Disparities in Breast Cancer Screening, Diagnosis, and Outcomes Among Vietnamese American Women: A Systematic Review.

1
Introduction
Breast cancer remains the most frequently diagnosed cancer and a leading cause of cancer‐related mortality among women globally [1]. Despite significant advances in early detection and treatment that have improved survival rates, inequities in screening, diagnosis, and care continue to disproportionately affect ethnic minority populations [2, 3]. Vietnamese women, in particular, represent a unique group that faces distinct sociocultural, linguistic, and systemic barriers in breast cancer prevention and treatment [4]. Within the United States, studies have shown that Vietnamese women have lower rates of breast cancer screening, higher rates of late‐stage diagnoses, and limited access to culturally tailored healthcare interventions [5, 6, 7]. These challenges contribute to disparities in outcomes and highlight the urgent need for targeted solutions. In addition to sociocultural and systemic factors, biological differences in breast cancer characteristics among Vietnamese women have begun to emerge in the literature. Molecular and genetic studies reveal distinct tumor subtypes and biomarker expression profiles that may influence prognosis and therapeutic response in this population [8]. These findings underscore the importance of integrating biological insights with social and structural determinants of health to develop a more comprehensive understanding of the breast cancer burden in Vietnamese women.
This systematic review synthesizes evidence published between 2000 and 2024 to examine the multifaceted challenges faced by Vietnamese women in the context of breast cancer screening, diagnosis, treatment, and outcomes. Drawing from studies conducted across diverse contexts, this review explores breast cancer screening behaviors, disparities in access to care, biological and molecular characteristics of breast cancer, and the effectiveness of interventions tailored to this population. By analyzing these intersecting domains, this review aims to illuminate patterns and gaps in the current evidence base and provide actionable recommendations for addressing breast cancer disparities in Vietnamese women through culturally and contextually informed approaches.

2
Materials and Methods
This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) guidelines to ensure a transparent and rigorous process (Figure 1). The protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO) (Registration ID: CRD42024654266) to predefine objectives, inclusion criteria, and methodologies, minimizing potential biases. A comprehensive literature search was conducted across PubMed, Embase, and Scopus databases to identify relevant studies published between January 1, 2000 and December 31, 2024. The search strategy utilized keywords and Medical Subject Headings (MeSH) terms related to “Vietnamese,” “breast cancer,” “screening,” “outcomes,” “interventions,” and “disparities.”
Inclusion criteria encompassed original studies that examined breast cancer screening, outcomes, molecular/genetic features, or disparities among Vietnamese populations. Only studies providing primary data, published in English, and offering separate findings for Vietnamese participants were included. Reviews, commentaries, editorials, and abstracts without accessible full text were excluded. Two reviewers independently screened titles and abstracts, followed by full‐text evaluation for eligibility, with disagreements resolved through discussion or consultation with a third reviewer. Data extraction was performed using a standardized form to capture key variables, including author(s), publication year, study design, sample size, Vietnamese participant demographics, breast cancer metrics, and statistical findings. Two reviewers extracted data independently to ensure accuracy and consistency, and discrepancies were resolved through consensus. Risk of bias in observational studies was assessed using the Newcastle‐Ottawa Scale (NOS), while the Cochrane Risk of Bias Tool was used for randomized controlled trials (Table 1).
Given the heterogeneity in study designs, metrics, and outcomes, a narrative synthesis was conducted, organizing results into thematic categories: breast cancer screening behavior and barriers, breast cancer outcomes, interventions and education, molecular/genetic features, and broader disparities in access and care. Quantitative meta‐analysis was considered for outcomes with comparable measures, such as odds ratios for mammography screening or late‐stage diagnosis, but methodological and population variability precluded pooling of data. Instead, findings were synthesized qualitatively to identify patterns, gaps, and implications. This review exclusively included studies from primary databases and avoided reviews or secondary analyses to focus solely on original research. As all data were publicly available, ethical approval was not required.

3
Results
This systematic review includes 41 studies and 39,324 Vietnamese participants with a mean age of 48.15 years (SD = 7.48). The following themes were included in the narrative synthesis of these studies: breast cancer screening behavior and barriers, breast cancer outcomes, interventions and education, molecular/genetic features, and disparities to access and care (Table 2). In this population, social integration refers to the degree of connectedness within family and community networks, while instrumental support encompasses tangible assistance such as transportation or appointment scheduling. Acculturation describes the extent to which individuals adopt U.S. cultural norms, including language proficiency and familiarity with the healthcare system.
3.1
Breast Cancer Screening Behavior and Barriers
Breast cancer screening behavior among Vietnamese women is shaped by a complex interplay of social, cultural, and systemic factors, as evidenced by multiple studies. Social networks emerged as critical influencers in Le (2011), where increased social integration significantly enhanced clinical breast exam (CBE) uptake (OR = 1.20, 95% CI: 1.07–1.33) and instrumental support predicted mammography use (OR = 1.05, 95% CI: 1.02–1.08) [9]. Similarly, Shaw et al. (2012) found social connections influence cancer screening, with family and friends encouraging screening through shared positive experiences, while misinformation, such as beliefs that screenings are unnecessary without symptoms, discouraged participation [10]. Furthermore, several studies identified systemic barriers to screening. Nguyen et al. (2018) found that limited English proficiency, lack of insurance, and cultural beliefs significantly deterred Vietnamese American women from participating in routine screening programs [11]. Similarly, McGarvey et al. (2003) reported that cost, lack of knowledge, and cultural stigma were perceived as significant barriers, paralleling findings in Sadler et al. (2001), where Vietnamese women displayed low levels of breast cancer knowledge, leading to low adherence to mammography guidelines [12, 13]. Shon et al. (2019), Ho et al. (2005), Ma et al. (2009) and Ma et al. (2012) corroborated these findings [14, 15, 16, 17].
Cultural factors, such as collectivism and acculturation, play a crucial role in shaping cancer screening behaviors. Collectivism, which emphasizes the importance of family and community over individual concerns, fosters greater social support and encouragement for preventive health behaviors. In Vietnamese communities, this often manifests as family members urging women to undergo screening or accompanying them to appointments [18]. Acculturation, the process of adapting to the norms and practices of a new culture, similarly influences screening attitudes. Higher levels of acculturation are associated with increased familiarity with the U.S. healthcare system, improved English proficiency, and greater self‐efficacy in seeking preventive care, ultimately contributing to higher screening participation [18]. Nguyen AB and Belgrave (2014) similarly reported that ethnic identity moderated cancer screening behaviors, with culturally tailored community‐based participatory research (CBPR) interventions effectively improving screening knowledge and participation [19]. Education and outreach programs demonstrated mixed success in improving screening rates. Nguyen et al. (2001) noted that media‐led and neighborhood‐based interventions had limited effects overall but significantly improved screening behaviors when participants were exposed to multiple intervention elements [20]. In contrast, Nguyen‐Truong et al. (2018) documented that Vietnamese‐American women's screening rates (64%) in their study fell below the national average, with fear, cultural beliefs, and lack of knowledge being primary barriers [21].
Vietnamese women face significant barriers related to language and nativity. Ryu et al. (2013) observed that higher screening rates often reflect participation among more acculturated individuals, while less acculturated women experience difficulty navigating healthcare systems due to limited English proficiency, unfamiliarity with preventive care practices, and mistrust stemming from cultural differences [22]. Specifically, Vietnamese women with limited English proficiency were 43% less likely to undergo mammography screening compared to their English‐proficient counterparts (OR = 0.57, 95% CI: 0.42–0.78) [11]. Kandula et al. (2006) similarly reported that Vietnamese women with less than 10 years of U.S. residency were significantly less likely to engage in mammography screening compared to those with longer residency durations (72.7% vs. 82.5%; p < 0.01) [23]. These findings suggest that the reported screening success may mask underlying disparities, particularly among recent immigrants and those with lower acculturation levels.
Lastly, disparities in mammography utilization were underscored by multiple studies. Gomez et al. (2007) reported that Vietnamese women who had not undergone prior Pap smears were less likely to have mammograms, while single marital status further increased the risk of non‐adherence [24]. Similarly, Ly I. Nguyen et al. (2000) found that Vietnamese women in Hawaii exhibited lower mammography rates (26%) compared to other ethnic groups, with the CDC reporting the U.S. national average of mammography at 81%, emphasizing the need for interventions tailored to address specific cultural and systemic challenges [25]. Figure 2 illustrates the variability in screening rates across studies reporting mammography utilization among Vietnamese women. Percentages ranged from 26% in Nguyen et al. (2000) to 83% in Ryu et al. (2013), with higher rates generally observed in more acculturated subgroups. Late‐stage breast cancer diagnosis is also a persistent issue. According to Bock et al. (2023), 33% of breast cancer diagnoses among Vietnamese individuals occurred at a late stage, which compares to 30% in non‐Hispanic white (NHW) women, indicating challenges in early detection and intervention [26].

3.2
Breast Cancer Outcomes
The outcomes of breast cancer among Vietnamese women reveal substantial disparities in survival rates, tumor characteristics, and treatment patterns when compared to other ethnic groups. Survival outcomes for Vietnamese women are significantly influenced by nativity and socioeconomic factors. Gomez et al. (2010) highlighted that foreign‐born Vietnamese women exhibited nearly four times higher mortality than U.S.‐born Vietnamese women (HR = 3.9, 95% CI: 1.4–10.6) [27]. Similarly, Li et al. (2003) reported poorer survival rates for Vietnamese women compared to NHW women, despite a lower likelihood of receiving inappropriate therapy [28]. Conversely, Medina et al. (2021) observed that Vietnamese women had lower breast cancer mortality rates compared to NHW women (12.4 per 100,000 vs. 20.2 per 100,000), potentially reflecting the success of screening and early detection efforts in some subpopulations [29].
Disease‐specific survival (DSS) data further underscore these disparities. Yi et al. (2012) found a 5‐year DSS rate of 89.6% for Vietnamese women, noting that younger age at diagnosis (median: 51 years) and tumor stage were significant predictors of survival [30]. This compares to a 5‐year DSS for U.S. breast cancer overall of 92%. This aligns with findings by Lin et al. (2002), who reported that Vietnamese women were diagnosed at a younger age (mean: 51 years) compared to other racial groups and exhibited higher mastectomy rates (61.1%) for in situ or localized tumors in comparison to the national U.S. rates of 35–40% [31]. Moreover, treatment disparities are evident, particularly in surgical interventions. Nguyen et al. (2009) and Lin et al. (2002) both highlighted significantly higher mastectomy rates among Vietnamese women, which were often influenced by nativity, tumor stage, and cultural factors [31, 32]. Patel et al. (2023) revealed that Vietnamese women had a 17% higher odds of delayed surgery (OR = 1.17, 95% CI: 1.06–1.29), emphasizing disparities in timely access to care [33].

3.3
Interventions & Education
Efforts to improve breast cancer awareness and screening behaviors among Vietnamese women have focused on culturally tailored interventions and education programs, with significant success in enhancing knowledge, attitudes, and adherence to screening recommendations. For example, Nguyen‐Truong et al. (2017) demonstrated the feasibility and effectiveness of a multicomponent breast health education intervention targeting Vietnamese American immigrant women aged ≥ 50 years [34]. This pilot study reported a significant improvement in breast cancer knowledge (mean pre‐test score: 0.33 ± 1.37 vs. post‐test: 0.63 ± 0.53, t(39) = –14.72, p < 0.001) and perceived susceptibility to breast cancer (mean pre‐test: 2.87 ± 0.83 vs. post‐test: 3.32 ± 0.70, t(39) = –2.69, p < 0.05). Moreover, the intervention successfully increased mammogram completion rates, with 30 out of 39 participants (77%) undergoing mammography within 12 weeks of the intervention from a baseline of 0%, highlighting the importance of culturally relevant, comprehensive education programs in addressing disparities in screening behaviors [34].
Community‐based participatory research (CBPR) has been instrumental in addressing cultural barriers to screening. Nguyen and Belgrave (2014) evaluated a CBPR intervention that emphasized ethnic identity and collectivism to enhance breast cancer screening knowledge and behavior [19]. The intervention significantly improved clinical breast exam rates (Nagelkerke R² = 0.36, p = 0.002) and highlighted how cultural values influence screening attitudes and participation [19]. Similarly, Nguyen, Belgrave, and Sholley (2011) conducted a three‐phase CBPR study that resulted in marked improvements in cancer knowledge and self‐efficacy among participants [35]. The intervention's emphasis on culturally tailored outreach was key to its success.
Thai et al. (2020) assessed the impact of a patient navigator program designed for Vietnamese‐American women with abnormal mammograms [36]. The program achieved 100% adherence to follow‐up appointments within 3 months of receiving abnormal results, underscoring the critical role of navigators in addressing logistical and emotional barriers. However, mixed psychosocial outcomes, such as increased anxiety in some participants, pointed to the need for further refinement of intervention strategies.
Apartment‐based education programs have also proven effective for underserved Vietnamese women. Yi and Luong (2005) conducted a randomized controlled trial evaluating a program aimed at increasing breast cancer knowledge and breast self‐exam (BSE) practices among low‐income Vietnamese women [37]. The intervention group showed significant improvements in knowledge (mean score increase: +4.2, p < 0.001) and a 50.8% increase in BSE practices (p < 0.001). The program's localized and culturally sensitive approach made it particularly successful in reaching marginalized populations.
Finally, Nguyen and Clark (2014) examined the interplay between cultural barriers, acculturation, and tailored interventions in cancer screening behaviors [18]. The study found that addressing collectivism and cultural norms, while leveraging community resources, significantly influenced participants’ screening self‐efficacy and attitudes. These findings emphasize the need for interventions that go beyond general health education to address sociocultural dynamics specific to Vietnamese women.

3.4
Disparities in Access & Care
Several studies highlight disparities in access to breast cancer screening, diagnosis, and care among Vietnamese women, emphasizing structural and cultural barriers that hinder equitable healthcare outcomes. Gomez et al. (2007) examined disparities in mammography use among Asian women in California, with a specific focus on Vietnamese women [38]. The study found that Vietnamese women who had not undergone a Pap smear were significantly less likely to have a mammogram in the past 2 years (72% non‐adherence). Single marital status and lack of access to care further exacerbated disparities in mammography adherence, suggesting that broader issues in women's healthcare access cascade across multiple cancer screening behaviors. Trinh et al. (2015) assessed cancer‐specific mortality across stages and treatment receipt among Asian American subgroups [39]. Disparities in the receipt of definitive treatment, including curative interventions like surgery, radiation, or systemic therapy, were evident across various breast cancer stages. This gap in care points to systemic barriers, such as healthcare infrastructure and socioeconomic constraints, that impact the timely diagnosis and treatment of cancer in Vietnamese populations.

3.5
Molecular/Genetic Features
Studies exploring the molecular and genetic features of breast cancer in Vietnamese populations have provided valuable insights into tumor biology and subtype‐specific characteristics, highlighting unique patterns that may influence prognosis and treatment strategies. Radhakrishnan et al. (2015) examined the role of IGF‐II expression in triple‐negative breast cancer (TNBC) among Vietnamese patients [40]. The study found that all paired normal tissue samples exhibited biallelic IGF‐II expression, while tumors with biallelic IGF‐II gene expression showed elevated levels of proIGF‐II and Survivin proteins. These findings linked the loss of imprinting (LOI) and biallelic IGF‐II expression with more aggressive TNBC phenotypes, underscoring the potential prognostic value of IGF‐II in this population. In addition, molecular characteristics of tumors vary among Vietnamese women. Telli et al. (2011) documented a 29% frequency of HER2‐positive breast cancer among Vietnamese women, significantly higher than NHW women (19%; OR = 1.3, 95% CI: 1.1–1.6) [41]. The study also identified a moderate frequency of triple‐negative breast cancer (TNBC) at 14%. Williams et al. (2009) investigated TNBC in Vietnamese women compared to U.S. counterparts using tissue microarray analysis [42]. Vietnamese TNBC cases were characterized by smaller tumor sizes (mean: 3.2 cm vs. 4.7 cm) and lower rates of grade III tumors (62% vs. 84%). Molecular marker expression also differed, with underexpression of EGFR and P‐cadherin and overexpression of CK8 in Vietnamese women. These differences suggest a less aggressive tumor phenotype in Vietnamese TNBC cases and point to distinct biological pathways underlying tumor development in this group.

4
Discussion
This systematic review is the first to comprehensively synthesize evidence on the unique disparities in breast cancer screening, diagnosis, treatment, and outcomes among Vietnamese‐American women, highlighting the combined influence of sociocultural, systemic, and molecular factors on care access and health outcomes.
The breast cancer screening behaviors of Vietnamese women are shaped by a complex interplay of cultural, systemic, and structural factors. Social networks, for instance, serve as both facilitators and barriers to screening uptake, depending on the nature and influence of these relationships. While social support has been shown to positively impact engagement with clinical breast exams (CBEs) and mammography, misinformation within these networks can perpetuate fear and misconceptions about cancer screening [9, 10]. This highlights the need for community‐driven educational campaigns that leverage trusted social networks to promote accurate information and encourage screening participation. Additionally, language barriers, lack of insurance, and cultural stigma remain persistent obstacles, particularly for recently immigrated populations [11, 12]. Interventions must move beyond simple language translation to include culturally congruent health messaging that resonates with the values and beliefs of Vietnamese women. Health systems should prioritize collaborations with community leaders to build trust and improve the effectiveness of outreach programs.
Additionally, disparities in breast cancer outcomes underscore the intersection of biological, structural, and socioeconomic factors. Late‐stage diagnosis remains a persistent issue, with 32.9% of Vietnamese breast cancer cases identified at an advanced stage [26]. Mortality rates are also disproportionately higher among foreign‐born Vietnamese women compared to their U.S.‐born counterparts, highlighting the influence of immigration‐related factors, including healthcare access, cultural perceptions of cancer, and health literacy [27]. Programs that extend beyond hospital‐based care to community settings may offer more accessible pathways for early detection and treatment adherence, especially for recently immigrated individuals.
Intervention studies demonstrate the potential effectiveness of culturally tailored programs to improve screening rates, though the heterogeneity in outcomes suggests that these programs require ongoing evaluation and adaptation. CBPR interventions have yielded promising results by integrating cultural norms like collectivism and familial decision‐making into educational materials [19, 35]. However, these programs are resource‐intensive and require context‐specific modifications to maintain engagement across diverse Vietnamese communities. Patient navigation programs have also demonstrated substantial success in reducing follow‐up loss after abnormal mammograms, but scaling these interventions requires sufficient resources and staffing [36]. Expanding the availability of navigators, particularly those with shared linguistic and cultural backgrounds, may help mitigate healthcare system navigation barriers.
Access to care remains a fundamental challenge for Vietnamese women, with linguistic, socioeconomic, and geographic barriers contributing to delayed diagnoses and suboptimal treatment outcomes. Language barriers have consistently been associated with lower screening rates and increased mortality risk [11, 30]. Geographic disparities are equally significant, with only 10% of cancer care facilities in Southern California offering Vietnamese‐language services [43, 44]. Additionally, Vietnamese women with lower acculturation levels are less likely to participate in screening and may delay follow‐up care after abnormal findings [24, 45]. Expanding access to culturally and linguistically tailored services, particularly in areas with large Vietnamese communities, should be a priority for policymakers [46, 47, 48]. Furthermore, structural interventions, such as insurance expansions and partnerships with community organizations, could help bridge gaps in care access [49]. Lastly, Telli et al. (2011) and Williams et al. (2009) found potential ethnic‐specific variations in tumor biology, which may have implications for treatment strategies [41, 42]. However, the current body of molecular research remains limited in scope, underscoring the need for further investigation into potential pharmacogenomic differences that could guide personalized care approaches.
4.1
Limitations
This systematic review has limitations. First, there were a limited number of studies focusing specifically on Vietnamese women and breast cancer. Despite a comprehensive search across multiple databases, relatively few studies provided disaggregated data for this population, particularly in areas such as molecular characteristics, treatment outcomes, and the effectiveness of interventions. Second, the heterogeneity in study designs, sample sizes, and outcome definitions limited the ability to perform a meta‐analysis. Variability in data sources, including self‐reported screening behaviors and registry data, introduces potential recall, reporting, and selection biases. Geographically, most studies focused on Vietnamese women in the United States, particularly in California and Texas, limiting generalizability to other regions. Few studies disaggregated findings by nativity or immigration status, despite their known influence on screening behaviors and outcomes. Future research should use standardized measures, include diverse populations, and incorporate longitudinal analyses to better understand these disparities.

5
Conclusion
Vietnamese women face unique challenges in breast cancer prevention and care, shaped by sociocultural, systemic, and biological factors. Disparities in screening utilization, late‐stage diagnoses, and access to timely care persist, driven by barriers such as limited English proficiency, cultural beliefs, and structural inequities in healthcare systems. Distinct molecular and genetic characteristics of breast cancer in this population further highlight the need for tailored diagnostic and therapeutic strategies. While community‐based interventions, such as patient navigation and culturally sensitive education programs, have demonstrated promise in improving knowledge and adherence to screening, these efforts must be expanded and integrated into broader healthcare policies. Addressing these challenges requires a comprehensive approach that combines culturally tailored education, improved access to linguistically competent care, and ongoing research into population‐specific tumor biology. By bridging these gaps, healthcare systems can promote equitable breast cancer outcomes for Vietnamese women and other underserved populations.

Conflicts of Interest
The authors declare no conflicts of interest.

Synopsis
This systematic review examines disparities in breast cancer screening, diagnosis, and outcomes among Vietnamese American women. Analyzing 41 studies with 39,324 participants, the review identifies sociocultural, linguistic, and systemic barriers that contribute to lower screening rates, later‐stage diagnoses, and distinct molecular tumor characteristics. Findings underscore the need for culturally tailored interventions, improved healthcare access, and further research into population‐specific tumor biology.