Trends in the incidence rate and risk factors for breast cancer in Japan

The incidence rate of breast cancer in Japanrose more than two-fold from 1959–60 to 1983–87.To assess to what extent this increase canbe explained by changes in the prevalence offour major risk factors of breast cancer (i.e.age at menarche, age at first birth, ageat menopause, and parity), we estimated the probabilityof developing breast cancer based on the jointdistribution and relative risks of these four riskfactors. The age-specific incidence rate during 1959–60 reportedby the Miyagi Prefectural Cancer Registry was usedto estimate the baseline hazard rate for womenwithout the four risk factors in the sameage group. Assuming that the baseline hazard rateis constant during all periods, we calculated theexpected incidence rates during the periods of 1959–60,1962–64, 1968–71, 1973–77, 1978–81, and 1983–87 for eachage group. Large discrepancies were noted between theobserved and expected incidence rates during 1983–87 inall age groups. The change in the jointdistribution of the four risk factors accounted forless than 40% of the increase observed from1959–60 to 1983–87, suggesting the effects of otherpowerful risk factors.     

Ethnic differences in the incidence of cancer in Norway

Traditionally there have been differences in cancer incidence across geographic regions. When immigrants have moved from low‐income to high‐income countries, their incidence have changed as they have adapted to the lifestyle in the new host country. Given worldwide changes in lifestyle factors over time, we decided to examine cancer incidence in immigrant groups in Norway, a country with a recent immigration history, complete cancer registration and universal public health care. We linked immigration history for the complete population to information on cancer diagnosis from the Cancer Registry of Norway for the period 1990–2012. Age‐standardized (world) overall and site‐specific cancer incidence were estimated for different immigrant groups and compared to incidence among individuals born in Norway. Among 850,008 immigrants, 9,158 men and 10,334 women developed cancer, and among 5,508,429 Norwegian‐born, 263,316 men and 235,020 women developed cancer. While incidence of breast and colorectal cancer were highest among individuals born in Norway and other high‐income countries, other cancer types were higher in immigrants from low‐income countries. Lung cancer incidence was highest in Eastern European men, and men and women from Eastern Europe had high incidence of stomach cancer. Incidence of liver cancer was substantially higher in immigrants from low‐income countries than in individuals born in Norway and other high‐income countries. Our results mirror known cancer challenges across the world. Although cancer incidence overall is lower in immigrants from low‐income countries, certain cancers, such as lung, liver and stomach cancer, represent major challenges in specific immigrant groups.     

Case-control study of risk factors for breast cancer in Nigerian women

This study evaluated the potential risk factors for breast cancer in Nigerian women using a case-control design of 250 women with breast cancer and their age-matched female controls. Both cases and controls were recruited from 4 University Teaching Hospitals in Midwestern and Southeastern Nigeria. Data on the clinical and epidemiological characteristics were collected using interviewer-administered structured questionnaires. The mean age of the cases and controls were 46.1 and 47.1 years, respectively. Fifty-seven percent of the cases were premenopausal while 43% were postmenopausal. The association of risk factors with breast cancer was assessed using conditional logistic regression. Positive family history of breast cancer in first- and second-degree relatives (Odds ratio [OR] = 8.07, 95% confidence interval [CI], 1.003, 64.95, p = 0.04), education of high school level and above (OR = 1.35, 95% CI 1.04, 1.74, p = 0.0205), age at first fullterm pregnancy (FFTP) greater than 20 years (OR = 1.32 95% CI 1.01, 1.71, p = 0.0413) and waist/hip ratio (WHR) (OR = 1.98, 95% CI 1.27, 3.10, p = 0.0026) were associated with increased risk of breast cancer in the final multiple conditional logistic regression model. The findings from this study have shown that sociodemographic characteristics, reproductive variables and anthropometric measures are significant predictors of breast cancer risk in Nigerian women.     

Risk factors for breast cancer in East Asian women relative to women in the West

The incidence of breast cancer in women of East Asian ancestry (Chinese, Japanese and Korean) is lower than in women of European ancestry but is currently rising. This review explores potential reasons for this inter-ethnic difference in incidence by profiling breast cancer risk factors reported for East Asian and Western women. Factors such as endogenous hormone exposure, lifestyle choices, diet and genetic predisposition are associated with breast cancer risk in both East Asian and Western women. However, the relative exposure to these risk factors may vary according to a woman's geographical ancestry and culture. For example, age at menarche and menopause, parity, breast-feeding history, low fat and high soy consumption as well as the prevalence of high risk genetic alleles may vary with a woman's geographical ancestry and/or culture. Differences in exposure to these risk factors in East Asian and Western women are consistent with the inter-ethnic differences in breast cancer incidence observed. Understanding the underlying factors contributing to differences in the profile of breast cancer across populations is important when considering screening and prevention programs for East Asian women resident in the East or the West.     

Risk factors for breast cancer in East Asian women relative to women in the West

The incidence of breast cancer in women of East Asian ancestry (Chinese, Japanese and Korean) is lower than in women of European ancestry but is currently rising. This review explores potential reasons for this inter‐ethnic difference in incidence by profiling breast cancer risk factors reported for East Asian and Western women. Factors such as endogenous hormone exposure, lifestyle choices, diet and genetic predisposition are associated with breast cancer risk in both East Asian and Western women. However, the relative exposure to these risk factors may vary according to a woman's geographical ancestry and culture. For example, age at menarche and menopause, parity, breast‐feeding history, low fat and high soy consumption as well as the prevalence of high risk genetic alleles may vary with a woman's geographical ancestry and/or culture. Differences in exposure to these risk factors in East Asian and Western women are consistent with the inter‐ethnic differences in breast cancer incidence observed. Understanding the underlying factors contributing to differences in the profile of breast cancer across populations is important when considering screening and prevention programs for East Asian women resident in the East or the West.     

Incidence and risk factors associated with bilateral breast cancer in area with early age diagnosis but low incidence of primary breast cancer: analysis of 10-year longitudinal cohort in Taiwan

Summary This study aims to examine the incidence and risk factors of bilateral breast cancer in area with low incidence rate. A total of 120 and 1902 women with bilateral and unilateral breast cancers were enrolled; various factors, including those concerning their medical history and life style, were extracted. Using Kaplan–Meier method, we calculate the cumulative incidence of contralateral breast cancer. The results show as follows. The cumulative incidences of contralateral breast cancer at 1, 3, 5 years after diagnosis of first breast cancer were 1.15, 1.94, and 2.97%, respectively. The statistically significant risk factors included menopause (Hazard Ratio (HR) =1.56, (1.00–2.42)), invasive lobular carcinoma (HR=2.98, (1.35–6.56)), receiving chemotherapy (HR=2.21, (1.43–3.42)) and/or radiotherapy (HR=3.32, (2.19–5.05) and a protective factor was tamoxifen therapy (HR=0.5 (0.34–0.74). Size of the second occurred tumour (2.97 cm) tended to be smaller than the first one (3.58 cm) with borderline statistical significance (p=0.0731). Comparing to the existing data on Western countries, we find a higher risk for developing contralateral breast cancer in Taiwan where a low incidence of first breast cancer rate with early age diagnosis is noted. It suggests that first primary breast tumour with early age of onset and lobular carcinoma are found more likely to develop bilateral breast cancers.Tony Hsiu-Hsi Chen and King-Jen Chang equally contributed to this article.     

Relationship between breast cancer risk factors and mammographic breast density in the Fernald Community Cohort

Background:

We investigated associations of known breast cancer risk factors with breast density, a well-established and very strong predictor of breast cancer risk.

Methods:

This nested case–control study included breast cancer-free women, 265 with high and 860 with low breast density. Women were required to be 40–80 years old and should have a body mass index (BMI) <35 at the time of the index mammogram. Information on covariates was obtained from annual questionnaires.

Results:

In the overall analysis, breast density was inversely associated with BMI at mammogram (P for trend<0.001), and parity (P for trend=0.02) and positively associated with alcohol consumption (ever vs never: odds ratio 2.0, 95% confidence interval 1.4–2.8). Alcohol consumption was positively associated with density, and the association was stronger in women with a family history of breast cancer (P<0.001) and in women with hormone replacement therapy (HRT) history (P<0.001). Parity was inversely associated with density in all subsets, except premenopausal women and women without a family history. The association of parity with density was stronger in women with HRT history (P<0.001).

Conclusion:

The associations of alcohol and parity with breast density appear to be in reverse direction, but stronger in women with a family history of breast cancer and women who ever used HRT.     

Ethnic differences in prostate cancer

Background:

It is recognised that the risk of prostate cancer is higher in black men than in white men worldwide. Recent studies suggest that a number of genetic mutations in black men predispose them to this disease; hence, race as well as environmental factors such as diet and migration are thought to be the determining factors.

Methods:

This review compares data from the United States (US), which suggest that African-American men have a 60% higher risk for developing prostate cancer with poorer prognosis in comparison with their white counterparts, with similar studies carried out in the United Kingdom (UK) and also in African and Caribbean countries.

Conclusions:

Studies from the United States and the United Kingdom came to significantly different conclusions, and this has implications for policy development, awareness raising among black men in each country and clinical practice.     

Ethnic differences in risk perception among women at increased risk for breast cancer

Summary There has been increasing interest in the role of cultural and ethnic factors in breast cancer risk perceptions and screening practices. This study examined ethnic differences in breast cancer risk perception in 112 African American and 224 white women ages 35 and older who had at least one first-degree relative diagnosed with breast cancer. These samples were matched for education and age. Data on breast cancer risk factors, risk perceptions, breast cancer worries, and breast cancer screening practices were collected through structured telephone interviews. The results show that African American women were significantly less likely than white women to report heightened perceptions of personal risk after their relative was diagnosed with breast cancer (61% vs 82%; p<.001). Despite this, African American women had significantly greater concerns about their personal risk of breast cancer and worries about their affected relative. African American women also scored significantly higher than white women on a measure of avoidance of breast cancer-related thoughts and feelings. These psychological variables were associated independently with breast cancer risk perception in multivariate models, taking precedence over demographic and risk factor predictors. Observed ethnic differences in breast cancer risk perceptions and psychological distress may be attributable to the influence of cultural factors particular to people of African descent, such as the importance of interpersonal relationships, spirituality, and time orientation. An Africentric perspective is used to interpret these findings and to provide suggestions for delivering effective breast cancer risk counseling to African American women.     

Behavioral risk factors among Black and White women newly diagnosed with breast cancer

BACKGROUND: To determine the rates of three behavioral risk factors (depression symptoms, smoking, and drinking) among women newly diagnosed with breast cancer and to examine if the rates under investigation differed between Black and White women. METHOD: Subjects were 147 women (47% Black, 53% White) newly diagnosed with breast cancer and participating in an epidemiologic interview study conducted at two metropolitan area cancer centers in the same city. The epidemiologic interview included women's tobacco, alcohol, and drug use history, medical and family history, and depression symptoms. RESULTS: Among all women in the sample, 33% reported clinically significant depression symptoms, 10% currently smoked cigarettes, and 57% currently drank alcohol. Seventy percent of women reported experiencing one or more behavioral risk factors, and White women were more likely than Black women to do so. After controlling for other demographic variables, White women were 50% more likely to report clinical symptoms of depression (odds ratio=1.55, 95% confidence interval=1.03, 2.30) and over two times more likely to report being current drinkers (odds ratio=2.19, 95% confidence interval=1.45, 3.30) than were Black women (p<0.05). CONCLUSIONS: The results suggest that certain behaviors of Black women may be associated with lower levels of self-reported distress. These findings also suggest the need for further research to examine behavioral comorbidity among women with breast cancer, and the roles that race, ethnicity, and culture may play in their expression.     

Association between sleep duration and breast cancer incidence: The multiethnic cohort

Breast cancer is the most common cancer and the second-leading cause of cancer-related death among women. Inconsistent findings for the relationship between melatonin levels, sleep duration and breast cancer have been reported. We investigated the association of sleep duration at cohort entry and its interaction with body mass index (BMI) with risk of developing breast cancer in the large population-based Multiethnic Cohort study. Among the 74,481 at-risk participants, 5,790 breast cancer cases were identified during the study period. Although we detected no significant association between sleep duration and breast cancer incidence, higher risk estimates for short (HR = 1.03; 95% CI: 0.97–1.09) and long sleep (HR = 1.05; 95% CI: 0.95–1.15) compared to normal sleep (7–8 hr) were found. The patterns for models stratified by age, BMI, ethnicity and hormone receptor status were similar but did not indicate significant interaction effects. When examining the combined sleep duration and BMI interaction effect, in comparison to the normal BMI-normal sleep group, risk estimates for underweight, overweight and obesity were similar across categories of sleep duration (≤6, 7–8, and ≥9 hr). The underweight-normal sleep group had lower breast cancer incidence (HR = 0.66, 95% CI: 0.50–0.86), whereas the overweight-short sleep, overweight-normal sleep group and all obese women experienced elevated breast cancer incidence. The respective HRs for short, normal and long sleep among obese women were 1.35 (95% CI: 1.20–1.53), 1.27 (95% CI: 1.15–1.42) and 1.46 (95% CI: 1.21–1.76). Future perspectives need to examine the possibility that sleep quality, variations in circadian rhythm and melatonin are involved in breast cancer etiology.     

Ethnic and geographic differences in mammographic density and their association with breast cancer incidence

The objective of this pooled analysis was to compare differences in dense areas and percent mammographic densities to breast cancer incidence in populations at different breast cancer risk. The data set included 1,327 women aged 40–80: Caucasians from Norway, Arizona, and Hawaii, Japanese from Hawaii and Japan, Latina from Arizona, and Native Hawaiians from Hawaii. One reader performed computer-assisted quantitative density assessment for all mammographic films. Multiple linear regression models evaluated the influence of the covariates on breast density. Spearman correlation coefficients (r _s) estimated the association between breast density and breast cancer incidence for the seven populations. After adjustment for covariates, ethnicity, but not location, was significantly associated with breast density. In the full model, 19% of the variation in the dense areas and 46% in the variation of percent densities were explained by measured risk factors. Native Hawaiians had the largest dense areas and women in Japan the smallest, whereas percent densities were highest among Native Hawaiians and Japanese in Hawaii and lowest among Norwegian women. The mean age-adjusted dense area had the strongest association with breast cancer incidence (r _s = 0.93, P = 0.003); the relation with percent density was considerably weaker (r _s = 0.32, P = 0.48). The correlation between age-adjusted dense area and breast cancer incidence remained strong after selectively removing individual data points. This comparison of mammographic densities suggests that, on a group level, age-adjusted dense areas may reflect breast cancer incidence better than percent densities.     

Evaluating local differences in breast cancer incidence rates: A census-based methodology (United States)

Objectives: We used readily accessible, existing data to assess whether or not geographic variation in breast cancer incidence rates in the San Francisco Bay Area was related to the unequal distribution of known breast cancer risk factors.Methods: Cancer registry and 1990 census block-group data were used to look at the associations between breast cancer incidence and known risk factors (including parity, urban/rural status, and socioeconomic indicators) in 25 California counties. Average annual age-adjusted invasive breast cancer incidence rates were calculated for the period 1988-1992, and adjusted morbidity ratios were computed.Results: While breast cancer incidence in Marin County was 9 percent higher than that of the other 24 counties combined (relative risk=1.09, 95 percent confidence interval=1.01-1.18), this increase appeared to be due to the unequal distribution of known risk factors. Block-groups that had a high level of any risk factor had higher incidence rates, regardless of geographic location. After multivariate adjustment, breast cancer incidence no longer differed between Marin and the other counties (adjusted morbidity ratio=1.02).Conclusions: The results suggest that the unequal distribution of known risk factors was responsible for Marin County's high breast cancer incidence rate.     

Interaction of dense breast patterns with other breast cancer risk factors in a case-control study

The question of interactions between breast density and other breast cancer risk factors is of interest, since it bears upon the use of density as a marker for changes in breast cancer risk. We studied breast parenchymal patterns and 13 other potential risk factors for breast cancer in 172 breast cancer cases and 338 age-matched controls in Singapore. Dense breast patterns were defined as having Tabar parenchymal pattern IV or V. We found significant interactions between dense patterns and ethnic group (P=0.046), and between dense patterns and number of deliveries (P=0.04). Among women with nondense breast patterns, the non-Chinese had lower risk than the Chinese with an odds ratio (OR) of 0.47 (95% CI 0.24, 0.88), whereas in those with dense patterns, the non-Chinese had considerably higher risks (OR=5.34, 95% CI 0.54, 52.51). Alternatively expressed, the increased risk with dense patterns was only observed in the non-Chinese (OR=13.99, 95% CI 1.33, 146.99). Among parous women, the protective effect of three or more deliveries was only observed in those with dense breast patterns (OR=0.21, 95% CI 0.06, 0.70). Suggestive but nonsignificant interactions with dense patterns were observed for ever having delivered, age at first delivery, breast feeding and body mass index. The results are consistent with dense breast patterns as a marker for hormonal modification of breast cancer risk.     

Heterogeneity of breast cancer risk within the South Asian female population in England: a population-based case-control study of first-generation migrants

South Asian women in England have a lower breast cancer risk than their English-native counterparts, but less is known about variations in risk between distinct South Asian ethnic subgroups. We used the data from a population-based case-control study of first-generation South Asian migrants to assess risks by ethnic subgroup. In all, 240 breast cancer cases, identified through cancer registries, were individually matched on age and general practitioner to two controls. Information on the region of origin, religious and linguistic background, and on breast cancer risk factors was obtained from participants. Breast cancer odds varied significantly between the ethnic subgroups (P=0.008), with risk increasing in the following order: Bangladeshi Muslims (odds ratio (OR) 0.33, 95% confidence interval (CI): 0.10, 1.06), Punjabi Hindu (OR 0.59, 95% CI: 0.33, 1.27), Gujarati Hindu (1=reference group), Punjabi Sikh (OR 1.23, 95% CI: 0.72, 2.11) and Pakistani/Indian Muslims (OR 1.76, 95% CI: 1.10, 2.81). The statistically significant raised risk in Pakistani/Indian Muslims increased with adjustment for socioeconomic and reproductive risk factors (OR 2.12, 95% CI: 1.25, 3.58), but was attenuated, and no longer significant, with further adjustment for waist circumference and intake of nonstarch polysaccharides and fat (OR 1.49, 95% CI: 0.85, 2.63). These findings reveal differences in breast cancer risk between South Asian ethnic subgroups, which were not fully explained by reproductive differences, but were partly accounted for by diet and body size.     

Design considerations for identifying breast cancer risk factors in a population‐based study in Africa

Although breast cancer is becoming more prevalent in Africa, few epidemiologic studies have been undertaken and appropriate methodologic approaches remain uncertain. We therefore conducted a population‐based case–control study in Accra and Kumasi, Ghana, enrolling 2,202 women with lesions suspicious for breast cancer and 2,161 population controls. Biopsy tissue for cases prior to neoadjuvant therapy (if given), blood, saliva and fecal samples were sought for study subjects. Response rates, risk factor prevalences and odds ratios for established breast cancer risk factors were calculated. A total of 54.5% of the recruited cases were diagnosed with malignancies, 36.0% with benign conditions and 9.5% with indeterminate diagnoses. Response rates to interviews were 99.2% in cases and 91.9% in controls, with the vast majority of interviewed subjects providing saliva (97.9% in cases vs. 98.8% in controls) and blood (91.8% vs. 82.5%) samples; lower proportions (58.1% vs. 46.1%) provided fecal samples. While risk factor prevalences were unique as compared to women in other countries (e.g., less education, higher parity), cancer risk factors resembled patterns identified elsewhere (elevated risks associated with higher levels of education, familial histories of breast cancer, low parity and larger body sizes). Subjects with benign conditions were younger and exhibited higher socioeconomic profiles (e.g., higher education and lower parity) than those with malignancies, suggesting selective referral influences. While further defining breast cancer risk factors in Africa, this study showed that successful population‐based interdisciplinary studies of cancer in Africa are possible but require close attention to diagnostic referral biases and standardized and documented approaches for high‐quality data collection, including biospecimens.     

Breast cancer risk factors and a novel measure of volumetric breast density: cross-sectional study

We conducted a cross-sectional study nested within a prospective cohort of breast cancer risk factors and two novel measures of breast density volume among 590 women who had attended Glasgow University (1948-1968), replied to a postal questionnaire (2001) and attended breast screening in Scotland (1989-2002). Volumetric breast density was estimated using a fully automated computer programme applied to digitised film-screen mammograms, from medio-lateral oblique mammograms at the first-screening visit. This measured the proportion of the breast volume composed of dense (non-fatty) tissue (Standard Mammogram Form (SMF)%) and the absolute volume of this tissue (SMF volume, cm3). Median age at first screening was 54.1 years (range: 40.0-71.5), median SMF volume 70.25 cm3 (interquartile range: 51.0-103.0) and mean SMF% 26.3%, s.d.=8.0% (range: 12.7-58.8%). Age-adjusted logistic regression models showed a positive relationship between age at last menstrual period and SMF%, odds ratio (OR) per year later: 1.05 (95% confidence interval: 1.01-1.08, P=0.004). Number of pregnancies was inversely related to SMF volume, OR per extra pregnancy: 0.78 (0.70-0.86, P<0.001). There was a suggestion of a quadratic relationship between birthweight and SMF%, with lowest risks in women born under 2.5 and over 4 kg. Body mass index (BMI) at university (median age 19) and in 2001 (median age 62) were positively related to SMF volume, OR per extra kg m(-2) 1.21 (1.15-1.28) and 1.17 (1.09-1.26), respectively, and inversely related to SMF%, OR per extra kg m(-2) 0.83 (0.79-0.88) and 0.82 (0.76-0.88), respectively, P<0.001. Standard Mammogram Form% and absolute SMF volume are related to several, but not all, breast cancer risk factors. In particular, the positive relationship between BMI and SMF volume suggests that volume of dense breast tissue will be a useful marker in breast cancer studies.     

应用分类树模型研究乳腺癌危险因素

目的应用分类树模型筛选乳腺癌的危险因素,并预测其发病风险,为乳腺癌的干预提供科学依据。方法用问卷调查及实验室检测等方式采集2010年7月至2012年6月就诊于黑龙江省牡丹江市第一、二人民医院及牡丹江医学院附属红旗医院的1023名女性的相关数据,利用分类树模型分析乳腺癌的影响因素,采取ROC曲线对模型进行评价。结果乳腺癌的危险因素为乳腺癌家族史、长期精神压抑、流产次数（≥3次）、初潮年龄（≤12岁）、平均行经时间（〉7d）、足月妊娠、乳腺良性疾病史、腰臀比（30．8）、职业和体质指数（325）,食用豆类食品（1周不少于2次）、体育锻炼和哺乳情况（母乳喂养）为乳腺癌发生的保护因素（P〈0．050）。结论利用分类回归树模型可以快速、有效的从众多数据中挖掘出影响乳腺癌发病的主要因素并预测人群乳腺癌的发病风险,在流行病学研究中具有较高的应用价值。     

Invasive breast cancer incidence trends by detailed race/ethnicity and age

Racial/ethnic disparities in breast cancer incidence may contain important evidence for understanding and control of the disease. Monitoring the incidence trends of breast cancer by race/ethnicity allows identification of high risk groups and development of targeted prevention programs. Using population-based cancer registry data from the Los Angeles Cancer Surveillance Program, we examined the invasive female breast cancer incidence trends among the diverse racial/ethnic populations in Los Angeles County, California, from 1972 to 2007. Age-adjusted incidence rates (AAIRs) and age-specific incidence rates (ASIRs) were calculated and examined respectively for non-Hispanic (NH) white, black, Hispanic, Chinese, Filipina, Japanese and Korean women by calendar year and time period. Rising trends of AAIRs were found in all racial/ethnic groups during the 1980s and 1990s. The breast cancer risk increased more substantially in Japanese and Filipinas than in Chinese and Koreans. During 2000-2007, the trends of AAIRs declined significantly among NH white women and slightly in blacks, remained unchanged for Hispanics and continued to rise significantly among all Asian subgroups. The patterns of ASIRs by race/ethnicity changed dramatically over time. By 2000-2007, younger Hispanic women had the lowest breast cancer risk, replacing the Chinese and Koreans who formerly had the lowest risk. Rapidly increasing breast cancer incidence trends among Asian-Americans underline the importance of behavioral and lifestyle changes as a result of acculturation on the development of the disease. The unique trends of breast cancer incidence by race/ethnicity suggest the need for targeted breast cancer control programs for different racial/ethnic populations.     

Global incidence,risk factors and trends of vulvar cancer: A country-based analysis of cancer registries

Vulvar cancer is an uncommon malignancy. Vulvar cancer alarmed the public health problem in terms of the cost of diagnostic and medical treatments and psychical health of females. Our study aims to provide a thorough analysis of the global disease burden, related risk factors and temporal incidence trends of vulvar cancer in population subgroups. Data from Global Cancer Observatory and the Cancer Incidence in Five Continents Plus were used for the vulvar cancer incidence. Age-standardized rates (ASR) were used to depict the incidence of vulvar cancer. The 10-year trend of incidence was assessed using joinpoint regression with average annual percentage change and 95% confidence intervals in various age groups, while its correlations with risk factors were investigated using linear regression. Higher ASR were found in Western Europe (2.4), Northern America (1.9), Northern Europe (1.9), Australia and New Zealand (1.8) and Eastern Africa (1.4). The associated risk factors of higher vulvar cancer incidence were gross domestic product per capita, Human Development Index, higher prevalence of smoking, alcohol drinking, unsafe sex and human immunodeficiency virus infection. The overall trend of vulvar cancer incidence was increasing. An increasing trend was found in older females while a mixed trend was observed in younger females. The disease burden of vulvar cancer follows a bimodal pattern according to its two histologic pathways, affecting women in both developed and developing regions. Smoking cessation, sex education and human papillomavirus vaccination programs should be promoted among the general population. Subsequent studies can be done to explore the reasons behind the increasing trend of vulvar cancer.