Background and PurposeGlobally and in the United States (US), colorectal cancer (CRC) is the second leading cause of cancer-related death, following lung cancer. In addition, there are established racial disparities in incidence and mortality for this disease, where ethnic minority groups have higher incidence and mortality rates. Blacks currently have the second-highest rates of CRC incidence and mortality, are diagnosed at more advanced stages, and have the lowest 5-year survival rates of all racial groups. Multiple influences impact this disparity including area- and individual-level factors. Area-level factors, encompassing social determinants of health (e.g. area-level poverty, housing characteristics, etc.), play a role in disease etiology and outcomes. In addition, timely CRC screening (CRCS) reduces CRC incidence and mortality; however, screening patterns, globally and in the US, are not optimal and differ by race, with ethnic minority groups having low CRCS adherence compared to non-Hispanic whites. Differences in CRCS behaviors and outcomes have been noted for Blacks, a term used to describe, for example, a heterogeneous racial group comprised of US-born Blacks and immigrants from Africa and the Caribbean. While CRCS barriers are well documented for the general population, CRCS barriers are less understood for Blacks and very little is known about CRCS habits and CRCS barriers within this heterogeneous racial group, with limited research including Caribbean immigrants and no known research including African-born immigrants. This dissertation uses a mixed-methods approach to describe CRC incidence, advanced stage at diagnosis, and mortality, CRCS behaviors, and CRCS barriers within the heterogeneous Black population in Philadelphia County, Pennsylvania.
Aim 1. Assess colorectal cancer incidence, advanced stage at diagnosis, and colorectal cancer mortality, overall and among individuals who identify as Black/African American, and contextual disparities in Philadelphia County utilizing data from the Pennsylvania State Cancer Registry (2010–2016) and relevant US Census and American Community Survey data.
Aim 2. Determine colorectal cancer screening adherence for Cancer Prevention Project of Philadelphia (CAP3) participants who self-identify as Black.
Aim 3: Conduct gender-specific focus groups to elucidate the principal barriers to colorectal cancer screening adherence within an average-risk group of adults, ages 45–75, who self-identify as Black or African American, in an urban population.
Methods
Aim 1. Using an ecological design, descriptive, geographic spatial clustering and hierarchical logistic regression analyses were done to describe CRC incidence, advanced stage at diagnosis, and colorectal cancer-specific mortality in Philadelphia County at the individual- and area-level. CRC incidence, stage at diagnosis, and mortality data for histologically confirmed CRC cases were obtained from the Pennsylvania Cancer Registry from 2010 to 2016, with mortality data including deaths through 2020. Area-level data were retrieved from the US Census Bureau, American Community Survey, etc. Individual- and area-level descriptive characteristics were calculated for all CRC incident cases, cases diagnosed at advanced stage, and colorectal cancer-specific mortality, overall and for whites and Blacks. Geographic clusters with higher-than-expected relative risk for each outcome of interest at the census tract level (HRCT) were identified and individual- and area-level descriptive statistics were calculated for Blacks, overall and by HRCT status. Adjusted hierarchical logistic regression analyses using backward stepwise elimination with model quasi-information criterion was performed to identify potential predictors of HRCTs for CRC incidence and advanced stage at diagnosis.
Aim 2. Cross-sectional data from age-eligible adults, 50–75 years (N=357) participating in the ongoing CAP3 study was used to measure CRCS prevalence and adherence and region of birth (e.g., Caribbean-, African-, US-born). Prevalence and adherence were based on contemporaneous US Preventive Services Task Force guidelines. Descriptive statistics and adjusted prevalence and adherence proportions were calculated by region of birth. Adjusted logistic regression models were performed to assess the association between region of birth and overall CRCS and modality-specific adherence.
Aim 3. To assess CRCS barriers, we conducted six sex-specific focus groups (n=3 female, n=3 male) with individuals, ages 45-75, who self-identified as Black (i.e., US-, Caribbean, or African-born) and were. Focus groups were held in person and via Zoom, recorded and transcribed verbatim. Codes were developed using coding consensus, co-occurrence, and comparison and open, axial, and selective coding rooted in grounded theory. Dedoose was used to determine CRCS barrier themes as well as general and modality-specific barriers by sex and by region of birth.
Results
Aim 1. In Philadelphia County, there were 4,641 CRC incident cases, of which 2,086 (44.9%) were non-Hispanic Black (NHB), and 2,555 (53.1%) were white. Mean age at diagnosis for CRC incidence (65.0 vs. 68.9 years), advanced stage at diagnosis (63.2 vs. 67.4 years), and colorectal cancer-specific mortality (67.5 vs. 71.7 years) was lower for Blacks compared to whites (p-value<0.001). Blacks were also diagnosed at a more advanced stage (25.0% vs. 22.4%, p-value=0.038) or unknown stage (8.01% vs. 5.64%, p-value=0.001). For each outcome, when compared to whites, higher proportions of Blacks lived in areas with higher proportions of markers of low socio-economic status and lower proportions of CRCS adherence. Geographic clusters at a higher-than-expected risk of CRC incidence were found in Northeast Philadelphia, North Philadelphia, West Philadelphia, and Southwest Philadelphia. Geographic clusters at a higher-than-expected risk of CRC diagnosed at an advanced stage and colorectal cancer-specific mortality overlapped and were in the North, Kensington, and Southwest neighborhoods of Philadelphia. Area-level NHB, the primary independent variable of interest, reduced the odds of HRCT for CRC incidence (OR: 0.971, 95% CI: 0.960, 0.983) and was not significantly associated with HRCT for advanced stage at diagnosis. In addition, after adjustment, for every one-unit increase in the percent of area-level foreign-born Blacks, there was 1.17-increased odds of being a HRCT for CRC incidence (95% CI: 1.07, 1.28). Similarly, there was a significant positive association with area-level foreign-born Black and being in a HRCT for advanced stage at diagnosis (OR: 1.15, 95% CI: 1.05, 1.26). Other area-level variables that were associated with HRCT for CRC incidence were median rent, percent of mortgaged housing units, and per capita income, which reduced the odds of being a HRCT; Percent of mortgaged housing units also reduced the odds of being a HRCT for advanced stage at diagnosis. Further, CRCS adherence reduced the odds of being a HRCT for advanced stage at diagnosis by approximately 15% (OR: 0.849, 95% CI: 0.791, 0.911).
Aim 2. Respondents were 69.5% female, 43.3% married/living with a partner, and 38.4% had <$25,000 annual income. Overall, 78.2% reported past CRCS; however, stool test had the lowest prevalence overall (34.6%). Caribbean (95.0%) and African immigrants (90.2%) had a higher prevalence of overall CRCS compared to US-born Blacks (59.2%) (p-value <0.001). African immigrants were five times more likely to adhere to overall CRCS than US-born Blacks (OR: 5.25, 95% CI: 1.34, 20.6). Immigrants had higher odds of being adherent to colonoscopy (Caribbean=OR: 6.84, 95% CI: 1.49, 31.5; African =OR: 7.15, 95% CI: 1.27, 40.3) compared to US-born Blacks.
Aim 3. The majority of focus group participants were 60–64 years old and 72% were immigrants (41% African-born, 31% Caribbean-born). Most participants had had CRCS, but 45% were non-adherent to national CRCS guidelines. Overall, lack of knowledge/awareness, fear, and a sense of feeling healthy and subsequently not seeing the need for CRCS emerged as overarching themes to CRCS barriers. General barriers differed by gender: for women lack of physician recommendation or explanation of CRCS was important and for men not knowing anyone with a history of CRCS was commonly cited. .” Differences in modality-specific barriers by gender were also noted. Barriers also differed by region of birth. US-born Blacks described lack of community advocacy promoting CRC and CRCS awareness as a barrier. African-born Blacks expressed lack of routine CRCS and utilization of preventive medicine in their native country as barriers. US- and Caribbean-born Black males, communicated that discussing CRCS was taboo, which was tied to hegemonic masculinity leading to a lack of conversations about CRC and CRCS. The use of traditional home remedies emerged as a barrier given respondents felt these remedies would aid in preventing CRC thereby reducing the need for CRCS. Immigrant Blacks also described limited insurance coverage due to their citizenship status.
Conclusions
This dissertation provides the first known insight into various outcomes across the colorectal cancer continuum for the heterogeneous Black population including the growing immigrant Black subgroups in Philadelphia County. To reduce CRC incidence and mortality, interventions and resources to increase CRCS uptake need to target geographic locations with higher percentages of foreign-born Blacks, lower CRCS adherence, and areas with worse socio-economic markers. Also, while Black immigrants had higher CRCS adherence compared to US-born Blacks, CRCS is still sub-optimal in the Black population. Further, CRCS barriers exist and differ by gender, and importantly, there are nuanced barriers by region of birth. Thus, efforts to increase CRCS should address the common and unique barriers and promote stool-based testing, as stool test adherence was low and focus group participants were unfamiliar with this modality as it is not widely promoted or available in clinical practice. In short, these findings across the colorectal cancer continuum should be taken into account for resource allocation and when designing targeted or tailored interventions to promote CRCS uptake for the heterogeneous Black population, which would reduce CRC incidence, late-stage diagnosis, and mortality. / Epidemiology
| Identifer | oai:union.ndltd.org:TEMPLE/oai:scholarshare.temple.edu:20.500.12613/10321 |
| Date | 05 1900 |
| Creators | Blackman, Elizabeth, 0000-0001-5965-8016 |
| Contributors | Jones, Resa M., Dumenci, Levent, Ragin, Camille, Ashing, Kimlin Tam, Cobran, Ewan |
| Publisher | Temple University. Libraries |
| Source Sets | Temple University |
| Language | English |
| Detected Language | English |
| Type | Thesis/Dissertation, Text |
| Format | 340 pages |
| Rights | IN COPYRIGHT- This Rights Statement can be used for an Item that is in copyright. Using this statement implies that the organization making this Item available has determined that the Item is in copyright and either is the rights-holder, has obtained permission from the rights-holder(s) to make their Work(s) available, or makes the Item available under an exception or limitation to copyright (including Fair Use) that entitles it to make the Item available., http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | http://dx.doi.org/10.34944/dspace/10283, Theses and Dissertations |
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