A 50-year review of colorectal cancer in African Americans: implications for prevention and treatment

Colorectal Cancer: In the Pursuit of Health Equity

Colorectal cancer mortality has decreased considerably following the adoption of national screening programs, yet, within at-risk subgroups, there continue to be measurable differences in clinical outcomes from variations in screening, receipt of chemotherapy, radiation or surgery, access to clinical trials, research participation, and survivorship. These disparities are well-described and some have worsened over time. Disparities identified have included race and ethnicity, age (specifically young adults), socioeconomic status, insurance access, geography, and environmental exposures. In the context of the COVID-19 pandemic, colorectal cancer care has necessarily shifted dramatically, with broad, immediate uptake of telemedicine, transition to oral medications when feasible, and considerations for sequence of treatment. However, it has additionally marginalized patients with colorectal cancer with historically disparate cancer-specific outcomes; among them, uninsured, low-income, immigrant, and ethnic-minority patients-all of whom are more likely to become infected, be hospitalized, and die of either COVID-19 or colorectal cancer. Herein, we outline measurable disparities, review implemented solutions, and define strategies toward ensuring that all have a fair and just opportunity to be as healthy as possible.

Maternal stress and early-onset colorectal cancer

Early-onset colorectal cancer (EOCRC) is defined as colorectal cancer (CRC) diagnosed before the age of 50. Alarmingly, there has been a significant increase in EOCRC diagnoses' worldwide over the past several decades. Emerging data suggest EOCRCs have distinguishing clinical, pathological, biological and molecular features; and thus, are a fundamentally different subtype of CRCs. Unfortunately, there is no simple explanation for the causes of EOCRC. Scientifically rigorous studies are needed to determine what may be driving the challenging epidemiology of EOCRC. We contend here that a reasonable hypothesis is that prenatal risk factors such as maternal stress and associated sleeping disorders influence offspring epigenetic make-up, and shape immune system and gut health contributing to an increased risk for EOCRC.

Racial Differences in Cancer Susceptibility and Survival: More Than the Color of the Skin?

Epidemiological studies point to race as a determining factor in cancer susceptibility. In US registries recording cancer incidence and survival by race (distinguishing 'black versus white'), individuals of African ancestry have a globally increased risk of malignancies compared with Caucasians and Asian Americans. Differences in socioeconomic status and health-care access play a key role. However, the lesser disease susceptibility of Hispanic populations with comparable lifestyles and socioeconomic status as African Americans (Hispanic paradox) points to the concomitant importance of genetic determinants. Here, we overview the molecular basis of racial disparity in cancer susceptibility ranging from genetic polymorphisms and cancer-driver gene mutations to obesity, chronic inflammation, and immune responses. We discuss implications for race-adapted cancer screening programs and clinical trials to reduce disparities in cancer burden.

Decreasing Black-White Disparities in Colorectal Cancer Incidence and Stage at Presentation in the United States

Background: There are long-standing black-white disparities in colorectal cancer incidence and outcomes in the United States. Incidence and stage at diagnosis reflect the impact of national efforts directed at colorectal cancer prevention and control. We aimed to evaluate trends in black-white disparities in both indicators over four decades to inform the future direction of prevention and control efforts.Methods: We used Surveillance, Epidemiology, & End Results (SEER) data to identify whites and blacks with histologically confirmed colorectal cancer from January 1, 1975 through December 31, 2012. We calculated the age-adjusted incidence and the proportion of cases presenting in late stage by race and year. We then calculated the annual percentage change (APC) and average APC for each indicator by race, examined changes in indicators over time, and calculated the incidence disparity for each year.Results: There were 440,144 colorectal cancer cases from 1975 to 2012. The overall incidence decreased by 1.35% and 0.46% per year for whites and blacks, respectively. Although the disparity in incidence declined from 2004 to 2012 (APC = -3.88%; P = 0.01), incidence remained higher in blacks in 2012. Late-stage disease declined by 0.27% and 0.45% per year in whites and blacks, respectively. The proportion of late-stage cases became statistically similar in whites and blacks in 2010 (56.60% vs. 56.96%; P = 0.17).Conclusions: Black-white disparities in colorectal cancer incidence and stage at presentation have decreased over time.Impact: Our findings reflect the positive impact of efforts to improve colorectal cancer disparities and emphasize the need for interventions to further reduce the incidence gap. Cancer Epidemiol Biomarkers Prev; 26(5); 762-8. ©2016 AACR.

Racial Differences in Stage IV Colorectal Cancer Survival in Younger and Older Patients

INTRODUCTION

African Americans (AAs) compared with European Americans (EAs) have poorer stage-specific survival from colorectal cancer (CRC). Recent reports have indicated that the racial difference in survival has worsened over time, especially among younger patients. To better characterize this association, we used population-based Surveillance, Epidemiology, and End Results registry data to evaluate the effect of race on stage IV CRC survival in patients aged < 50 and ≥ 50 years.

PATIENTS AND METHODS

The population included 16,782 patients diagnosed with stage IV colon and rectal adenocarcinoma from January 1, 2004 and December 31, 2011. Cox proportional hazards regression was used to evaluate the association between race and other prognostic factors and the risk of death in each age group.

RESULTS

Younger AAs compared with EAs had a greater prevalence of proximal CRC at diagnosis, a factor associated with a significantly greater risk of death in both races. Among patients < 50 years old, AAs had a greater risk of death compared with EAs (hazard ratio, 1.35; 95% confidence interval, 1.20-1.51), which was attenuated in patients ≥ 50 years of age (hazard ratio, 1.10; 95% confidence interval, 1.04-1.16); P for interaction = .01.

CONCLUSION

The results revealed poor overall survival for AAs compared with EAs, especially for those < 50 years of age. The greater prevalence of proximal CRC at diagnosis among younger AAs (vs. EAs) might contribute to the racial difference in survival. Future studies are needed to understand how the colonic location affects the efficacy of treatment regimens.

Addressing Low Colorectal Cancer Screening in African Americans: Using Focus Groups to Inform the Development of Effective Interventions

African Americans have the highest burden of colorectal cancer (CRC) in the United States of America (USA) yet lower CRC screening rates than whites. Although poor screening has prompted efforts to increase screening uptake, there is a persistent need to develop public health interventions in partnership with the African American community. The aim of this study was to conduct focus groups with African Americans to determine preferences for the content and mode of dissemination of culturally tailored CRC screening interventions. In June 2013, 45-75-year-old African Americans were recruited through online advertisements and from an urban Veterans Affairs system to create four focus groups. A semi-structured interview script employing open-ended elicitation was used, and transcripts were analyzed using ATLAS.ti software to code and group data into a concept network. A total of 38 participants (mean age = 54) were enrolled, and 59 ATLAS.ti codes were generated. Commonly reported barriers to screening included perceived invasiveness of colonoscopy, fear of pain, and financial concerns. Facilitators included poor diet/health and desire to prevent CRC. Common sources of health information included media and medical providers. CRC screening information was commonly obtained from medical personnel or media. Participants suggested dissemination of CRC screening education through commercials, billboards, influential African American public figures, Internet, and radio. Participants suggested future interventions include culturally specific information, including details about increased risk, accessing care, and dispelling of myths. Public health interventions to improve CRC screening among African Americans should employ media outlets, emphasize increased risk among African Americans, and address race-specific barriers. Specific recommendations are presented for developing future interventions.

Lymph nodes' evaluation in relation to colorectal cancer staging among African Americans

Background

Lymph nodes’ examination in colorectal cancer (CRC) resection specimens is an important determinant that aids in the accuracy of CRC staging and treatment outcomes. Current guidelines call for the examination of at least 12 lymph nodes (LN) in resected specimens in order to establish accurate staging.

Aim

To investigate lymph nodes’ examination protocol as it relates to accurate CRC staging.

Methods

We reviewed 216 African American CRC patients from 1996–2013 who underwent CRC resection and met inclusion criteria for this study. The number of retrieved LNs, length of resected specimens, tumor grade, stage, location, size and histology were examined.

Results

The cohort study was made of 49 % males, median age was 63 years and 45 % of patients were at stage III and IV. The median (IQR) number of examined LNs was 15 (10–22) and the rate of patients with more than 12 examined LNs was 64 %. There was a gradual increase in the percentage of patients with adequate number (>12) of examined LNs during the study period (from 60 % in 1996–2000 to 84 % in 2010–2013 period, P = 0.014). Adequate LNs resection was neither associated with shift of stage from II to III (P = 0.3) nor with the changes from stage IIIa to IIIc (P = 0.9). Metastatic LNs were observed in 8 % of samples with LNs (>12) vs. 13 % of samples with <12 examined LNs (P = 0.1). Patients that had pre-surgical treatment (chemotherapy and radiotherapy) before surgery had <12 LNs examined. There was also a trend of having more examined lymph nodes in large tumors.

Conclusions

Our study shows that there has been an increase in the number of lymph nodes examined in CRC resections since the advent of the current quality initiative. However this increase does not seem to affect the stage or percentage of metastatic lymph nodes’ detection in CRC patients.

Between-ward disparities in colorectal cancer incidence and screening in Washington DC

This study aims to investigate the incidence and determinants of colorectal cancer (CRC) and its screening in District of Columbia (DC), and identify modifiable risk factors. Data (2000–2009) from the DC Cancer Registry, Behavioral Risk Factor Surveillance System (BRFSS-DC) and Surveillance Epidemiology and End Results (SEER) were used to estimate CRC incidence in eight DC Wards. Risk factors and CRC screening were analyzed using uni-, bi-, and multivariable statistical methods with survey procedures in SAS (version 9.2) including binary, unconditional multivariable logistic regression analysis. Factors measured included stage of diagnosis, age, gender, race/ethnicity, smoking, alcohol, exercise, body weight, health insurance, education, employment, and income. Over the study time, CRC screening increased from 48.4% to 68.6%. Mean age at diagnosis was 67 years. CRC incidence is high in DC. Furthermore, CRC incidence rates in DC below 50 years age were higher than the SEER18 average. Disparities exist between CRC incidence and screening among DC Wards. Identified risk factors for CRC are smoking, obesity, and low physical activity; screening was less prevalent among the uninsured and low socio-economic group. Local variations in CRC occurrence exist and may vary from average national experiences. Identification of local regions which vary from national trends in disease occurrence is important for comprehensive understanding of the disease in the community.

Prognostic factors in relation to racial disparity in advanced colorectal cancer survival

INTRODUCTION

Colorectal cancer mortality rates are significantly greater in AA than in EA individuals, and the disparity is worsening. We investigated the relationship between race and metastatic CRC (mCRC) survival in younger and older patients.

PATIENTS AND METHODS

Using data from the Hollings Cancer Center (Charleston, SC), we studied the role of clinical, pathologic, and treatment-related factors on the disparity in survival. We carried out a retrospective cohort study of 82 mCRC patients (26 AA, 56 EA). The data source was medical record data from June 1, 2004 through May 31, 2008 with follow-up through June 30, 2010. Using Kaplan-Meier methods, we generated median survival time according to race and age (< 61, ≥ 61 years). Cox proportional hazards regression models were used to model the risk of death according to race.

RESULTS

The median age was 56.7 years for AA and 61.6 years for EA patients. Compared with EA, median survival in AA patients was 59% worse in younger patients (12.7 vs. 31.0 months) and 29% worse in older patients (11.7 vs. 16.4 months). The risk of death among younger AA compared with EA patients was 2.45 (95% confidence interval [CI], 1.15-5.23) and among older patients was 1.16 (95% CI, 0.49-2.73).

CONCLUSION

Our results highlight the importance of considering younger age, clinical prognostic markers, and tumor phenotypes as potential sources of the disparity in advanced stage CRC.

DNA Methylation and Colorectal Cancer

Colorectal cancer (CRC) is one of the major cancers in the world and second death-causing cancer in the US. CRC development involves genetic and epigenetic alterations. Changes in DNA methylation status are believed to be involved at different stages of CRC. Promoter silencing via DNA methylation and hypomethylation of oncogenes alter genes' expression, and can be used as a tool for the early detection of colonic lesions. DNA methylation use as diagnostic and prognostic marker has been described for many cancers including CRC. CpG Islands Methylator Phenotype (CIMP) is one of the underlying CRC mechanisms. This review aims to define methylation signatures in CRC. The analysis of DNA methylation profile in combination with the pathological diagnosis would be useful in predicting CRC tumors' evolution and their prognostic behavior.

An integrative CGH, MSI and candidate genes methylation analysis of colorectal tumors

BACKGROUND

Different DNA aberrations processes can cause colorectal cancer (CRC). Herein, we conducted a comprehensive molecular characterization of 27 CRCs from Iranian patients.

MATERIALS AND METHODS

Array CGH was performed. The MSI phenotype and the methylation status of 15 genes was established using MSP. The CGH data was compared to two established lists of 41 and 68 cancer genes, respectively, and to CGH data from African Americans. A maximum parsimony cladogram based on global aberrations was established.

RESULTS

The number of aberrations seem to depend on the MSI status. MSI-H tumors displayed the lowest number of aberrations. MSP revealed that most markers were methylated, except RNF182 gene. P16 and MLH1 genes were primarily methylated in MSI-H tumors. Seven markers with moderate to high frequency of methylation (SYNE1, MMP2, CD109, EVL, RET, LGR and PTPRD) had very low levels of chromosomal aberrations. All chromosomes were targeted by aberrations with deletions more frequent than amplifications. The most amplified markers were CD248, ERCC6, ERGIC3, GNAS, MMP2, NF1, P2RX7, SFRS6, SLC29A1 and TBX22. Most deletions were noted for ADAM29, CHL1, CSMD3, FBXW7, GALNS, MMP2, NF1, PRKD1, SMAD4 and TP53. Aberrations targeting chromosome X were primarily amplifications in male patients and deletions in female patients. A finding similar to what we reported for African American CRC patients.

CONCLUSION

This first comprehensive analysis of CRC Iranian tumors reveals a high MSI rate. The MSI tumors displayed the lowest level of chromosomal aberrations but high frequency of methylation. The MSI-L were predominantly targeted with chromosomal instability in a way similar to the MSS tumors. The global chromosomal aberration profiles showed many similarities with other populations but also differences that might allow a better understanding of CRC's clinico-pathological specifics in this population.

DNA methylome profiling identifies novel methylated genes in African American patients with colorectal neoplasia

The identification of genes that are differentially methylated in colorectal cancer (CRC) has potential value for both diagnostic and therapeutic interventions specifically in high-risk populations such as African Americans (AAs). However, DNA methylation patterns in CRC, especially in AAs, have not been systematically explored and remain poorly understood. Here, we performed DNA methylome profiling to identify the methylation status of CpG islands within candidate genes involved in critical pathways important in the initiation and development of CRC. We used reduced representation bisulfite sequencing (RRBS) in colorectal cancer and adenoma tissues that were compared with DNA methylome from a healthy AA subject's colon tissue and peripheral blood DNA. The identified methylation markers were validated in fresh frozen CRC tissues and corresponding normal tissues from AA patients diagnosed with CRC at Howard University Hospital. We identified and validated the methylation status of 355 CpG sites located within 16 gene promoter regions associated with CpG islands. Fifty CpG sites located within CpG islands-in genes ATXN7L1 (2), BMP3 (7), EID3 (15), GAS7 (1), GPR75 (24), and TNFAIP2 (1)-were significantly hypermethylated in tumor vs. normal tissues (P<0.05). The methylation status of BMP3, EID3, GAS7, and GPR75 was confirmed in an independent, validation cohort. Ingenuity pathway analysis mapped three of these markers (GAS7, BMP3 and GPR) in the insulin and TGF-β1 network-the two key pathways in CRC. In addition to hypermethylated genes, our analysis also revealed that LINE-1 repeat elements were progressively hypomethylated in the normal-adenoma-cancer sequence. We conclude that DNA methylome profiling based on RRBS is an effective method for screening aberrantly methylated genes in CRC. While previous studies focused on the limited identification of hypermethylated genes, ours is the first study to systematically and comprehensively identify novel hypermethylated genes, as well as hypomethylated LINE-1 sequences, which may serve as potential biomarkers for CRC in African Americans. Our discovered biomarkers were intimately linked to the insulin/TGF-B1 pathway, further strengthening the association of diabetic disorders with colon oncogenic transformation.

Racial disparities in advanced-stage colorectal cancer survival

PURPOSE

African-Americans (AA) have a higher incidence of and lower survival from colorectal cancer (CRC) compared with European Americans (EA). In the present study, statewide, population-based data from South Carolina Central Cancer Registry are used to investigate the relationship between race and age on advanced-stage CRC survival.

METHODS

The study population was comprised of 3,865 advanced pathologically documented colon and rectal adenocarcinoma cases diagnosed between 01 January 1996 and 31 December 2006: 2,673 (69 %) EA and 1,192 (31 %) AA. Kaplan-Meier methods were used to generate median survival time and corresponding 95 % confidence intervals (CI) by race, age, and gender. Factors associated with survival were evaluated by fitting Cox proportional hazards regression models to generate hazard ratios (HR) and 95 % CI.

RESULTS

We observed a significant interaction between race and age on CRC survival (p = 0.04). Among younger patients (<50 years), AA race was associated with a 1.34 times (95 % CI 1.06-1.71) higher risk of death compared with EA. Among older patients, we observed a modest increase in risk of death among AA men compared with EA [HR 1.16 (95 % CI 1.01-1.32)] but no difference by race between women [HR 0.94 (95 % CI 0.82-1.08)]. Moreover, we observed that the disparity in survival has worsened over the past 15 years.

CONCLUSIONS

Future studies that integrate clinical, molecular, and treatment-related data are needed for advancing understanding of the racial disparity in CRC survival, especially for those <50 years old.

Case-control study of vitamin D, dickkopf homolog 1 (DKK1) gene methylation, VDR gene polymorphism and the risk of colon adenoma in African Americans

BACKGROUND

There are sparse data on genetic, epigenetic and vitamin D exposure in African Americans (AA) with colon polyp. Consequently, we evaluated serum 25(OH) D levels, vitamin D receptor (VDR) polymorphisms and the methylation status of the tumor suppressor gene dickkopf homolog 1 (DKK1) as risk factors for colon polyp in this population.

METHODS

The case-control study consisted of 93 patients with colon polyp (cases) and 187 healthy individuals (controls) at Howard University Hospital. Serum levels of 25(OH)D (including D3, D2, and total) were measured by liquid chromatography-mass spectrometry. DNA analysis focused on 49 single nucleotide polymorphisms (SNPs) in the VDR gene. Promoter methylation analysis of DKK1 was also performed. The resulting data were processed in unadjusted and multivariable logistic regression analyses.

RESULTS

Cases and controls differed in vitamin D status (D(3)<50 nmol/L: Median of 35.5 in cases vs. 36.8 in controls nmol/L; P = 0.05). Low levels of 25(OH)D(3) (<50 nmol/L) were observed in 86% of cases and 68% of controls and it was associated with higher risks of colon polyp (odds ratio of 2.7, 95% confidence interval 1.3-3.4). The SNP analysis showed no association between 46 VDR polymorphisms and colon polyp. The promoter of the DKK1 gene was unmethylated in 96% of the samples.

CONCLUSION

We found an inverse association between serum 25(OH)D(3) and colon polyp in AAs. VDR SNPs and DKK1 methylation were not associated with colon polyp. Vitamin D levels may in part explain the higher incidence of polyp in AAs.

Do colorectal cancer patients understand that their family is at risk?

AIM

The aim of this study was to assess whether patients with colorectal cancer (CRC) are aware of the risk to family members and to test an educational intervention.

METHODS

CRC patients were surveyed regarding their cancer, family history, understanding of familial risk of CRC, and knowledge of existing screening guidelines for their relatives. An educational intervention was mailed to them and 6 months later they were resurveyed.

RESULTS

Of 253 CRC patients who agreed to participate, only 120 (47.4%) knew that their first-degree relatives were at increased risk for CRC. African-American (AA) race, educational background, income, and previous family history of CRC were significant predictive factors on univariate analysis, but only AA race remained significant on multivariate analysis. Two hundred two patients received the educational intervention and were resurveyed. The understanding of family risk did not improve with this intervention.

CONCLUSION

Most CRC patients do not know about their family members' risk. Better educational tools are needed.