When Dollars Meet Diagnosis

When Dollars Meet Diagnosis: Exploring the Relationship Between Income Levels and Cancer Incidence Across U.S. States

T.J. Greer, PhD

Abstract

This study investigates the correlation between state income levels and cancer cases across various states in the United States. The income data is from the World Population Review, and the cancer rate data came from the American Cancer Society. A correlation analysis was conducted to determine the relationship between these two variables. The results indicate a weak positive correlation coefficient of approximately 0.193 between income and cancer cases. This suggests that higher income levels may be associated with a slight increase in the number of cancer cases, although the relationship is not strong enough to imply causation. The findings highlight the complexity of health outcomes and socioeconomic factors, warranting further investigation into the underlying causes and contributing factors.

Introduction

Cancer remains one of the most pressing public health challenges in the United States, with its incidence and outcomes heavily influenced by socioeconomic factors, particularly income. A growing body of research has explored the link between income levels and cancer prevalence, revealing complex and sometimes counterintuitive patterns. Recent studies have found that higher income levels are often associated with increased cancer incidence, potentially due to improved access to screening and diagnostic services that lead to higher detection rates. For instance, a study demonstrated that wealthier individuals had higher exposure-adjusted risks for thyroid cancer, suggesting that both income and environmental factors contribute to detection disparities . Similarly, researchers identified a strong positive correlation between national socioeconomic indices like the Human Development Index and higher thyroid cancer rates, supporting the idea that wealthier populations may be more likely to detect cancer early due to better healthcare access .

Other studies reinforce this trend. An analysis observed that breast and prostate cancers, which often require regular screenings, were more commonly diagnosed in higher-income groups. This pattern was echoed in research where investigators found that both individual and neighborhood-level income were positively associated with breast cancer incidence. The rationale is that wealthier women are more likely to undergo routine mammography, resulting in higher documented incidence rates. In contrast, cancers linked to poorer prognoses and environmental exposures, such as cervical and liver cancers, were found to be more prevalent in lower-income populations according to research published in Frontiers in Oncology.

Regional disparities also offer insight into this association. Studies conducted in Germany and England observed that lower socioeconomic status at the neighborhood or regional level correlated with higher mortality rates but not always higher incidence rates, further reinforcing the distinction between detection and survival. U.S.-based data highlighted similar trends, where higher income often predicted a greater likelihood of cancer diagnosis, but not necessarily worse outcomes, due to superior treatment access. Finally, recent work using population-level data confirmed that the positive association between income and cancer diagnosis is largely explained by greater participation in screening programs, rather than an actual higher disease burden.

These findings collectively reveal a nuanced picture in which higher income is often linked with higher reported cancer incidence—largely due to improved healthcare access and early detection—while lower income is frequently associated with later-stage diagnoses and worse outcomes. Understanding this dynamic is essential for crafting equitable health policies and tailoring cancer prevention strategies to meet the needs of diverse economic populations. This paper adds to that growing literature by analyzing state-level income data and corresponding cancer case rates to investigate whether this income-incidence relationship holds across U.S. states.

Methods

This study employed a correlational research design to explore the relationship between state-level income and cancer incidence across the United States. Data on median annual income per state (in USD) were compiled from publicly available government economic statistics, while cancer case counts were obtained from state-level public health and cancer registry reports. Each state's data point represented its median income alongside its reported number of cancer cases for the most recent annual period.

Income data were standardized to thousands of dollars to ensure comparability across states. Correlation analysis was performed using the Pearson correlation coefficient to assess the linear relationship between the two variables—state income and cancer case count. This statistical method was chosen for its effectiveness in measuring the strength and direction of linear relationships between continuous variables.

The analysis was conducted using spreadsheet software and statistical computing tools to verify consistency in results. The correlation coefficient value was interpreted based on conventional thresholds, where values between 0.1 and 0.3 indicate a weak positive correlation. Limitations of the study include the lack of control for confounding variables such as population size, age distribution, healthcare access, and environmental factors, which may influence cancer incidence rates independently of income.

Discussion

The correlation analysis conducted in this study reveals a weak positive relationship between state income levels and cancer incidence rates. While the coefficient suggests some association, the strength of the correlation is insufficient to indicate a direct or causal link. These findings align with prior research indicating that wealthier populations often report higher cancer incidence, particularly for cancers such as thyroid, breast, and prostate (Ahn et al., 2022; Singh et al., 2017). However, this trend is widely understood to reflect differences in detection rates rather than actual disparities in disease prevalence (Clegg et al., 2009).

Increased access to health insurance, routine medical visits, and preventive screenings is more common among individuals with higher income levels, which likely contributes to the increased detection of cancer cases in these populations (Freeman & Reuben, 2021). Conversely, lower-income individuals often face barriers including lack of insurance, geographic distance from medical facilities, and fewer opportunities for early screening (DeSantis et al., 2016). These disparities in access to care can distort incidence statistics, making cancer appear more prevalent in wealthier populations when, in reality, it may be simply more frequently diagnosed (Ward et al., 2004).

Moreover, the complexity of cancer risk factors introduces multiple lurking variables that confound attempts to isolate income as a singular explanatory factor. Environmental exposures, occupational hazards, genetic predispositions, and lifestyle behaviors—such as smoking and dietary habits—are not evenly distributed across income brackets and may vary by region, education level, and race or ethnicity (Singh et al., 2011). For instance, even within higher-income populations, urban environments may expose residents to more pollutants that elevate cancer risks, while cultural health beliefs and health literacy also influence detection (Krieger et al., 2003). Thus, income operates more as a proxy for other factors—chief among them being access to healthcare and the ability to act on health information—than as an independent determinant of cancer risk (Siegel et al., 2024).

Conclusion

Overall, although this study identified a weak positive correlation between income and cancer rates across U.S. states, the relationship is likely due more to diagnostic disparities than to actual differences in cancer prevalence. Higher-income individuals are more likely to have health insurance, undergo regular screenings, and receive early diagnoses—factors that inflate incidence figures for this group (Freeman & Reuben, 2021; DeSantis et al., 2016). At the same time, lower-income populations face significant access barriers that may lead to underdiagnosis or diagnosis at later stages.

Given the many lurking variables involved—including environmental exposures, healthcare infrastructure, education, and occupational risks—drawing a direct causal link between income and cancer rates is overly simplistic. Instead, income should be seen as a marker for broader systemic advantages or disadvantages in health access and prevention. Future research should control for these confounding variables and employ multivariate models to clarify the role income plays within this complex framework. Nevertheless, the findings emphasize the urgent need to improve healthcare access and equity for economically disadvantaged groups—not only to improve outcomes but also to ensure the accuracy and fairness of cancer surveillance across populations (Siegel et al., 2024; Singh et al., 2017).

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