Epidemiology and Health

A meta-analysis of the association between adolescent pregnancy and the risk of gynecological cancers

OBJECTIVES: Despite several investigations, the association between adolescent pregnancy and gynecological cancers has yet to be conclusively established. To further explore this association, we conducted a meta-analysis of observational studies.METHODS: We conducted a comprehensive search of databases such as PubMed, Web of Science, and Scopus to identify studies investigating the link between adolescent pregnancy and gynecologic cancers. This search continued until February 20, 2023. To assess the heterogeneity among the studies, we used the I2-statistics. We also explored the potential presence of publication bias using the Begg and Egger tests. The overall effect sizes were reported as either risk ratio or odds ratio, accompanied by a 95% confidence interval (CI), using a random-effects model.RESULTS: From an initial pool of 25,436 studies, a total of 76 studies involving 13,991,683 participants met the predefined eligibility criteria. The analysis indicated that the overall effect size for individuals having their first pregnancy at age 20 or older, compared to those having it before age 20, was 0.54 (95% CI, 0.50 to 0.59) for cervical cancer, 0.82 (95% CI, 0.77 to 0.88) for ovarian cancer, and 0.96 (95% CI, 0.89 to 1.04) for uterine cancer.CONCLUSIONS: Our findings suggest that experiencing one’s initial pregnancy at the age of 20 or above is associated with a significantly reduced risk of cervical and ovarian cancer. However, no significant association was found between first pregnancy at this age and uterine cancer.

Changes in metabolic syndrome and the risk of breast and endometrial cancer according to menopause in Korean women

OBJECTIVES: This study investigated how changes in metabolic syndrome (MetS) are associated with the subsequent risk of breast and endometrial cancer according to menopausal status.METHODS: This cohort study, using data from the National Health Insurance Service database, included women aged ≥40 years who underwent 2 biennial cancer screenings (2009-2010 and 2011-2012) and were followed up until 2020. Participants were grouped into MetS-free, MetS-recovery, MetS-development, and MetS-persistent groups. Menopausal status (premenopausal, perimenopausal, and postmenopausal) was assessed at 2 screenings. Cox proportional hazard regression was used to assess the association between MetS changes and cancer risk.RESULTS: In 3,031,980 women, breast and endometrial cancers were detected in 39,184 and 4,298, respectively. Compared with the MetS-free group, those who recovered, developed, or had persistent MetS showed an increased risk of breast cancer, with adjusted hazard ratios (aHRs) of 1.05, 1.05, and 1.11, respectively (p<0.005). MetS persistence was associated with an increased risk of breast cancer in postmenopausal women (aHR, 1.12, 95% confidence interval [CI], 1.08 to 1.16) but not in premenopausal or perimenopausal women. MetS persistence was associated with an increased risk of endometrial cancer in premenopausal, perimenopausal, and postmenopausal women, with aHRs of 1.41 (95% CI, 1.17 to 1.70), 1.59 (95% CI, 1.19 to 2.12), and 1.47 (95% CI, 1.32 to 1.63), respectively.CONCLUSIONS: Increased breast cancer risk was associated with recovered, developed, and persistent MetS in postmenopausal women. Meanwhile, increased endometrial cancer risk was found in obese women who recovered from MetS or persistently had MetS, regardless of menopausal status, when compared to MetS-free women.

Socioeconomic factors affecting breast and cervical cancer screening compliance in Asian National Cancer Centers Alliance countries: a systematic review

Breast and cervical cancers are the most frequently diagnosed cancers in women. The Asian National Cancer Centers Alliance (ANCCA) has strengthened cancer control efforts in the Asia region; however, only a few countries have achieved sufficient participation rates. This systematic review aimed to synthesize the existing evidence on socioeconomic factors influencing women’s compliance with breast and cervical cancer screening in ANCCA countries. This study was conducted as a systematic review, with studies collected from PubMed, Cochrane Library, Scopus, and Embase. All included studies employed cross-sectional designs to identify socioeconomic factors affecting compliance with breast or cervical cancer screening. Study selection, quality assessment, and data extraction were carried out by 2 independent reviewers with cross-checking. In total, 48 studies were reviewed. Education level and family history were associated with participation in breast cancer screening, while education level, household income, marital status, and medical insurance were linked with cervical cancer screening. When stratified by Human Development Index (HDI) level or by the presence of a National Cancer Screening Program, differences were observed in the factors influencing screening compliance. Nevertheless, higher education consistently correlated with higher screening rates for both cancer types, regardless of HDI level. This systematic review identified multiple socioeconomic factors that shape breast and cervical cancer screening compliance in Asian countries. To reduce disparities in participation, tailored multi-strategy approaches adapted to each country’s specific context are required. These findings may provide useful evidence for future research and policy initiatives aimed at addressing health equity issues.

Parental intention to vaccinate daughters with the human papillomavirus vaccine in Korea: a nationwide cross-sectional survey

OBJECTIVES: We aimed to identify and compare the characteristics and factors associated with parental intention to vaccinate daughters under 12 years old against human papillomavirus (HPV), examining data from 2016 and 2020.METHODS: Data were obtained from the Korean National Cancer Screening Survey conducted in 2016 and 2020. The present study included 3,510 parents with daughters under 12 years old. Changes in parental intention-to-vaccinate rates were calculated. To identify factors associated with parental intention to vaccinate their daughters, the chi-square test and logistic regression analysis were used.RESULTS: The percentage of respondents intending to vaccinate their daughters increased from 33.4% in 2016 to 58.9% in 2020, constituting a 25.5 percentage point (%p) increase. Since 2016, the proportion of men expressing positive intention towards HPV vaccination increased by 31.5%p, while that of women demonstrated a 20.9%p increase. Logistic regression analysis indicated that parents with a strong intention to vaccinate their daughters tended to be younger, more educated, and aware of the free vaccination program available, as well as to have a history of HPV vaccination and to have undergone cervical cancer screening within 2 years, compared to those who did not intend to vaccinate. Being a mother with a history of HPV vaccination was the strongest predictor of positive intention to vaccinate a daughter.CONCLUSIONS: The intention among parents to vaccinate daughters remains relatively low, although it is rising. To increase the HPV vaccination rate, strong recommendations and education should be provided to parents and the younger generation.

Incidence and mortality of cervical cancer in Vietnam and South Korea (1999-2017)

Cervical cancer is a major disease burden in Vietnam. This study aimed to estimate the incidence and mortality rates of cervical cancer in Vietnam (1999-2017) in comparison to those in Korea, where a population-based cancer registry and national cervical cancer screening program have been implemented. The estimated incidence and mortality of cervical cancer in Vietnam and Korea (1999-2017) were collected from Global Burden of Disease 2017 study. Estimated age-standardized rates (ASRs) in both countries were calculated utilizing the 1999-2017 population of each country and the World Health Organization standard population. The reported ASRs in Korea were also computed using data on incidence and mortality (1999-2017) and the Korean population from the Korea Statistical Information Service. In Vietnam, the estimated incidence and mortality of cervical cancer decreased annually by 0.84% and 1.01%. In Korea, the trend of reported incidence showed a dramatic drop (1999-2007 annual percent change [APC], -4.53%) before stably declining (2007-2017 APC, -2.71%). Reported mortality also significantly decreased (2003-2008 APC, -6.63%), and then maintained a stable decline (2008-2017 APC, -3.78%). The incidence and mortality rates were higher in Vietnam than in Korea. The declining trend of incidence and mortality in Vietnam was slower than the corresponding trends in Korea. A national screening program should be implemented for Vietnamese women aged over 30 to maintain, or even hasten, the decline in cervical cancer incidence and mortality. A population-based cancer registry may help monitor the effectiveness of a cervical cancer screening program.

Sociodemographic inequalities in the uptake of Papanicolaou tests in Peru: Analysis of the Demographic and Family Health Survey 2015-2017

This study was conducted to analyze the inequalities in Papanicolaou test (also referred to as the Pap smear) uptake according to the socio-demographic characteristics of Peruvian women 30 years to 59 years of age using information from the 2015-2017 Demographic and Family Health Survey (ENDES, acronym in Spanish). This is an analytical, cross-sectional study based on information acquired from the 2015-2017 ENDES surveys. Socio-demographic characteristics were reported using absolute frequencies and weighted proportions with 95% confidence intervals, considering results with a p-value <0.05 as statistically significant. Concentration curves (CCs) and concentration indices (IndCs) were created based on the interaction of the wealth index and uptake of Pap smears, taking into account the different characteristics of the population studied for the measure of inequalities. All the CCs were distributed below the line of equality. Similarly, all the IndCs were higher than zero, indicating inequality in the uptake of Pap smears, favoring those with a higher wealth index. The highest IndC values were obtained from women aged 50-59 (IndC, 0.293), those who lived in the jungle (IndC, 0.230), and those without health insurance (IndC, 0.173). We found socio-demographic inequalities in the uptake of Pap smears in Peru, favoring women with a higher wealth index. More funding is needed to promote cervical cancer screening programs and to create systems that ensure equal access to healthcare in Peru.

Human papillomavirus: footprints in the population of western India

OBJECTIVES: Cancer is a multi-factorial disease, with various intrinsic and environmental factors contributing to its occurrence. Human papillomavirus (HPV) has been associated with the occurrence of many cancers. India severely suffers from 3 HPV-associated cancers (cervical cancer, oral cancer, and oropharyngeal cancer). Hence, the present study aimed to evaluate the HPV burden in these 3 cancers among patients from the western region of India.METHODS: DNA was isolated from samples from 400 cervical cancer, 127 oral cancer, and 75 oropharyngeal cancer patients. Polymerase chain reaction was performed using degenerate primers for HPV infection.RESULTS: Overall, HPV infection was observed in 87% of cervical cancer cases, 12.5% of oral cancer cases, and 26.7% of oropharyngeal cancer cases when analyzed with a cumulative detection method using the MY 09/11, GP 5+/6+, and CP I/II primer sets.CONCLUSIONS: A significant prevalence of HPV infection was detected in all 3 cancers using the degenerate primer sets. This finding implies that testing for HPV infection using multiple primer sets is crucial for determining its actual prevalence in various malignancies.

Effect of Pap smears on the long-term survival of cervical cancer patients: a nationwide population-based cohort study in Korea

OBJECTIVES: This study aimed to investigate the effect of cervical cancer screening by Papanicolaou (Pap) smears on the long-term survival of cervical cancer patients.METHODS: We constructed a retrospective cohort of 14,903 women diagnosed with invasive cancer or carcinoma in situ in 2008 and 2009 and followed up until December 31, 2019, by using individual-level data from 3 national databases of the Korean National Cancer Screening Program, the Korean Central Cancer Registry, and death certificates. Cox proportional-hazards regression was used to investigate the effect of cervical cancer screening on mortality.RESULTS: In total, 12,987 out of 14,867 patients (87.4%) were alive at the end of the follow-up period (median: 10.5 years). Screened patients had a 38% lower risk of cervical cancer death than never-screened patients (hazard ratio [HR], 0.62; 95% confidence interval [CI], 0.54 to 0.70). Screening was associated with 59% and 35% lower risks of death, respectively, in screened patients with localized and regional stages. Furthermore, lower HRs among women who received screening were observed in all age groups, especially women aged 50–59 years (HR, 0.54; 95% CI, 0.42 to 0.69). The lowest HR for cervical cancer death was reported among patients screened within the past 2 years (HR, 0.54; 95% CI, 0.47 to 0.63), and the HRs increased with increasing time intervals.CONCLUSIONS: Pap smear screening significantly reduced the risk of cervical cancer-specific death in Korean women across all cancer stages.

Income-based disparities in the risk of distant-stage cervical cancer and 5-year mortality after the introduction of a National Cancer Screening Program in Korea

OBJECTIVES: This study assessed the socioeconomic gradient in the risk of distant-stage cervical cancer (CC) at presentation and 5-year mortality for new CC patients after the introduction of a national Cancer Screening Program (NCSP) in Korea.METHODS: All new CC cases from 2007 to 2017 were retrieved from the Korea Central Cancer Registry database linked with the National Health Information Database of the National Health Insurance Service. The age-standardized cumulative incidence of CC, adjusted odds ratios (ORs) of distant metastasis at presentation, and adjusted all-cause mortality hazard ratios (HRs) within 5 years post-diagnosis were assessed according to the income gradient.RESULTS: The 11-year age-standardized cumulative incidence of CC ranged from 48.9 to 381.5 per 100,000 women, with the richest quintile having the highest incidence. Of 31,391 new cases, 8.6% had distant metastasis on presentation, which was most frequent among Medical Aid beneficiaries (9.9%). Distant-stage CC was more likely when the income level was lower (OR, 1.46; 95% confidence interval [CI]), 1.28 to 1.67 for the lowest compared to the richest) and among Medical Aid beneficiaries (OR, 1.50; 95% CI, 1.24 to 1.82). The 5-year mortality was greater in the lower-income quintiles and Medical Aid beneficiaries than in the richest quintile.CONCLUSIONS: The incidence of CC was higher in the richest quintile than in the lower income quintiles, while the risk of distant-stage CC and mortality was higher for women in lower income quintiles in the context of the NCSP. A more focused approach is needed to further alleviate disparities in the timely diagnosis and treatment of CC.

The impact of COVID-19 on screening for colorectal, gastric, breast, and cervical cancer in Korea

OBJECTIVES: The coronavirus disease 2019 (COVID-19) pandemic has affected the utilization of healthcare services, including participation in cancer screening programs. We compared cancer screening participation rates for colorectal, gastric, breast, and cervical cancers among participants in the National Cancer Screening Program (NCSP) in 2019 and 2020 to address the potential distraction effect of COVID-19 on cancer screening.METHODS: Data from the NCSP for 4 cancer types (stomach, colorectal, breast, and cervical) in 2019 and 2020 were used to calculate cancer screening participation rates by calendar month, gender, age group, and geographical region. Monthly participation rates were analyzed per 1,000 eligible individuals.RESULTS: The screening participation rate decreased in 2020 compared to 2019 for all 4 cancers: colorectal (40.5 vs. 35.3%), gastric (61.9 vs. 54.6%), breast (63.8 vs. 55.8%), and cervical (57.8 vs. 52.2%) cancers. Following 2 major COVID-19 waves in March and December 2020, the participation rates in the 4 types of cancer screening dropped compared with those in 2019. The highest decline was observed in the elderly population aged 80 years and older (percentage change: -21% for colorectal cancer; -20% for gastric cancer; -26% for breast cancer; -20% for cervical cancer).CONCLUSIONS: After the 2 major COVID-19 waves, the screening participation rate for 4 types of cancer declined compared with 2019. Further studies are needed to identify the indirect effects of the COVID-19 pandemic on cancer patients, such as delayed diagnoses of cancer or excess cancer deaths.

Changes in cancer screening before and during COVID‐19: findings from the Korean National Cancer Screening Survey 2019 and 2020

OBJECTIVES: The coronavirus disease 2019 (COVID-19) pandemic has negatively affected every aspect of medical care. However, information regarding the impact of the pandemic on cancer screening is lacking. This study aimed to explore cancer screening changes by geographic region before and during the pandemic in Korea.METHODS: Korean National Cancer Screening Survey data for 2019 and 2020 were used. Changes in the screening rate before and during the COVID-19 pandemic were calculated by subtracting the rate in 2020 from the rate in 2019. Multivariate logistic regression analyses examined the differences in screening rates at the national and 16 provincial levels before and after the COVID-19 outbreak.RESULTS: The 1-year screening rates for the four types of cancer decreased during the pandemic (stomach cancer: -5.1, colorectal cancer: -3.8, breast cancer: -2.5, cervical cancer: -1.5%p). In metropolitan areas, the odds of undergoing screening tests during the pandemic were significantly lower than before the pandemic for stomach (adjusted odds ratio [aOR], 0.66; 95% confidence interval [CI], 0.56 to 0.76), colorectal (aOR, 0.63; 95% CI, 0.50 to 0.79), and breast cancers (aOR, 0.75; 95% CI, 0.60 to 0.94). Furthermore, the likelihood of undergoing stomach cancer screening during the pandemic was significantly lower than before the pandemic in non-metropolitan urban areas (aOR, 0.81; 95% CI, 0.70 to 0.94), while it was higher in rural areas (aOR, 1.54; 95% CI, 1.10 to 2.16).CONCLUSIONS: Since the COVID-19 pandemic, the cancer screening rate has decreased significantly, especially in large cities. Public health efforts are required to improve cancer screening rates.