of CC precursor lesions and thereby reduce cancer mortality. A combination of HPV testing with liquid-based cytology (LBC) seems to be a promising new approach in CC screening, with high expectation to offer an adequate control of CC burden in this country

Single-tube multiplex PCR using type-specific E6/E7 primers and capillary electrophoresis genotypes 21 human papillomaviruses in neoplasia

<p>Abstract</p> <p>Background</p> <p>Human papillomavirus (HPV) <it>E6/E7 </it>type-specific oncogenes are required for cervical carcinogenesis. Current PCR protocols for genotyping high-risk HPV in cervical screening are not standardized and usually use consensus primers targeting HPV capsid genes, which are often deleted in neoplasia. PCR fragments are detected using specialized equipment and extra steps, including probe hybridization or primer extension. In published papers, analytical sensitivity is typically compared with a different protocol on the same sample set.</p> <p>A single-tube multiplex PCR containing type-specific primers was developed to target the <it>E6/E7 </it>genes of two low-risk and 19 high-risk genotypes (HPV6, 11 and 16, 18, 26, 31, 33, 35, 39, 45, 51, 52, 53, 56, 58, 59, 66, 68, 70, 73 and 82) and the resulting short fragments were directly genotyped by high-resolution fluorescence capillary electrophoresis.</p> <p>Results</p> <p>The method was validated using long oligonucleotide templates, plasmid clones and 207 clinical samples of DNA from liquid-based cytology, fresh and formalin-fixed specimens and FTA Microcards^®imprinted with cut tumor surfaces, swabbed cervical cancers or ejected aspirates from nodal metastases of head and neck carcinomas. Between one and five long oligonucleotide targets per sample were detected without false calls. Each of the 21 genotypes was detected in the clinical sample set with up to five types simultaneously detected in individual specimens. All 101 significant cervical neoplasias (CIN 2 and above), except one adenocarcinoma, contained <it>E6/E7 </it>genes. The resulting genotype distribution accorded with the national pattern with HPV16 and 18 accounting for 69% of tumors. Rare HPV types 70 and 73 were present as the sole genotype in one carcinoma each. One cervical SCC contained DNA from HPV6 and 11 only. Six of twelve oropharyngeal cancer metastases and three neck metastases of unknown origin bore <it>E6/E7 </it>DNA; all but one were HPV16. One neck aspirate contained atypical squames with HPV26.</p> <p>Analytical sensitivity in dilute plasmid mixes was variable.</p> <p>Conclusions</p> <p>A primer-rich PCR readily detects the <it>E6/E7 </it>oncogenes of 21 HPV types in cellular and fixed tissue specimens. The method is straightforward, robust and reproducible and avoids post-PCR enzymatic and hybridization steps while detecting HPV with high clinical sensitivity in significant HPV-related neoplasia regardless of specimen type.</p

Different cervical cancer screening approaches in a Chinese multicentre study

To evaluate alternative cervical cancer screening methods, digital colposcopy and collection of cervical exfoliated cells for liquid-based cytology (LBC) and hybrid capture 2 (HC2) testing were performed among 2562 women aged 15–59 years in three study sites in the People's Republic of China (rural Shanxi province, Shenyang city in Liaoning province and Shenzhen city in Guangdong province). Visual inspection with acetic acid (VIA) was also evaluated independently from colposcopy. A total of 74 cases of histologically confirmed cervical intraepithelial neoplasia grade 2 or worse (CIN2+) were identified, and 16 CIN2+ cases were imputed among unbiopsied women to correct for verification bias. Corrected sensitivity for CIN2+ was 37% for VIA, 54% for colposcopy, 87% for LBC with a threshold of atypical cells of undetermined significance (LBC⩾ASCUS), 90% for HC2, 84% for LBC using HC2 to triage ASCUS and 96% for positivity to LBC⩾ASCUS or HC2. For VIA, sensitivity was much lower among women ⩾40 years (12%) than those aged ⩽39 years (50%). Specificity varied from 77% for positivity to LBC⩾ASCUS or HC2, up to 94% for LBC using HC2 to triage ASCUS. In conclusion, LBC, HC2 and their combinations performed well, whereas VIA missed a majority of CIN2+, particularly in older women. Digital colposcopy performed better than VIA, but still missed nearly half of CIN2+ in this study

A cost-utility analysis of cervical cancer vaccination in preadolescent Canadian females

<p>Abstract</p> <p>Background</p> <p>Despite the fact that approximately 70% of Canadian women undergo cervical cancer screening at least once every 3 years, approximately 1,300 women were diagnosed with cervical cancer and approximately 380 died from it in 2008. This study estimates the effectiveness and cost-effectiveness of vaccinating 12-year old Canadian females with an AS04-adjuvanted cervical cancer vaccine. The indirect effect of vaccination, via herd immunity, is also estimated.</p> <p>Methods</p> <p>A 12-health-state 1-year-cycle Markov model was developed to estimate lifetime HPV related events for a cohort of 12-year old females. Annual transition probabilities between health-states were derived from published literature and Canadian population statistics. The model was calibrated using Canadian cancer statistics. From a healthcare perspective, the cost-effectiveness of introducing a vaccine with efficacy against HPV-16/18 and evidence of cross-protection against other oncogenic HPV types was evaluated in a population undergoing current screening practices. The base-case analysis included 70% screening coverage, 75% vaccination coverage, $135/dose for vaccine, and 3$18,672-$31,687 per QALY-gained, the lower range representing inclusion of cross-protective efficacy and herd immunity. The cost per QALY-gained was most sensitive to duration of vaccine protection, discount rate, and the correlation between probability of screening and probability of vaccination.</p> <p>Conclusion</p> <p>In the context of current screening patterns, vaccination of 12-year old Canadian females with an ASO4-ajuvanted cervical cancer vaccine is estimated to significantly reduce cervical cancer and mortality, and is a cost-effective option. However, the economic attractiveness of vaccination is impacted by the vaccine's duration of protection and the discount rate used in the analysis.</p

Comparison of Hybrid capture 2 testing at different thresholds with cytology as primary cervical screening test

BACKGROUND: We evaluated the performance of primary high-risk human papillomavirus (hrHPV) testing by hybrid capture 2 (HC2) with different thresholds for positivity, in comparison with conventional cytology.METHODS: We used data of 25,871 women (aged 30-60 years) from the intervention group of the VUSA-Screen study (VU University Medical Center and Saltro laboratory population-based cervical screening study), who were screened by cytology and hrHPV. Primary outcome measure was the number of cervical intraepithelial neoplasia grade 3 or higher (CIN3+), detected within 3 years. We compared baseline cytology testing with three possible hrHPV screening strategies at different relative light unit/cutoff (RLU/CO) thresholds.RESULTS: Compared with baseline cytology testing, hrHPV DNA testing as a sole primary screening instrument did not yield a superior sensitivity, as well as lower colposcopy referral rate and lower false positivity rate at any RLU/CO threshold. The hrHPV screening at 1 RLU/CO threshold with cytology triage at baseline and at 12 months revealed the highest sensitivity for CIN3+ (relative sensitivity of 1.32), although still displaying a lower colposcopy referral rate than cytology testing (relative colposcopy rate of 0.94). Higher thresholds (&gt;1 RLU/CO) yielded lower colposcopy rates, but resulted in substantial loss in sensitivity.CONCLUSIONS: The hrHPV testing at the commonly used threshold of 1 RLU/CO with cytology triage at baseline and at 12 months showed a much higher sensitivity with a lower colposcopy referral rate compared with cytology testing.</p

Canadian oncogenic human papillomavirus cervical infection prevalence: Systematic review and meta-analysis

<p>Abstract</p> <p>Background</p> <p>Oncogenic human papillomavirus (HPV) infection prevalence is required to determine optimal vaccination strategies. We systematically reviewed the prevalence of oncogenic cervical HPV infection among Canadian females prior to immunization.</p> <p>Methods</p> <p>We included studies reporting DNA-confirmed oncogenic HPV prevalence estimates among Canadian females identified through searching electronic databases (e.g., MEDLINE) and public health websites. Two independent reviewers screened literature results, abstracted data and appraised study quality. Prevalence estimates were meta-analyzed among routine screening populations, HPV-positive, and by cytology/histology results.</p> <p>Results</p> <p>Thirty studies plus 21 companion reports were included after screening 837 citations and 120 full-text articles. Many of the studies did not address non-response bias (74%) or use a representative sampling strategy (53%).</p> <p>Age-specific prevalence was highest among females aged < 20 years and slowly declined with increasing age. Across all populations, the highest prevalence estimates from the meta-analyses were observed for HPV types 16 (routine screening populations, 8 studies: 8.6% [95% confidence interval 6.5-10.7%]; HPV-infected, 9 studies: 43.5% [28.7-58.2%]; confirmed cervical cancer, 3 studies: 48.8% [34.0-63.6%]) and 18 (routine screening populations, 8 studies: 3.3% [1.5-5.1%]; HPV-infected, 9 studies: 13.6% [6.1-21.1%], confirmed cervical cancer, 4 studies: 17.1% [6.4-27.9%].</p> <p>Conclusion</p> <p>Our results support vaccinating females < 20 years of age, along with targeted vaccination of some groups (e.g., under-screened populations). The highest prevalence occurred among HPV types 16 and 18, contributing a combined cervical cancer prevalence of 65.9%. Further cancer protection is expected from cross-protection of non-vaccine HPV types. Poor study quality and heterogeneity suggests that high-quality studies are needed.</p