Eliane Duarte-Franco

Human Papillomavirus Infections with Multiple Types and Risk of Cervical Neoplasia

Background: Besides an established role for certain human papillomavirus (HPV) genotypes in the etiology of cervical cancer, little is known about the influence of multiple-type HPV infections on cervical lesion risk. We studied the association between multiple HPV types and cervical lesions among 2,462 Brazilian women participating in the Ludwig-McGill study group investigation of the natural history of HPVs and cervical neoplasia. Methods: Cervical specimens were typed by a PCR protocol. The cohorts repeated-measurement design permitted the assessment of the relation between the cumulative and concurrent number of HPV types and any-grade squamous intraepithelial lesions (SIL) and high-grade SIL (HSIL). Result: At individual visits, 1.9% to 3.2% of the women were infected with multiple HPVs. Cumulatively during the first year and the first 4 years of follow-up, 12.3% and 22.3% were infected with multiple types, respectively. HSIL risk markedly increased with the number of types [odds ratio (OR), 41.5; 95% confidence interval (95% CI), 5.3-323.2 for single-type infections; OR, 91.7; 95% CI, 11.6-728.1 for two to three types; and OR, 424.0; 95% CI, 31.8-5651.8 for four to six types, relative to women consistently HPV-negative during the first year of follow-up]. The excess risks for multiple-type infections remained after exclusion of women infected with HPV-16, with high-risk HPV types, or persistent infections, particularly for any-grade SIL. Coinfections involving HPV-16 and HPV-58 seemed particularly prone to increase risk. Conclusion: Infections with multiple HPV types seem to act synergistically in cervical carcinogenesis. These findings have implications for the management of cervical lesions and prediction of the outcome of HPV infections. (Cancer Epidemiol Biomarkers Prev 2006;15(7):1274–80)

Viral load as a predictor of the risk of cervical intraepithelial neoplasia

HPV infections are believed to be a necessary cause of cervical cancer. Viral burden, as a surrogate indicator for persistence, may help predict risk of subsequent SIL. We used results of HPV test and cytology data repeated every 4–6 months in 2,081 women participating in a longitudinal study of the natural history of HPV infection and cervical neoplasia in São Paulo, Brazil. Using the MY09/11 PCR protocol, 473 women were positive for HPV DNA during the first 2 visits. We retested all positive specimens by a quantitative, low‐stringency PCR method to measure viral burden in cervical cells. Mean viral loads and 95% CIs were calculated using log‐transformed data. RRs and 95% CIs of incident SIL were calculated by proportional hazards models, adjusting for age and HPV oncogenicity. The risk of incident lesions increased with viral load at enrollment. The mean number of viral copies/cell at enrollment was 2.6 for women with no incident lesions and increased (trend p = 0.003) to 15.1 for women developing 3 or more SIL events over 6 years of follow‐up. Compared to those with <1 copy per cell in specimens tested during the first 2 visits, RRs for incident SIL increased from 1.9 (95% CI 0.8–4.2) for those with 1–10 copies/cell to 4.5 (95% CI 1.9–10.7) for those with >1,000 copies/cell. The equivalent RR of HSIL for >1,000 copies/cell was 2.6 (95% CI 0.5–13.2). Viral burden appears to have an independent effect on SIL incidence. Measurement of viral load, as a surrogate for HPV persistence, may identify women at risk of developing cervical cancer precursors.

High grade cervical lesions are caused preferentially by non-European variants of HPVs 16 and 18

The intratypic variability of HPVs 16 and 18 has been extensively studied and has been used as an important tool in epidemiological studies of viral transmission, persistence and progression to clinically relevant cervical lesions. Infections by non‐European variants of HPVs 16 and 18 are associated with an increased risk for the development of high grade squamous intraepithelial lesions (HSIL). Our aim was to correlate the intratypic molecular variability of both HPV types and risk of persistent infection and lesion outcome in a cohort study conducted in Brazil. We characterized molecular variants of HPV types 16 and 18 by sequencing a fragment of the LCR, and of the E6 and L1 genes, for HPV‐16 variants only. For both types, European variants composed the most prevalent and diverse group. Persistent infections with HPV‐18 were associated with continuous detection of European variants. However, risk for simultaneous detection of HSIL and HPV DNA was higher in women harboring non‐European variants of HPV‐16. The same trend was observed with HSIL detected during follow‐up. Our study confirms the association between non‐European variants and risk of cervical neoplasia, and highlights the importance of their geographic distribution for cervical cancer risk assessment.

Randomized controlled trial of human papillomavirus testing versus Pap cytology in the primary screening for cervical cancer precursors: Design, methods and preliminary accrual results of the Canadian cervical cancer screening trial (CCCaST)

Since infection with oncogenic human papillomavirus (HPV) has been considered a necessary cause of cervical cancer, tests for oncogenic HPV types have been proposed as adjuncts or replacements to Pap cytology. We designed the Canadian Cervical Cancer Screening Trial (CCCaST) to compare the relative efficacy of HPV DNA testing and Pap cytology in primary screening for cervical cancer and its high‐grade precursors. CCCaST randomized women aged 30–69 years in Montreal (Quebec) and in St. Johns (Newfoundland) to 1 of 2 screening groups: focus on Pap (conventional) or focus on HPV testing (Hybrid Capture 2). Women in both arms received both tests, but were randomized as to their order, the first test being the index test. Women with an abnormal Pap test or a positive HPV test underwent colposcopy and biopsy, as did a random sample of women with a negative index test. CCCaST enrolled 9,667 women between October 2002 and October 2004. At enrolment, 2.8% had an abnormal Pap test, 6.1% had a positive HPV test and 1.1% were abnormal in both tests. ASC‐US was the most frequent cytological abnormality, representing 64% of abnormal Pap results. The frequency of abnormal Pap and HPV results decreased with increasing age and the proportion of HPV‐positive results increased with the severity of Pap abnormality. Efficacy analysis will determine if the extra referrals with HPV DNA testing will translate into a relevant increase in high‐grade cervical cancer precursor detection. Because of its design, CCCaST will provide sound evidence for formulating cervical cancer screening strategies.

Dietary Intake and Risk of Persistent Human Papillomavirus (HPV) Infection: The Ludwig-McGill HPV Natural History Study

The association between dietary intake and persistence of type-specific human papillomavirus (HPV) infection, during a 12-month period, among 433 women participating in the Ludwig-McGill HPV Natural History Study was evaluated by use of a nested case-control design. Dietary intake was assessed by a food-frequency questionnaire at the month-4 visit. HPV status was assessed at months 0, 4, 8, and 12 by polymerase chain reaction (MY09/11). Only women who ever tested positive for HPV were included in the present study: 248 had transient HPV infections (1 of 4 positive tests or nonconsecutively positive), and 185 had persistent HPV infections (> or =2 consecutive tests positive for the same HPV type). Risk of type-specific, persistent HPV infection was lower among women reporting intake values of beta-cryptoxanthin and lutein/zeaxanthin in the upper 2 quartiles and intake values of vitamin C in the upper quartile, compared with those reporting intake in the lowest quartile. Consumption of papaya > or =1 time/week was inversely associated with persistent HPV infection.

Cancer of the Uterine Cervix

Health issueCervical cancer is one of the most common malignant diseases of women; it is diagnosed in almost half a million women every year and half as many die from it annually. In Canada and other industrialized countries, its incidence has decreased due to cytology screening. However, invasive cases still occur, particularly among immigrant groups and native Canadian women. Although incidence of squamous cell carcinomas has decreased, the proportion of adenocarcinomas has increased because Pap cytology is ineffective to detect these lesions.Key findingsIn Canada, cervical cancer will cause an estimated 11,000 person-years of life lost. In most Canadian provinces, early detection is dependent on opportunistic screening. Primary prevention can be achieved through health education (sexual behavior modification) and vaccination to prevent infection from Human Papillomavirus (HPV). The initial results from vaccination trials are encouraging but wide scale use is more than a decade away.Data gaps and recommendationsMost cases of cervical cancer occur because the Pap smear was either false negative, was not done or not done often enough. Appropriate recommendations and guidelines exist on implementation of cytology-based programs. However, most Canadian women do not have access to organized screening. Further research is needed to 1) evaluate automated cytology systems; 2) define appropriate management of precursor lesions and 3) deliver definitive evidence of HPV testing efficacy in long-term follow-up studies with invasive cancer as an outcome and 4) provide Canadian data to justify augmenting or modifying current programs to use HPV testing in secondary triage of equivocal Pap smears.

Selected class I and class II HLA alleles and haplotypes and risk of high-grade cervical intraepithelial neoplasia

Human leukocyte antigens (HLAs) present foreign antigens to the immune system and may be important determinants of cervical neoplasia. Previously published associations between HLA and cervical neoplasia exhibit considerable variation in findings. The biomarkers of cervical cancer risk (BCCR) case‐control study addressed the role of specific HLA alleles as cofactors in the development of high‐grade cervical intraepithelial neoplasia (HG‐CIN) based on the most consistent evidence from published literature. Cases (N = 381) were women with histologically‐confirmed HG‐CIN attending colposcopy clinics and controls (N = 884) were women from outpatient clinics with normal cytological screening smears. Subjects were mainly of French‐Canadian descent. Cervical specimens were tested for human papillomavirus (HPV) DNA and HLA genotypes by PGMY L1 consensus primer PCR and a PCR sequence‐specific primer method, respectively. Unlike other studies, the DQB1*03 and DRB1*13 allele groups were not associated with risk of HG‐CIN. The B7‐DRB1*1501‐DQB1*0602 haplotype was associated with a 41% overall reduction in HG‐CIN risk (odds ratio [OR] = 0.59; 95% confidence interval [CI]: 0.36–0.96), and an 83% reduction in risk of HG‐CIN among HPV 16 or HPV 18‐positive subjects (OR = 0.17; 95%CI: 0.05–0.54). Paradoxically, however, the same haplotype was associated with HPV 16/18 infection risk among controls (OR = 8.44, 95%CI: 1.12–63.73). In conclusion, the B7‐DRB1*1501‐DQB1*0602 haplotype was protective against HG‐CIN, especially in individuals infected with oncogenic HPV, but the mechanism of the association seems to involve multiple steps in the natural history of HPV and CIN.

Evidence-based policy recommendations on cancer screening and prevention

Ideally, practice guidelines for cancer prevention should reflect the available empirical evidence. Although the most persuasive arguments for the efficacy of an intervention come from randomized controlled trials (RCTs), such studies are not always feasible because of ethical or logistical reasons. The advent of evidence-based medicine has underscored the need for consortia of researchers specialized in reviewing the biomedical literature on a systematic basis, ranking studies according to their design, quality, and generalizability of results. This review summarizes the recommendations and policies on screening and prevention of specific types of cancers from North American and international organizations such as: the National Cancer Institutes Physicianss Data Query Program, the US Preventive Services Task Force, the Canadian Task Force on the Preventive Health Care Force, and the Cochrane Collaboration.

Prospects for controlling cervical cancer at the turn of the century

Cervical cancer morbidity and mortality have decreased substantially during the last 50 years mostly due to successful organized or opportunistic screening with Pap cytology in high and middle income countries. In many low income countries Pap cytology screening is yet to be effectively implemented or has failed to reduce cervical cancer rates to an appreciable extent. The fact that infection with certain human papillomavirus (HPV) types is now recognized as a necessary cause of this disease has led to new research fronts on prevention of cervical cancer. Testing for HPV DNA has shown great promise as a screening tool with better sensitivity but somewhat lower specificity than Pap cytology. In combination with the latter, HPV testing has the potential to improve the negative predictive value of cytology, thus allowing for increased testing intervals, which would lower program costs with acceptable safety. Advances in cytology processing and automation have also led to new screening approaches that are increasingly gaining acceptance in high and middle income countries. For low income countries, visual inspection with acetic acid has proven to be an effective alternative to conventional Pap cytology, especially in settings where no screening programs have been implemented. Concerning primary prevention of cervical cancer, recent research on the safety and efficacy of candidate prophylactic vaccines against HPV have shown very promising results with nearly 100% efficacy in preventing persistent infections and development of cervical cancer precursors. However, policy makers are strongly cautioned to avoid deferring decisions concerning the implementation of cervical cancer screening under the expectation that a successful vaccine could obviate the need for secondary prevention strategies. This paper is available too at: http://www.insp.mx/salud/index.html.

Insulin-like Growth Factor-I and Risk of High-Grade Cervical Intraepithelial Neoplasia

Insulin-like growth factors (IGF) and their binding proteins (IGFBP) have been implicated in the risk of several epithelial or glandular tumors, including prostate cancer, breast cancer, and colon cancer. Cervical cancer, which is also of epithelial origin, has been shown to overexpress receptors for IGF-I, and plasma levels of IGF-I have been positively associated with cervical cancer precursors in one epidemiologic study. In this case-control study, we investigated plasma levels of IGF-I and IGFBP-3 in relation to the risk of histologically confirmed high-grade cervical intraepithelial neoplasia (HGCIN) and the risk of human papillomavirus (HPV) infection. Included in this analysis were 329 cases and 621 controls recruited from clinics affiliated with two Montréal-area hospital centers. We observed a reduced risk of HGCIN for increasing levels of IGF-I, with an adjusted odds ratio (OR) of 0.40 (95% confidence interval, 0.19-0.87) for the highest quartile relative to the lowest quartile of IGF-I. No association was observed between IGFBP-3 levels and HGCIN. Among controls, IGF-I was associated with a decreased risk of being positive for HPV-16 or HPV-18, with an adjusted odds ratio of 0.20 (95% confidence interval, 0.05-0.87) for the highest quartile relative to the lowest quartile of IGF-I. There was no association observed between IGFBP-3 levels and HPV infection status. IGF-I–mediated effects seemed to predominate among women <30 years of age. In contrast to the previously reported study, our results suggest that levels of IGF-I in young women may be inversely associated with HGCIN, a precursor to cervical cancer. (Cancer Epidemiol Biomarkers Prev 2007;16(4):716–22)