Bacterial vaginosis and cervical intraepithelial neoplasia-cause or coincidence?

Association between bacterial vaginosis and cervical intraepithelial neoplasia: systematic review and meta-analysis

OBJECTIVE

Bacterial vaginosis (BV), the most common vaginal disorder among women of reproductive age, has been suggested as co-factor in the development of cervical cancer. Previous studies examining the relationship between BV and cervical intra-epithelial neoplasia (CIN) provided inconsistent and conflicting results. The aim of this study is to clarify the association between these two conditions.

METHODS

A systematic review and meta-analysis were conducted to summarize published literature on the association between BV and cervical pre-cancerous lesions. An extensive search of electronic databases Medline (Pubmed) and Web of Science was performed. The key words 'bacterial vaginosis' and 'bacterial infections and vaginitis' were used in combination with 'cervical intraepithelial neoplasia', 'squamous intraepithelial lesions', 'cervical lesions', 'cervical dysplasia', and 'cervical screening'. Eligible studies required a clear description of diagnostic methods used for detecting both BV and cervical pre-cancerous lesions. Publications were included if they either reported odds ratios (OR) and corresponding 95% confidence intervals (CI) representing the magnitude of association between these two conditions, or presented data that allowed calculation of the OR.

RESULTS

Out of 329 articles, 17 cross-sectional and 2 incidence studies were selected. In addition, two studies conducted in The Netherlands, using the national KOPAC system, were retained. After testing for heterogeneity and publication bias, meta-analysis and meta-regression were performed, using a random effects model. Although heterogeneity among studies was high (χ(2) = 164.7, p<0.01, I(2) = 88.5), a positive association between BV and cervical pre-cancerous lesions was found, with an overall estimated odds ratio of 1.51 (95% CI, 1.24-1.83). Meta-regression analysis could not detect a significant difference between studies based on BV diagnosis, CIN diagnosis or study population.

CONCLUSIONS

Although most studies were cross-sectional and heterogeneity was high, this meta-analysis confirms a connection between BV and CIN.

Bacterial vaginosis as a risk factor for high-grade cervical lesions and cancer in HIV-seropositive women

OBJECTIVE

To assess the effect of bacterial vaginosis (BV) on the risk of high-grade squamous intraepithelial lesions (HSIL) among HIV-seropositive women.

METHODS

A hospital-based prospective cohort study of HIV-seropositive women was conducted in Johannesburg, South Africa from January 2005 to September 2009. Multivariate log-binomial and Poisson regressions were used to estimate prevalence and rate ratios, respectively.

RESULTS

Among 1954 HIV-seropositive women, the baseline prevalence of HSIL was 17%. BV prevalence was high (54%) and showed no association with prevalence of HSIL (adjusted prevalence ratio, 1.12; 95% confidence intervals (CI), 0.92-1.35) nor with cervical lesion progression at follow-up visit (n=503) (adjusted rate ratio: 1.00; 95% CI, 0.65-1.53).

CONCLUSION

Among HIV-seropositive women, BV was not associated with an increased risk of HSIL or cervical lesion progression.

Inflammatory events as detected in cervical smears and squamous intraepithelial lesions

The Dutch cytological coding system, KOPAC, enables to code for eight inflammatory events, that is koilocytosis (related to human papillomavirus (HPV)), Trichomonas, dysbacteriosis [related to bacterial vaginosis (BV)], Candida, Gardnerella, Actinomyces, Chlamydia, and non-specific inflammation (leucocytosis). This study presents an analysis of 1,008,879 smears. Of each smear, the age of the woman and the reason for smear taking (screening or indication) was available. The cytoscores (per mille) for these codes were calculated. For the screening smears, the cytoscores were for koilocytosis (HPV) 2.6, for Trichomonas vaginalis 1.9, for dysbacteriosis 31.4, for Candida albicans 9.8, for Gardnerella vaginalis 0.7, for Actinomyces 6.9, for Chlamydia 0.8, and for non-specific inflammatory changes 66.4. For the calculation of the Odds Ratio (OR), normal smears were used as a reference. The cytoscores for Chlamydia and Gardnerella covaried with high grade SIL (HSIL), with an OR of 7 and 12, respectively. In addition, the OR for Trichomonas vaginalis, for dysbacteriosis, and for leucocytosis proved to be significantly high in the indication smears. This study provides an oversight of HSIL and the full range of cervical infections as detected by cytology, proving that this infectious byproduct of screening can be very valuable.

Association between bacterial vaginosis and cervical intraepithelial neoplasia

OBJECTIVE

The aim of this study was to determine whether the presence of bacterial vaginosis (BV) is associated with cervical intraepithelial neoplasia (CIN) and human papilloma virus (HPV) infection.

METHODS

A total of 588 women who had abnormal Pap smears and had finally undergone loop electrosurgical excision procedure (LEEP) in our institute from September 2002 to May 2006 were selected. The screening tests for BV were done in 552 of the 588, and BV was diagnosed if three of the following four findings were satisfied: presence of abnormal discharge, vaginal pH>4.5, presence of clue cells, positive amine or whiff test. Five hundred and five patients had HPV typing tests by the HPV DNA chip. Forty two patients diagnosed with invasive cancer were excluded from this study. CIN was subdivided into low-grade CIN (CIN I) and high-grade CIN (CIN II/III) groups.

RESULTS

There was no statistically significant difference in patient characteristics between BV-present and BV-absent group. The incidence of CIN was significantly higher in the BV-present group (p=0.043), however, no statistical significance of BV on CIN was observed on multivariate analysis. HPV infection showed no significant relationship with BV. BV with or without HPV infection did not influence the incidence of CIN, regardless of the severity.

CONCLUSION

There was significant correlation between BV and the presence of CIN, regardless of the severity of CIN. In addition, there was no significant association between the presence of BV and HPV infection.

Candida and dysbacteriosis: a cytologic, population-based study of 100,605 asymptomatic women concerning cervical carcinogenesis

BACKGROUND

The objective of this study was to investigate whether the presence of vaginal Candida or dysbacteriosis predisposes women to an increased susceptibility for (pre)neoplasia over time.

METHODS

A retrospective, longitudinal, cohort study was performed and was conducted in a population of 100,605 women, each of whom had 2 smears taken over a period of 12 years as part of the Dutch Cervical Screening Program. From these women, a cohort of 1439 women with Candida and a cohort of 5302 women with dysbacteriosis were selected as 2 separate study groups. The control cohort consisted of women who had completely normal cervical smears (n = 87,903 women). These groups were followed retrospectively over time. The odds ratios (OR) for squamous abnormalities in the follow-up smear for the women in these 3 cohorts were established.

RESULTS

The dysbacteriotic cohort was significantly more likely to have low-grade squamous intraepithelial lesions (LSIL) and high-grade squamous intraepithelial lesions (HSIL+) in their follow-up smear (OR, 1.85; 95% confidence interval [95% CI], 1.28-2.67 and OR, 2.00; 95% CI, 1.31-3.05, respectively) compared with women in the control group. In contrast, the Candida cohort had no significantly increased or decreased risk of developing SIL. The equivocal diagnosis 'atypical squamous cells of undetermined significance' was rendered significantly more often in the follow-up smear of both study cohorts (Candida cohort: OR, 1.42; 95% CI, 1.03-1.95; dysbacteriotic cohort: OR, 1.44; 95% CI, 1.22-1.71).

CONCLUSIONS

The results from this study indicated that the presence of Candida vaginalis was not associated with an increased risk for SIL over time. In contrast, women with dysbacteriosis had a significantly increased risk of developing (pre)neoplastic changes. These findings should be taken into account in further research concerning predisposing factors for cervical carcinogenesis.

Is bacterial vaginosis associated with cervical intraepithelial neoplasia?

Previous research has produced conflicting results regarding the association of bacterial vaginosis (BV) and cervical intraepithelial neoplasia (CIN). These studies have been weakened in their conclusions mainly by failure to adequately control for the presence of sexually transmitted infections (STIs). One proposed mechanism suggesting that carcinogenic nitrosamines acting either independently or via human papilloma virus (HPV) has not been fully tested previously. We undertook a prospective, case-controlled, cross-sectional study where the presence of STIs, in particular human papillomavirus (HPV) which is known to be associated with the development of CIN, was controlled for. Women with BV were not found to have CIN more frequently than women with normal vaginal flora and the quantities of nitrosamines produced by women with BV did not differ significantly from women without BV. We thus found that BV is not associated with CIN.

Infection and cervical intraepithelial neoplasia

The impact of sexually transmitted diseases (STDs) on the development of cervical intraepithelial neoplasia (CIN) has been increasingly recognized over the last 20 years. Much attention has been focused on human papillomavirus (HPV) and the potential for screening for certain HPV types alongside standard cervical cytology in the hope of identifying those females at particular risk of developing high grade CIN or invasive carcinoma. Some infections, for example herpes simplex virus (HSV), have been heavily investigated in the past as they were thought to be involved in the development of CIN but were subsequently discounted. Also discounted as causes of CIN are Neisseria gonorrhoeae (NG) and Chlamydia trachomatis (CT). These infections were found to be associated with higher rates of CIN in early studies but transpired to be markers for the presence of other infections and pathology and therefore not themselves directly responsible for cytological changes. The role of bacterial vaginosis (BV) is the focus of several current investigations, not only in the genesis of CIN but also in the development of other gynecological and obstetric conditions and complications. Evidence to implicate Trichomonas vaginalis (TV) in the genesis of CIN is conflicting, but there is some evidence that it may exert its influence in a similar way to that hypothesized for BV, ie via abnormal amines. It is well known that there is a high level of concordance of STDs whereby the presence of one infection greatly increases the likelihood of there being one or more others present. There may be a synergism between some infections with regard to the causation of CIN, although the evidence for this is putative. Presented here is an overview of current and previous research in the field of lower genital tract infection as it relates to the development of CIN.