Charting the Future of Cancer Health Disparities Research—Letter
Authors: Philip E. Castle
Journal: Cancer Research (2018)

A recent special report proposed a road map for cancer health disparities research (1). Research on integrated strategies to address multi-cancer health disparities might also be added to this road map.Recently published data highlight large U.S. county-to-county variability in the mortality due to specific cancers (2), suggestive of health disparities across multiple cancers in the United States as previously noted by Freeman and colleagues (3). Table 1 shows the county-specific cancer–cancer mortality (2) and cancer mortality–income per capita (ICP; ref. 4) correlations for the leading cancer sites causing death in the United States in 2014 (5) with each other and with cervical cancer, a known marker of cancer health disparities (3). Cervical cancer mortality was the most strongly negatively correlated with ICP. Cervical cancer mortality best correlated (ρ ≥ 0.65) with mortality due to cancers of the colorectal cancer, liver, lung, and breast but was poorly correlated (ρ ≤ 0.15) with uterine, bladder, brain and nervous system, and non-Hodgkin lymphoma. Those correlated cancers were also negatively associated with ICP. Similar relationships and patterns were observed at the state level (data not shown).Two screen-preventable cancers, cervical and colorectal cancers, are correlated with each other and with income at county and state levels (Fig. 1). Cervical cancer mortality in females is even correlated with colorectal cancer mortality in males (ρ = 0.67) at the county level. Although these analyses are limited by the nature of using correlative data and therefore do not prove causality, they do suggest that excessive burden of preventable and controllable cancers may cluster where resources are limited, whether in specific U.S. counties or globally (6). Additional investigations in the relationship between cancer mortality and other county-level metrics of health, such as those provided by the Robert Woods Johnson Foundation (http://www.countyhealthrankings.org/) may provide additional insights into the causes of these health disparities.These and other data (7) highlight the need to conduct research on integrated health service delivery, not just to the poorest individuals but perhaps also to their families and communities who may also experience an excessive burden of preventable and controllable cancers due to the same barriers to access cancer prevention and control services. Human and system barriers that prevent medically underserved women from getting cervical cancer screening are likely also to prevent access to health education and services for prevention and control of other cancers to their families and communities. Socioeconomic status is strongly linked to access to cancer prevention and control continuum of care (3, 8–11).Thus, community-based outreach projects that have focused on overcoming the barriers related to one cancer disparity might consider integrating multiple interventions collectively to reduce the burden due to the cluster of cancers that disproportionately affect these populations. For example, to underserved individuals and/or families living in high cancer-burden counties, community outreach could provide self-collection kits for (i) vaginal specimens for human papillomavirus (HPV) testing for cervical cancer screening of age-eligible women; (ii) fecal specimens for fecal immunochemical/fecal occult blood testing (FIT/FOBT) for colorectal cancer screening of both age-eligible men and women in the household; and (iii) saliva for immunoassay testing for hepatitis C virus (HCV) screening (to prevent 20% of liver cancer; ref. 12). Compared with using cervical specimens collected by a provider during a pelvic exam, self-collection of vaginal specimens has been demonstrated to have equal clinical performance when a PCR-based assay is used for HPV testing (13) and has better acceptance/greater compliance in underserved populations (14, 15). Home-based fecal collection increases adherence to annual screening by FIT/FOBT for colorectal cancer screening (16). HCV antibody testing of oral specimens has shown promising clinical performance compared with laboratory-based testing (17). Tobacco use cessation/prevention counseling for all and HPV vaccination for adolescents might also be included in the outreach program to those families and communities.Such a strategy(ies) to target the prevention and control of multiple cancers, or even multiple noncommunicable diseases (18), once identified and validated through research, might be more cost-effective and more effective than targeting individual cancers in medically underserved populations. Further research on how best to deliver integrated strategies to reach underserved populations for cancer prevention and control is warranted.No potential conflicts of interest were disclosed.