Impact of Socioeconomic Factors and Health-Care Access on Cancer Screening and Treatment
Socioeconomic status has long been thought to play an important role in health-care disparities across a wide variety of diseases. It is closely related to health-care access and acculturation in recent immigrant minority groups. Much of the research in this area related to cancer has focused on differences between African-Americans and non-Hispanic whites. Less data is available for other minority populations including Hispanics and Native Americans.
Breast Cancer in African-Americans
The curious difference between lower breast cancer incidence and higher mortality for African-Americans offers fertile ground for research. Several studies have demonstrated an attenuation of risk when controlled for socioeconomic status. Lannin and colleagues demonstrated a drop from a 3.0-fold (95% confidence interval [CI] = 1.9-4.7-fold) risk of advanced-stage breast cancer in African-Americans compared to white women down to 1.8-fold (95% CI = 1.1-3.2-fold) when adjusted for socioeconomic status. For Hispanic women, Miller et al found that a 50% increase in risk of advanced-stage breast cancer compared to non-Hispanic white women was reduced to a 10% elevation when adjusted for socioeconomic status.
One particularly creative study used the Peters-Belson (PB) approach to evaluate discrepancies in cancer screening rates. The PB approach is a complex regression analysis borrowed from social scientists who use it for wage discrimination studies. The model uses covariates that are thought to explain discrepancies between groups and then evaluates how much of the actual difference is explained by the identified variants. In the analysis of cancer screening, the covariates were age, education, income, region of residence, residing in a metropolitan statistical area, health insurance coverage, and having a usual source of care. The model was then applied to the National Health Interview Survey data.
With respect to mammography rates, the covariates explained more than the difference between screening rates for non-Hispanic white women compared to both African-Americans and Hispanics. This suggests that without the covariate differences, more minority groups would participate in mammography screening than white women. This finding is consistent with the NHDR data analysis that found higher rates of screening in certain racial and ethnic subgroups. For other screening tests, including those for colon and cervical cancer, the results left differences unexplained, particularly for Hispanic women. These differences might be explained by more intangible factors such as cultural beliefs and misconceptions or they could simply be a result of differing risk factors and comorbidities.
While adjustments for socioeconomic status may reduce some of the cancer care disparities among racial/ethnic minorities, discrepancies in screening rates, advanced-stage diagnosis, and mortality are not completely explained by this variable. An additional factor closely related to socioeconomic status is health-care access. Though related, the two factors demonstrate independent activity.
Lower mammography rates and differences in the receipt of timely and adequate breast cancer treatment have been used as surrogates for health-care access. Health insurance is another way to assess health-care access. A lack of health insurance is more common among minority women and has been found to correlate with lower use of screening. One study in Boston found that 16% of individuals with insurance underwent annual mammography during the study period, compared to only 6% of those who lacked coverage. Other studies have approached the access question by looking at differences in relapse rates and survival between racial groups with similar access to care.
Du and colleagues addressed this with a population receiving care at the Karmanos Cancer Institute, an NCI-designated Comprehensive Cancer Center affiliated with Wayne State University and the Detroit Medical Center. African-American women were more likely to present with stage III cancer (P = .001) and more likely to use Medicaid (P < .001) compared to white women. In addition, African-American women consistently had a greater number of comorbidities. When adjusted for these differences, there were no significant differences in treatments and cost of care between the two groups. In addition, the investigators found no differences in outcomes, relapse rates, or periods of disease-free survival.
Taken together, these results suggest that access to care may indeed play a role in the increased mortality experienced by many African-American women with breast cancer. However, other studies have suggested that when comparable care is available, mortality is still higher for African-American women. In such cases, the explanation may rest on other differences, including tumor biology differences. For instance, in the same study by Du et al, African-Americans were more likely to have hormone receptor-negative breast cancer (P < .001). Hormone receptor negativity is often associated with a more aggressive tumor behavior compared to hormone receptor-positive breast cancers, which typically have a more indolent course.
Interventions for Underserved Populations
Although barriers and facilitators to cancer screening and treatment are multifactorial and have been studied across multiple levels of the socioeconomic framework, few studies have examined ways to employ effective interventions for historically underserved populations. For instance, the effect of patient navigation on mammography utilization is just being studied in racial/ethnic minority populations. One must also consider the impact of whether patients choose to obtain health care from providers of their own race/ethnicity. A recent study found that although African-American physicians account for less than 5% of all physicians in the United States, these physicians provide care for 25% of African-American patients.
If part of bridging the gap in health care among racial/ethnic minorities is access to providers of their own race/ethnicity, the implications are daunting. What measures are needed to increase the number of minority health-care professionals? Beyond training, should the practice of a minority health-care professional be matched to a specific area of similar race/ethnicity? How will such allocation be perceived, accepted, or even accomplished?