Human papillomavirus vaccine to prevent cervical intraepithelial neoplasia in Japan: A nationwide case-control study

Diagnostic value of HPV E6/E7 mRNA in screening for cervical intraepithelial neoplasia grade 2 or worse: A systematic review and meta‑analysis

Histology is considered the gold standard for diagnosing the pathological progress of cervical cancer development, while cervical intraepithelial neoplasia of grade 2 or worse (CIN2+) is the cutoff for intervention in clinical practice. The diagnostic value of human papillomavirus (HPV) E6/E7 mRNA in screening for CIN2+ has not been systematically summarized. A meta-analysis was conducted as part of the present study conducted to explore the diagnostic value of HPV E6/E7 mRNA in screening for CIN2+, aiming to provide a new marker for earlier clinical diagnosis of cervical cancer. The PubMed, Embase and Cochrane Library databases were searched from inception to May 2023. Studies reporting the true positive, false positive, true negative and false negative values in differentiating between CIN2+ and CIN2- were included, while duplicate publications, studies without full text, incomplete information or inability to conduct data extraction, animal experiments, reviews and systematic reviews were excluded. STATA software was used to analyze the data. A total of 2,224 patients were included of whom there were 1,274 patients with CIN2+ and 950 patients with CIN2-. The pooled sensitivity and specificity of the studies overall were 0.89 (95% CI, 0.84-0.92) and 0.59 (95% CI, 0.46-0.71), respectively; the positive likelihood ratio (LR) and the negative LR of the studies overall were 2.31 (95% CI, 1.61-3.32) and 0.21 (95% CI, 0.14-0.30), respectively. The pooled diagnostic odds ratio of the studies overall was 11.53 (95% CI, 6.85-19.36). Additionally, the area under the curve was 0.88. The analysis indicated that HPV E6/E7 mRNA has high diagnostic efficacy for CIN2+. HPV E6/E7 mRNA is highly sensitive in the diagnosis of CIN2+, which helps to reduce the rate of missed diagnoses. However, lower specificity may lead to a higher number of misdiagnoses in healthy patients.

Effectiveness of prophylactic HPV vaccines against cervical abnormalities and HPV infection in Japan: The J-HERS 2021 multicenter study

This study investigated the efficacy of the prophylactic human papillomavirus (HPV) vaccine, which was initiated between 2009 and 2013 in Japan. The study involved 1529 eligible women aged 16-39 years who visited 11 outpatient clinics in Japan for various reasons. These patients underwent HPV genotype analysis and a Pap test of cervical cell samples. A total of 299 women (19.6%) had received the prophylactic HPV vaccine (bivalent:quadrivalent vaccine ratio = 2:1). Of the 5062 participants in the Japanese Human Papillomavirus Disease Education and Research Survey (J-HERS 2011), which was conducted in the pre-vaccination era, 3236 eligible participants were included as controls. In this study (J-HERS 2021), the highest rate of HPV vaccination (53%) was observed in patients aged 22-27 years. Vaccinated individuals exhibited a 49% rate of protection against low-grade intraepithelial lesions (LSILs) and atypical squamous cells, not excluding high-grade squamous intraepithelial lesions (ASCH) or worse (LSIL/ASCH+), and a 100% rate of protection against high-grade squamous intraepithelial lesions (HSILs) or worse (HSIL+). Significant reductions in HPV16 (95%) and HPV18 (100%) infections were noted, but no differences were observed in HPV6 and HPV11 infections. The prevalences of HPV51 and HPV59 increased with vaccination, although these changes were not confirmed in the comparative study with J-HERS 2011. Comparing the prevaccination (J-HERS 2011) and postvaccination (J-HERS 2021) periods, 43%, 51%, 88%, and 62% reductions in HPV16, HPV18, HPV16/18, and HPV31/58 infection rates were observed, respectively. Similarly, 62% and 71% reductions in LSIL/ASCH+ and HSIL+ rates were noted, respectively. There were 88% and 87% reductions in LSIL/ASCH+ and HSIL+ rates in 16-21- and 28-33-year-old patients, respectively. Bivalent or quadrivalent vaccines provided 100% protection against high-grade squamous cell lesions (suggestive of CIN2 or CIN3) in young women aged <39 years at 9-12 years after initiation of Japan's first nationwide HPV vaccination program. Cross-protection against HPV31 and HPV58 is likely to occur, although some HPV-type replacements are inconsistent across vaccination regimens. This demonstrates the effectiveness of the HPV vaccine. However, continuous monitoring of cervical cancer and precancer is necessary in younger generations (born 1997-2007), who were rarely vaccinated due to the prolonged suspension of the vaccine recommendations in Japan.

Human papillomavirus vaccine impact on invasive cervical cancer in Japan: Preliminary results from cancer statistics and the MINT study

The first prophylactic vaccine against human papillomavirus (HPV) 16 and HPV18 was licensed in Japan in 2009. HPV vaccine effectiveness against high-grade cervical lesions has been demonstrated among young Japanese women, but evidence of its effects on invasive cervical cancer (ICC) is lacking. Using data from two different cancer registries, we compared recent trends of new ICC cases by age group using Poisson regression analysis. We also analyzed time trends in HPV16/18 prevalence among 1414 Japanese women aged <40 years newly diagnosed with ICC in the past decade. Based on the population-based cancer registry, the incidence of ICC among young women aged 20-29 years showed a significant decline from 3.6 to 2.8 per 100 000 women-years during 2016-2019, but no similar decline was observed for older age groups (p < 0.01). Similarly, using data from the gynecological cancer registry of the Japan Society of Obstetrics and Gynecology, the annual number of ICCs among women aged 20-29 years also decreased from 256 cases to 135 cases during 2011-2020 (p < 0.0001). Furthermore, a declining trend in HPV16/18 prevalence in ICC was observed only among women aged 20-29 years during 2017-2022 (90.5%-64.7%, p = 0.05; Cochran-Armitage trend test). This is the first report to suggest population-level effects of HPV vaccination on ICC in Japan. Although the declining trend in HPV16/18 prevalence among young women with ICC supports a causal linkage between vaccination and results from cancer registries, further studies are warranted to confirm that our findings are attributable to vaccination.

Evaluation of the Therapeutic Effect of Quadrivalent Human Papillomavirus (HPV) Vaccination on Cervical Intraepithelial Neoplasia Lesions

Cervical cancer is the most common health problem among global young women. Cervical intraepithelial neoplasia (CIN) is a pre-invasive stage of cervical cancer, the major cause of which is human papillomavirus (HPV), and vaccination has a promising effect on reducing the progression of CIN lesions. The current study was a retrospective case control investigation in two centers, Shiraz and Sari Universities of Medical Sciences from 2018 to 2020 to evaluate the effect of quadrivalent HPV vaccination on CIN lesions (I, II, and III). Eligible patients diagnosed with CIN were selected and divided into two groups: one group received HPV vaccine and the control group did not. The patients were followed up after 12 and 24 months. The information about tests (e.g., Pap smear, colposcopy, and pathology biopsy) and history of vaccination was recorded and statistically analyzed. 150 patients were classified into the control group (without HPV vaccination) and the other 150 patients were in the Gardasil group (with HPV vaccination). The patients' mean age was 32 years old. Two groups were not significantly different according to age and CIN grades. Between two groups in 1 and 2 years' follow-up examinations, the high-grade lesions in both Pap smear and pathology were significantly diminished in patients in the HPV vaccinated group in comparison with the control group with p-values 0.001 and 0.004 in 1 year follow-up respectively and 0.00 after 2 years follow-up. HPV vaccination can prevent the progression of CIN lesions in 2-year follow-up examination.

Diagnosis Assistance in Colposcopy by Segmenting Acetowhite Epithelium Using U-Net with Images before and after Acetic Acid Solution Application

Colposcopy is an essential examination tool to identify cervical intraepithelial neoplasia (CIN), a precancerous lesion of the uterine cervix, and to sample its tissues for histological examination. In colposcopy, gynecologists visually identify the lesion highlighted by applying an acetic acid solution to the cervix using a magnifying glass. This paper proposes a deep learning method to aid the colposcopic diagnosis of CIN by segmenting lesions. In this method, to segment the lesion effectively, the colposcopic images taken before acetic acid solution application were input to the deep learning network, U-Net, for lesion segmentation with the images taken following acetic acid solution application. We conducted experiments using 30 actual colposcopic images of acetowhite epithelium, one of the representative types of CIN. As a result, it was confirmed that accuracy, precision, and F1 scores, which were 0.894, 0.837, and 0.834, respectively, were significantly better when images taken before and after acetic acid solution application were used than when only images taken after acetic acid solution application were used (0.882, 0.823, and 0.823, respectively). This result indicates that the image taken before acetic acid solution application is helpful for accurately segmenting the CIN in deep learning.

Disparities among Japanese municipalities in recommendations for routine and catch-up HPV vaccinations

In November 2021, the government of Japan announced a reversal of its decision in 2013 to suspend the previous proactive recommendation for HPV vaccination. However, the program for young girls to receive routine and catch-up vaccinations has not necessarily developed as expected. We conducted a nationwide questionnaire survey by mail in September 2022. The survey was mailed to 133 municipalities consisting of all cities/wards of the Tokyo and Osaka Prefectures and all other prefectural capital cities. Responses were received from 82 municipalities (62.7%). Notification of routine HPV vaccinations had already been sent to 76 (92.7%) of the municipalities; 70 (85.4%) had been encouraged to promote catch-up vaccinations. The questionnaire forms for registration and pre-vaccination screening for routine immunization had been sent to 74.1% (60/81) of the municipalities and 68.8% (55/80) for catch-up immunizations. For catch-up vaccination, only 54 municipalities (65.9%) had detailed vaccination records for those eligible. In total, 10 municipalities (12.2%) had virtually no vaccination records because these had already been discarded. In addition, 61 municipalities (74.4%) had notified only women and girls eligible for a catch-up vaccination based on their vaccination record, whereas 25.6% (21/82) of the municipalities reported that they had sent, or would send, the notification to all women and girls within the targeted grades, including those who had already been vaccinated with three injections. The survey revealed disparities among the municipalities in their HPV vaccine notification processes. Future research on monitoring HPV vaccination rates and incidence rates of cervical cancer and precancerous lesions in each municipality will be desirable.

Survey of pediatricians concerning the human papillomavirus vaccine in Japan: Positive attitudes toward vaccination during the period of proactive recommendation being withheld

In 2013, the human papillomavirus (HPV) vaccine was introduced as a national immunization program in Japan. However, because of a wide range of symptoms after vaccination, the Japanese Ministry of Health, Labor and Welfare decided to withhold proactive recommendations, a situation that has continued for more than eight years. During the withholding, absent any scientific or epidemiological evidence to support a relationship between HPV vaccines and symptoms, we surveyed pediatricians at Osaka Pediatric Association and analyzed the changing of attitudes in 2020 (n = 200) and 2021 (n = 190). A total of 44.5% respondents in 2020 and 67.9% in 2021 offered HPV vaccination to targets at the time the questionnaire was administered, indicating that the rate of pediatricians providing vaccines had increased significantly (p < .001). A total of 74.0% of respondents in 2020 and 77.9% in 2021 had a positive opinion of HPV vaccination (p = .369), and 64.3% in 2020 and 78.3% in 2021 were "not at all concerned or had almost no concern" about HPV vaccination (p = .002). These results suggest that, in general, most physicians who are primarily responsible for HPV vaccination in a given field had a positive attitude toward vaccination during the proactive recommendation having been withheld.

A cross-sectional survey on awareness of cancer risk factors, information sources and health behaviors for cancer prevention in Japan

Due to recent increases in cancer burden worldwide, we investigated current awareness of cancer risk factors and the association between information sources and health behaviors for cancer prevention in Japan. A nationwide representative sample aged 20 years or older (563 men and 653 women) responded to a questionnaire as part of a population-based survey in December 2018. Tobacco smoking (55.7% of the mean attributable fraction of cancer risk overall) and cancer-causing infection (52.0%) were regarded more highly than other lifestyle factors as causes of cancer (obesity [36.6%], physical inactivity [31.9%], unbalanced diet [30.9%], and alcohol consumption [26.2%]). The association between information sources and health behaviors for cancer prevention was evaluated using a logistic regression model. The websites of public institutions, and health professionals were associated with a broad range of health behaviors including improving diet, exercise, cancer screening/health check-up, and abstinence from smoking/drinking. Among sources of print media, positive associations were observed between books and improving diet/exercise, brochures and cancer screening/health check-up, and advertisements and abstinence from smoking/drinking. A strategic health communication approach that utilizes various information sources and delivery channels is needed to inform the public about cancer prevention and to motivate risk-reducing behaviors in the population.

Effectiveness of HPV vaccine against cervical precancer in Japan: multivariate analyses adjusted for sexual activity

Japanese girls aged 12–16 years are offered free human papillomavirus (HPV) vaccination and cervical cancer screening is conducted with cytology and not HPV testing from the age of 20 years. So far, no study has analyzed the effect of HPV vaccination against cervical precancers considering HPV infection status and sexual activity. We aimed to analyze the vaccine effectiveness (VE) against HPV infection and cytological abnormalities, adjusted for sexual activity. This study comprised women aged 20–26 years who underwent cervical screening in Niigata. We obtained HPV vaccination status from municipal records and a questionnaire along with information concerning sexual activity. Of 5194 women registered for this study, final analyses included 3167 women in the vaccinated group (2821 vaccinated women prior to sexual debut) and 1386 women in the unvaccinated group. HPV 16/18 (0.2% vs 3.5%), 31/45/52 (3.4% vs 6.6%), and 31/33/45/52/58 (5.0% vs 9.3%) positive rates were significantly lower in the vaccinated group (P < 0.001). No women vaccinated before sexual debut had HPV 16/18‐related cytological abnormalities. VE for HPV 16/18 infection and high‐grade cytological abnormalities in women vaccinated prior to sexual debut were 95.8% (95% CI 81.9–99.0%; P < 0.001) and 78.3% (95% CI 11.3–94.7%; P = 0.033), respectively, in multivariate analyses adjusted for age and number of sexual partners. However, analyses of all vaccinated women did not show significant effectiveness against cytological abnormalities. Our results showed the effectiveness of HPV vaccine against high‐grade cervical cytological abnormalities and the importance of the vaccination before sexual debut.

Changes in HPV16/18 Prevalence among Unvaccinated Women with Cervical Intraepithelial Neoplasia in Japan: Assessment of Herd Effects following the HPV Vaccination Program

Since the human papillomavirus (HPV) vaccination program for Japanese girls aged 12–16 years began in 2010, vaccination uptake has been low in women born before 1993 but high (approximately 70%) in those born during 1994–1999. We previously compared the prevalence of vaccine types HPV16 and HPV18 in cervical intraepithelial neoplasia grade 1–3 (CIN1–3) or adenocarcinoma in situ (AIS) between vaccinated and unvaccinated cohorts and found direct protection effects among vaccinated women in Japan. In this study, we focused on changes in HPV16/18 prevalence among “unvaccinated” cohorts with CIN/AIS. We analyzed HPV16/18 prevalence among 5051 unvaccinated women aged <40 years, newly diagnosed with CIN/AIS during 2012–2021 for time trends. Declining trends in HPV16/18 prevalence over 9 years were observed in CIN1 (36.0–10.0%, Ptrend = 0.03) and CIN2–3/AIS (62.5–36.4%, Ptrend = 0.07) among women aged <25 years. HPV16/18 prevalence in CIN1 and CIN2–3/AIS diagnosed at age 20–24 years was lower in 1994–1999 birth cohorts compared with 1988–1993 birth cohorts (4.5% vs. 25.7% for CIN1 and 40.0% vs. 58.1% for CIN2–3/AIS, both p = 0.04). Significant reduction in HPV16/18 prevalence among young unvaccinated women with CIN1 and CIN2–3/AIS suggests herd effects of HPV vaccination in Japan.

International comparison of trends in cancer mortality: Japan has fallen behind in screening-related cancers

While the age-standardized mortality rate in Japan is decreasing for all cancers as a whole, this is not the case for some major site-specific cancers. We descriptively compared trends in all-cancer and site-specific cancer mortality in Japan and selected countries. Data on age-standardized cancer mortality rates in six countries (Japan, the USA, the UK, Canada, Australia and the Republic of Korea) in 1980-2016 were obtained from the World Health Organization mortality database. While stomach and liver cancer mortality rates in Japan and Korea were initially much higher than those in non-Asian countries, they have rapidly decreased over the long term. By contrast, colorectal, pancreatic and cervical cancer mortality rates in Japan, which were initially lower than those in other countries, have increased such that they are now similar or higher than the rates in non-Asian countries. For male lung cancer, Japan's initially lower mortality rate is now comparable to that in non-Asian countries as a result of slower decline. Meanwhile, the mortality rate of female breast cancer in Japan and Korea has increased and is nearing the rates observed in non-Asian countries, which by contrast have shown a steady decrease. Thus, while Japan has been successful in reducing the burden of stomach and liver cancers, it is falling behind in reducing the mortality rate of screening-related cancers such as colorectal, female breast and cervical cancers. Control measures for these cancers need to be strengthened.

Cervical Cancer Protection in Japan: Where Are We?

In Japan, government subsidies for human papillomavirus (HPV) vaccination of girls aged 13–16 commenced in 2010. By early 2013, vaccination had become a widely accepted national immunization program. However, in June of 2013, the Ministry of Health, Labor, and Welfare (MHLW), the government’s lead agency, suspended its recommendation for vaccination in response to reports of adverse vaccine events. The rate of HPV vaccination quickly dropped from 70% to almost zero, where it has lingered for eight years. In 2020, a new 9-valent HPV vaccine was licensed in Japan. The momentum seemed to be building for the resumption of HPV vaccinations, yet Japanese mothers remain widely hesitant about vaccinating their daughters, despite the well-proven safety and efficacy of the HPV vaccines. The Japanese government and our educational and medical institutions must work harder as a team to inform our parents and their children about the life-saving benefits of the HPV vaccine, and at the same time, we must respond to all their concerns and questions. The vaccine hesitancy of unvaccinated women born in 2000 and thereafter is a natural consequence of the suspension of the government‘s recommendation. We must also take every possible measure to reduce the significant risk for cervical cancer these women have.

A nationwide birth year-by-year analysis of effectiveness of HPV vaccine in Japan

In Japan, the age‐adjusted incidence of cervical cancer has been increasing constantly and rapidly among younger women. We set out to accurately confirm the effectiveness of the HPV vaccine in Japan. Data were collected for women born in the fiscal year (FY) 1990 to 1997, who became eligible for their 20‐y‐old cervical cancer screening between the FY 2010 to 2017. The adjusted incidence of cervical intraepithelial neoplasia (CIN)1+ in women born in FY 1990 to 1993, that is those who reached the national vaccination target age prior to the introduction of publicly subsidized HPV vaccinations, referred here after as “the pre‐introduction generation”, was 1.42% (242/17 040). The incidence in the “vaccination generation” (women born in FY 1994 to 1997, that is those who were heavily vaccinated as a group when they were of the nationally targeted age of 13‐16) was 1.66% (135/8020). There was no significant difference between these incidence rates. However, our FY birth year‐by‐year analysis revealed that the incidence of CIN1+ was obviously lower than that predicted based on just the trend for CIN1+ seen in the pre‐introduction generation. Our analysis revealed that the incidence of CIN3+ was obviously lower in the vaccination generation than in the pre‐introduction generation (P = .0008). The incidence of CIN was already tending to increase in both the pre‐introduction and vaccination generations. The changes in CIN incidence by individual birth FY must be examined to accurately determine the actual effects of the HPV vaccine for reducing mild cervical lesions.

Prevalence and Risk Factors of Human Papillomavirus Infection among Japanese Female People: A Nationwide Epidemiological Survey by Self-Sampling

Background:

Nationwide epidemiological surveys of behavioral factors and human papillomavirus (HPV) infection among Japanese women are scarce. This study aimed to determine the prevalence, genotype distribution, and significant predictive factors of HPV infection using self-collected vaginal samples from Japanese female people.

Methods:

The study population consisted of 1,050 female subjects aged 16–75 years (median 30 years). The participants were asked to provide self-collected samples from the vaginal wall using cotton swabs for genotyping of HPV. We compared the participants’ characteristics and detected HPV genotypes to determine significant predictors of HPV infection.

Results:

After excluding 47 participants (34 participants of unknown age, 11 virgin participants, 1 participant who engaged in sex with another woman, and 1 participant who did not undergo β-globin detection), 1,003 participants were included in the analysis. Of the 1,003 participants, 426 (42.5%) participants had at least one HPV genotype, 282 (28.1%) participants had high-risk HPV genotypes, 306 (30.5%) had low-risk HPV genotypes, and 162 (16.2%) participants had both HPV genotypes. HPV-16/18 positivity was found in 5.4% (54/1,003) participants. The most frequently detected high-risk HPV genotype was HPV-52 (86/1,003; 8.6% participants). The number of lifetime sex partners (≥6) and a present history of sexually transmitted infection (STI) were significant predictors of high-risk HPV infection. The number of lifetime sex partners (≥6), age of coitarche (≥20 years of age), unmarried status, and a present history of STI were significant predictors of low-risk HPV infection.

Conclusions:

The prevalence of high-risk and low-risk HPV infection among Japanese female subjects was 28.1% and 30.5%, respectively. The number of lifetime sex partners (≥6) and present history of sexually transmitted infection were the common significant predictors of high-risk and low-risk HPV infection.

Internet Survey of Awareness and Behavior Related to HPV Vaccination in Japan

Recommendations for HPV vaccines were suspended in 2013 due to unfounded safety fears in Japan. We aimed to clarify the differences between vaccinated and unvaccinated females in their awareness, knowledge, and behaviors toward cervical cancer, HPV vaccination and sex. Questionnaires were administered online to women aged 16 to 20. We conducted investigations for the following: awareness, knowledge, and actions for cervical cancer, HPV vaccination, and sexual activity, as well as items related to participants’ social background. The survey in 828 girls revealed three points. The first is that more than half of the surveyed Japanese girls had poor knowledge about cervical cancer screening, HPV, or HPV vaccines. The second is that those in the unvaccinated group had a particularly poor knowledge of the subject and tended to have higher sexual activity. The final is that only 0.5% of the girls experienced changes in awareness about sexual activity after vaccination. In conclusion, this is the first large-scale survey analyzing the association between HPV vaccination and sexual activity in Japanese girls. Not only do unvaccinated girls not benefit from vaccines, but they also tend to engage in high-risk sexual behavior, and thus it is even more important to provide information on the effectiveness of vaccines and the usefulness of cancer screening.

Human papillomavirus vaccine to prevent cervical intraepithelial neoplasia in Japan: A nationwide case-control study

Cervical cancer remains among the most common cancers in women worldwide and can be prevented by vaccination. The Ministry of Health, Labour and Welfare of Japan suspended active recommendation of regular human papillomavirus (HPV) vaccines in 2013 because of various symptoms including chronic pain and motor impairment. This nationwide case-control study from April 2013 to March 2017 targeted women aged 20-24 years old at cervical screening. We compared HPV vaccination exposure between those with abnormal and normal cytology. Abnormal cytology was classified based on the results of histological test and we calculated the odds ratio (OR) and 95% confidence interval (CI) of the above endpoints and vaccination exposure using the conditional logistic regression model and estimated vaccine effectiveness using the formula (1 - OR) × 100. A total of 2483 cases and 12 296 controls (one-to-five matching) were eligible in 31 municipalities in Japan. The distribution of histological abnormalities among cases was 797 CIN1 (including dysplasia) (32.1%), 165 CIN2 (6.7%), 44 CIN3 (1.8%), and eight squamous cell carcinoma (SCC) (0.3%). The OR of HPV vaccination compared with no vaccination for abnormal cytology, CIN1+, CIN2+, and CIN3+ versus controls was 0.42 (95% CI, 0.34-0.50), 0.42 (95% CI, 0.31-0.58), 0.25 (95% CI, 0.12-0.54), and 0.19 (95% CI, 0.03-1.15), respectively, equating to a vaccine effectiveness of 58.5%, 57.9%, 74.8%, and 80.9%, respectively. Eight patients had SCC, none was vaccinated. This nationwide case-control study in Japan demonstrated a substantial risk reduction in abnormal cytology and CIN among women who did versus those who did not receive HPV vaccination.