The impact of herbal treatments on cervicovaginal human papillomavirus infection: a systematic review and meta-analysis

SUMMARY OBJECTIVE: This systematic review and meta-analysis aimed to investigate the effects of herbal treatments on cervicovaginal human papillomavirus infection. METHODS: A comprehensive literature search was conducted in PubMed, Scopus, Science Direct, and the Cochrane Library until December 2023, following Cochrane guidelines. Data were analyzed using the Review Manager computer program (Version 5.4.1). RESULTS: Five randomized controlled trials involving a total sample size of 662 women were included in the study. The pooled odds ratio for individuals testing negative for human papillomavirus after herbal intervention among human papillomavirus-positive patients was 1.86 (95% confidence interval (CI) 0.64–5.43), according to the fixed-effects model. Three out of the five studies indicated a significant relationship. The relationship between positive human papillomavirus infection and herbal treatments, measured by the fixed-effects model, resulted in a pooled odds ratio of 0.41 (95%CI 0.17–1.01), reporting a significant association (p=0.05). Subgroup analysis revealed a significant reduction in the relationship between herbal treatment and atypical squamous cells of undetermined significance (OR 0.16, 95%CI 0.03–0.88, p=0.04) but no significant impact on the relationship between herbal treatment and low-grade squamous intraepithelial lesion (OR 0.33, 95%CI 0.01–8.77, p=0.51). CONCLUSION: The meta-analysis suggests that herbal treatments reduce human papillomavirus infections. While herbal treatments show a significant reduction in atypical squamous cells of undetermined significance, they do not significantly impact the regression of low-grade squamous intraepithelial lesions.


Herbal treatments on cervicovaginal human papillomavirus infection
HPV infection.The study aimed to address the following questions: 1. What is the effect of herbal treatments on the treatment of HPV infection?2. What is the impact of herbal treatments on cytological regression?

Protocol registration
The PRISMA (preferred reporting items for systematic reviews and meta-analysis statement) guidelines was followed in preparing this systematic review and meta-analysis.Throughout the study, there were no instances requiring deviation from the protocol, and the study was concluded following the protocol registered in the PROSPERO database (CRD42023491610).

Eligibility criteria
The selection of studies adhered to the following criteria (PICOS) Exclusion criteria encompassed individuals under 18 years old, pregnant and breastfeeding women, those with known or suspected cervical cancer, HIV-positive patients, individuals with known allergies to herbal methods, animal studies, studies with unavailable full texts, and all studies not related to herbal treatments and incorporated theoretical studies, editorial comments, non-experimental studies such as only protocol studies and review papers, and articles using measurement tools with questionable validity.The inclusion of studies was limited to those with results or outcome tables available in English or Turkish.

Search strategy
For this systematic review, the literature search was conducted until December 20, 2023, using databases such as PubMed, Scopus, Science Direct, and the Cochrane Library.
The keywords included "HPV infection" OR "human papillomavirus" OR "cervicovaginal lesions" AND "curcumin" OR "polyphenon E" OR "myrtle" OR "epigallocatechin gallate" OR "herbal treatment."Additionally, systematic reference lists of articles and previous systematic reviews were searched.

Selection of studies and data extraction
Data were extracted by one reviewer (DC) using a data extraction form and checked by a second reviewer (AYK).Discrepancies between the two were resolved by a third researcher (NG).General characteristics of the studies (e.g., author, country, publication year, and study design), average age of participants, sample size of groups, type of intervention, duration of follow-up, intervention method, and primary outcome variables were included for each study (Table 1).

Quality assessment
Bias risk was assessed for seven domains: random sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, incomplete outcome data, selective reporting, and other biases.Other bias sources of this study included fundamental group imbalances and potential confounding factors.The risk of bias for each study was assessed as low, high, or unclear.The bias assessment was independently conducted by two researchers (AYK and DC), and in case of disagreement, the researchers reviewed the full text together to reach a consensus.

Data analysis
The relationships between herbal treatments and HPV parameters were estimated using pooled odds ratios (OR) and 95% confidence intervals (CI) with the Mantel-Haenszel method.Heterogeneity between studies was assessed using Cochran's Q test and Higgins' I², where I² greater than 50% indicated significant heterogeneity.Random-effects results were considered when I² was greater than 50%, and fixed-effects results were considered when I² was less than or equal to 50%.Various sensitivity analyses were conducted to assess the robustness of our results, excluding some articles considered of low quality.All analyses were performed using Review Manager 5.4.1 (The Nordic Cochrane Center, Copenhagen, Denmark).All tests were two-tailed, and a p-value less than 0.05 was considered statistically significant.21 full-text articles were assessed for eligibility, and five articles that met the criteria for RCTs were included in the analysis (Figure 1).

Study characteristics
This systematic review and meta-analysis encompass five studies involving a total of 662 women, aiming to examine the impact of herbal treatments on cervicovaginal HPV infection.
The studies were conducted in India 10 , the United States 11 , Iran 7 , Congo 12 , and Italy 13 .The study design for all included studies was RCTs.Table 1 provides a summary of the characteristics of the studies.In all studies within the scope of this review, herbal treatments were applied to women in the intervention group.The efficacy of herbal treatments on cervicovaginal HPV infection was assessed in all studies.In the control group, Aragona et al. 1 did not administer any intervention, while the other four studies 7,10-12 implemented a placebo intervention.

Quality of bias assessment
Except for one study 13 , all studies established a sufficient method for randomly assigning participants to cognitive-behavioral intervention groups.Therefore, we assessed the risk of bias as low in this domain for these studies.Except for Aragona et al., 1 all studies reported sufficient allocation concealment for randomization and were evaluated as having a low risk of bias, except for one study 11 where dropouts were balanced between intervention and control groups or were considered to have a low risk of bias due to the small number of dropouts that would not significantly impact the study.

Herbal treatments on cervicovaginal human papillomavirus infection
In three studies included in the meta-analysis [10][11][12] , we considered a high risk of bias because they discussed significant results, including adverse outcomes, and matched the reports in their records.For each included study, we explained significant concerns about other potential sources of bias not addressed in the above categories.Specifically, we sought a conflict of interest statement and a funding source.None of the studies reported any other bias risk.

Meta-analysis
The meta-analysis results depicting the relationship between herbal interventions and HPV infection in women were presented as a forest plot.All included studies reported an association between herbal interventions and testing negative for HPV after the application to individuals initially testing positive.The measurements of the relationship between HPV and herbal treatments in the selected studies varied between 0.23 (95%CI 0.03-2.12)and 17.00 (95%CI 3.46-83.44).These studies showed a significant degree of heterogeneity (I2:76, p=0.002).According to the fixed-effects model, the pooled OR was 1.86 (95%CI 0.64, 5.43).Among the five studies, three demonstrated a significant relationship between herbal treatment and HPV infection (Figure 2a).

DISCUSSION
This systematic review and meta-analysis delved into the efficacy of herbal treatments on cervicovaginal HPV infection.According to the meta-analysis results, herbal treatments were found to be effective in treating HPV infection.Furthermore, secondary outcomes indicated the effectiveness Herbal treatments on cervicovaginal human papillomavirus infection of herbal treatments in terms of ASCUS.However, they did not show a significant effect in regressing lesions concerning LSIL.
While HPV infection can be treated with invasive methods 14 , there is a substantial need for acceptable, safe, cost-effective, and non-surgical treatments to prevent cervical cancer.Herbal treatments emerge as one of these non-invasive methods 15,16 .In this study, herbal treatments were determined to be effective in clearing HPV infection (p=0.05).Although there is no meta-analysis specifically evaluating the effectiveness of herbal treatments in HPV treatment in the literature, a meta-analysis found a significant impact of biological and herbal studies on HPV clearance in a subgroup analysis similar to this study (p=0.01) 11.
A literature search identified meta-analysis studies evaluating the efficacy of non-surgical treatments on HPV.The results, similar to this study, indicated a significant effect on clearing HPV: Xiong et al. 10 (p<0.00001),Huang et al. 5 (p <0.0001), and Zhuang and Yang 11 (p<0.01).While these studies are up-to-date, providing a comprehensive assessment of non-surgical treatment methods, this study is crucial for focusing exclusively on the impact of herbal treatments and obtaining more specific data.
This study evaluated the regression of ASCUS and LSIL with herbal treatment methods as a secondary outcome.A regression in lesions concerning ASCUS was determined with herbal treatments (p=0.04).However, a significant effect concerning LSIL (p=0.51) could not be determined.In their subgroup analysis of a meta-analysis, Xiong et al. 5 found a significant impact of biological and herbal studies on cytological regression similar to this study (p=0.02).The same study found the overall effectiveness of non-surgical treatments on cytological regression to be significant (p=0.001).In a meta-analysis 15 , it was determined that non-surgical treatment methods had a significantly higher level of regression in mild abnormal cytology compared with the control group (p<0.00001).The inability to obtain significant results regarding LSIL in this study may be due to the limited number of studies considered for evaluation.

Strengths and limitations
One of the robust aspects of this study is that this is the first meta-analysis examining the efficacy of herbal treatments on HPV infection.The study aimed to provide less heterogeneous data by solely analyzing herbal treatments, contributing valuable insights to the field and literature.Another strength lies in the diverse participant background, with individuals from studies representing various income levels and different advantage-disadvantage groups, enhancing the generalizability of the findings.
The study's meticulous approach to scanning multiple databases and involving multiple researchers in the data extraction process ensures low bias and error.In addition, the methodological quality of the included studies was collaboratively assessed independently by each researcher, reaching a consensus after individual evaluations.However, one notable limitation is the inclusion of only English or Turkish publications, potentially excluding relevant studies published in other languages.

CONCLUSION
According to the meta-analysis results, herbal treatments demonstrated a reduction in HPV infections.While herbal treatments were effective in decreasing atypical squamous cells of undetermined significance, no significant impact was observed in the regression of low-grade squamous intraepithelial lesions.Nevertheless, further meta-analyses considering the effectiveness of herbal treatments require more RCTs to draw a more conclusive result.
Participant (P): Women with cervicovaginal HPV infection.Intervention (I): Herbal interventions, including (1) oral polyphenon E; (2) curcumin vaginal capsule; (3) vaginal spray containing olive oil; (4) myrtle vaginal suppository; (5) oral epigallocatechin gallate (EGCG); and (6) their combinations.Comparison (C): Comparison with a placebo or a group not receiving any treatment.Outcomes (O): (1) Results related to the effectiveness of herbal treatments on the treatment of HPV infection and (2) results related to the effectiveness of herbal treatments on cytological regression.Study Design (S): Experimental randomized controlled studies published in English and Turkish until December 2023 were included.

Figure 1
Figure 1 presents the PRISMA flowchart summarizing the literature search and study selection process.The remaining

Figure 1 .
Figure 1.Preferred reporting items for systematic reviews and meta-analysis 2020 flow diagram for new systematic reviews which included searches of databases and registers only.

Figure 2 .
Figure 2. Forest plots showing the association between herbal treatment and (a) negative human papillomavirus, (b) positive human papillomavirus, (c) Atypical squamous cells rate, and (d) Low grade squamous intraepithelial lesions rate.

Table 1 .
Features of the included studies.
RCT: randomized control trials; N/A: data not reported.