Ethnic differences in colorectal cancer among Arab and Jewish neighbors in Israel

Incidence patterns of colorectal cancers in four countries of the Middle East Cancer Consortium (Cyprus, Jordan, Israel, and İzmir, Turkey) compared with those in the United States Surveillance, Epidemiology, and End Results Program

BACKGROUND/AIMS

There are wide variations in colorectal cancer (CRC) incidence across the world. Historically, the highest incidence rates have been reported historically in more developed countries; however, increasing trends have been seen in developing countries. Here, we present the CRC incidence pattern in Cyprus, Israel, Jordan, and İzmir, Turkey, which are countries of the Middle East Cancer Consortium (MECC).

MATERIALS AND METHODS

We analyzed 2005-2010 CRC data from population-based registries and calculated crude and age standardized rates for CRC, colon and rectum subsites, and annual percent changes (APCs) for trends.

RESULTS

The age-adjusted incidence rates (AAIRs) for CRC were the highest in Israeli Jews (IJ) (46.7 for males and 35.5 for females), which exceeded those of the USA Surveillance, Epidemiology, and End Result (SEER) program registries. In both sexes, AAIRs in Cyprus and Israeli Arabs (IA) were close to those in SEER registries. For both sexes, AAIRs in İzmir and Jordan were substantially lower than those in other registries. Statistically significant decreasing trends over time were observed in AAIRs for both sexes in the SEER program (APCs: males, -3.24% and females, -2.54%), whereas the trends varied within the MECC registries. There were decreasing AAIR trends for males in IJ and IA and for females in Cyprus and IJ; APC for females in IJ (-4.29%) was significant. Conversely, increasing trends with the significant APCs were observed in males in İzmir (2.43%) and Jordan (7.57%).

CONCLUSION

MECC countries comprise both high- and low-risk populations for CRCs. However, increasing trends in low-risk populations have been alarming. Thus, the need for implementing tailored primary and secondary prevention programs in the region is essential.

Molecular spectrum of KRAS, NRAS, BRAF, PIK3CA, TP53, and APC somatic gene mutations in Arab patients with colorectal cancer: determination of frequency and distribution pattern

BACKGROUND

The frequency rates of mutations such as KRAS, NRAS, BRAF, and PIK3CA in colorectal cancer (CRC) differ among populations. The aim of this study was to assess mutation frequencies in the Arab population and determine their correlations with certain clinicopathological features.

METHODS

Arab patients from the Arab Gulf region and a population of age- and sex-matched Western patients with CRC whose tumors were evaluated with next-generation sequencing (NGS) were identified and retrospectively reviewed. The mutation rates of KRAS, NRAS, BRAF, PIK3CA, TP53, and APC were recorded, along with clinicopathological features. Other somatic mutation and their rates were also identified. Fisher's exact test was used to determine the association between mutation status and clinical features.

RESULTS

A total of 198 cases were identified; 99 Arab patients and 99 Western patients. Fifty-two point seven percent of Arab patients had stage IV disease at initial presentation, 74.2% had left-sided tumors. Eighty-nine point two percent had tubular adenocarcinoma and 10.8% had mucinous adenocarcinoma. The prevalence rates of KRAS, NRAS, BRAF, PIK3CA, TP53, APC, SMAD, FBXW7 mutations in Arab population were 44.4%, 4%, 4%, 13.1%, 52.5%, 27.3%, 2% and 3% respectively. Compared to 48.4%, 4%, 4%, 12.1%, 47.5%, 24.2%, 11.1% and 0% respectively in matched Western population. Associations between these mutations and patient clinicopathological features were not statistically significant.

CONCLUSIONS

This is the first study to report comprehensive hotspot mutations using NGS in Arab patients with CRC. The frequency of KRAS, NRAS, BRAF, TP53, APC and PIK3CA mutations were similar to reported frequencies in Western population except SMAD4 that had a lower frequency and higher frequency of FBXW7 mutation.

A novel colorectal cancer risk locus at 4q32.2 identified from an international genome-wide association study

Only a fraction of colorectal cancer heritability is explained by known risk-conferring genetic variation. This study was designed to identify novel risk alleles in Europeans. We conducted a genome-wide association study (GWAS) meta-analysis of colorectal cancer in participants from a population-based case-control study in Israel (n = 1616 cases, 1329 controls) and a consortium study from the Colon Cancer Family Registry (n = 1977 cases, 999 controls). We used a two-stage (discovery-replication) GWAS design, followed by a joint meta-analysis. A combined analysis identified a novel susceptibility locus that reached genome-wide significance on chromosome 4q32.2 [rs35509282, risk allele = A (minor allele frequency = 0.09); odds ratio (OR) per risk allele = 1.53; P value = 8.2 × 10(-9); nearest gene = FSTL5]. The direction of the association was consistent across studies. In addition, we confirmed that 14 of 29 previously identified susceptibility variants were significantly associated with risk of colorectal cancer in this study. Genetic variation on chromosome 4q32.2 is significantly associated with risk of colorectal cancer in Ashkenazi Jews and Europeans in this study.

MicroRNA polymorphisms and risk of colorectal cancer

BACKGROUND

miRNAs act as post-transcriptional regulators of gene expression. Genetic variation in miRNA-encoding sequences or their corresponding binding sites may affect the fidelity of the miRNA-mRNA interaction and subsequently alter the risk of cancer development.

METHODS

This study expanded the search for miRNA-related polymorphisms contributing to the etiology of colorectal cancer across the genome using a novel platform, the Axiom miRNA Target Site Genotyping Array (237,858 markers). After quality control, the study included 596 cases and 429 controls from the Molecular Epidemiology of Colorectal Cancer study, a population-based case-control study of colorectal cancer in northern Israel. The association between each marker and colorectal cancer status was examined assuming a log-additive genetic model using logistic regression adjusted for sex, age, and two principal components.

RESULTS

Twenty-three markers had P values less than 5.0E-04, and the most statistically significant association involved rs2985 (chr6:34845648; intronic of UHRF1BP1; OR = 0.66; P = 3.7E-05). Furthermore, this study replicated a previously published risk locus, rs1051690, in the 3'-untranslated region of the insulin receptor gene INSR (OR = 1.38; P = 0.03), with strong evidence of differences in INSR gene expression by genotype.

CONCLUSIONS

This study is the first to examine associations between genetic variation in miRNA target sites and colorectal cancer using a genome-wide approach. Functional studies to identify allele-specific effects on miRNA binding are needed to confirm the regulatory capacity of genetic variation to influence risk of colorectal cancer.

IMPACT

This study demonstrates the potential for an miRNA-targeted genome-wide association study to identify candidate susceptibility loci and prioritize them for functional characterization.

Barriers to colorectal cancer screening in Palestine: a national study in a medically underserved population

BACKGROUND & AIMS

Cultural, religious, and financial barriers can hinder uptake of colorectal cancer (CRC) screening in Arab communities. We aim to understand attitudes and barriers that contribute to the low rate of CRC screening among Palestinians in the West Bank.

METHODS

We performed a national, cross-sectional study of Palestinian adults older than 50 years. A self-administered questionnaire was developed and validated. Data were randomly collected in all major districts of the West Bank. The primary outcome was the willingness to undergo CRC screening. Multivariable logistic regression models were used to assess the strength of association between the primary outcome and its predictors while controlling for possible confounders.

RESULTS

Of 1601 people approached for an interview, 1352 agreed to participate (response rate, 84%). Only 193 had undergone CRC screening (14%); 1069 (79%) agreed to take a fecal occult blood test, 906 (67%) agreed to a colonoscopy examination, and 1098 (81%) were willing to undergo CRC screening if recommended by a physician. Only 194 (14%) said they had been informed about CRC screening by a physician. Urban residents were more likely to be screened for CRC than nonurban residents (odds ratio, 0.73; 95% confidence interval, 0.56-0.93; P = .011). Multivariable analysis showed that lack of education beyond elementary school or familiarity with CRC screening, distrust of Western medicine, religious objection, and finding the test to be embarrassing were all associated with decreased odds of accepting CRC screening.

CONCLUSIONS

Based on a national, cross-sectional study of Palestinian adults, there are many cultural and religious barriers to CRC screening. Improving our understanding of these could increase screening among Arab populations in the Middle East and in Western countries.

Differences in clinical and pathological characteristics of colorectal cancer in Arab as compared to Jewish patients in Northern Israel

The Incidence of colorectal cancer (CRC) differs in different ethnic groups. The aim of this study is to investigate clinical and pathological features of CRC in Arab as compared to Jewish patients in Northern Israel. Clinical and pathological characteristics of 480 patients with CRC treated between 1999 and 2006 were retrospectively reviewed. Eighty-five percent of the patients were Jews and 15% were Arabs. Mean age at diagnosis was 67.1 years in Jews and 58.3 years in Arabs (P < 0.001). Stage I CRC was 17.5% versus 7.2% (P < 0.05), Stage II was 35.5% versus 27.5% (P < 0.01), Stage III was 26% versus 33.3% (P:0 < 0.01) and Stage IV 21% versus 31% (P < 0.01) in Jewish and Arab patients respectively. In 40.6% of Jewish patients, cancer was well differentiated compared to 27.1% of Arab patients (P < 0.01) and poorly differentiated in 5.5% versus 10,4% (P < 0.05). Abdominal pain, constipation and weight loss were more common in Arabs than in Jews (P < 0.05). In conclusion CRC is more advanced, more aggressive and more symptomatic in Arab than in Jewish patients. Arab patients are younger at the time of diagnosis. Screening for CRC should be started at earlier age in the Arab population than the population at large.

Colorectal cancer among Arab-Israeli women--possible reasons for increased incidence and mortality

BACKGROUND

Colorectal cancer (CRC) screening is effective in reducing its incidence by discovering precancerous polyps and detecting early cancer. Evidence indicates lower participation in screening programs among minority ethnic groups. In addition, the Israel Cancer Registry published an increase in the incidence of CRC among Israeli-Arab women. It is important to attempt to understand attitudes toward screening among Israeli-Arab women, assuming it has to do to lack of knowledge and compliance.

METHODS

During the study period, a female team gave lectures in Arabic regarding CRC to women in 16 Arab villages. Prior to the lecture, the participants were asked to complete a questionnaire, obtaining information regarding CRC knowledge and screening. Following the lecture, FOBT kits were distributed. Two weeks later, a telephone survey was performed, regarding whether the FOBT was performed, the result of the test, and, if FOBT was not performed, the reasons for not completing the test.

RESULTS

FOBT was performed by 17.8% prior to the lecture; 61% performed the FOBT following our lecture. Reasons cited for avoiding FOBT: 37% was "afraid of a positive result," 32% avoided performing the test as they were concerned they would be further examined by a male physician; 47.8% concluded that Arab women lack knowledge regarding screening interventions; 23.9% neglect themselves from a health point of view; 11.6% advised that Arab women have no free time to perform tests.

CONCLUSIONS

Israeli-Arab women may be less knowledgeable concerning CRC. Educational efforts must be made to increase awareness and promote benefits of CRC screening, by targeting ethnic minorities and women in Israel.

Smoking, gender, and ethnicity predict somatic BRAF mutations in colorectal cancer

Approximately 5% to 15% of all colorectal cancers (CRC) have an activating BRAF somatic mutation, which may be associated with a distinct risk profile compared with tumors without BRAF mutations. Here, we measured the prevalence and epidemiologic correlates of the BRAF V600E somatic mutation in cases collected as a part of a population-based case-control study of CRC in northern Israel. The prevalence of BRAF V600E was 5.0% in this population, and the mutation was more likely to be found in tumors from cases who were of Ashkenazi Jewish descent [odds ratio (OR), 1.87; 95% confidence interval (95% CI), 1.01-3.47], female (OR, 1.97; P = 1.17-3.31), and older (73.8 years versus 70.3 years; P < 0.001). These results were similar when restricting to only tumors with microsatellite instability. Whether smoking was associated with a BRAF somatic mutation depended on gender. Although men were less likely to have a tumor with a BRAF somatic mutation, men who smoked were much more likely to have a tumor with a somatic BRAF mutation (OR(interaction), 4.95; 95% CI, 1.18-20.83) than women who never smoked. We note the strong heterogeneity in the reported prevalence of the BRAF V600E mutation in studies of different ethnicities, with a lower prevalence in Israel than other Western populations but a higher prevalence among Jewish than non-Jewish Israeli cases. Epidemiologic studies of CRC should incorporate somatic characteristics to fully appreciate risk factors for this disease.

International trends in colorectal cancer incidence rates

BACKGROUND

Previous studies have documented significant variations in colorectal cancer incidence rates and trends regionally and across countries. However, no study has examined the worldwide pattern using the most recently updated incidence data from the IARC.

METHODS

We obtained sex-specific colorectal cancer incidence for 1953-57 through 1998-2002 by cancer registry from Cancer Incidence in Five Continents (CI5) databases. For 51 cancer registries with long-term incidence data, we assessed the change in the incidence rates over the past 20 years by calculating the ratio of the incidence rates in 1998-2002 to that in 1983-87.

RESULTS

Colorectal cancer incidence rates for both males and females statistically significantly increased from 1983-87 to 1998-2002 for 27 of 51 cancer registries considered in the analysis, largely confined to economically transitioning countries including Eastern European countries, most parts of Asia, and select countries of South America. These increases were more prominent for men than for women. We also observed substantial variations in colorectal cancer incidence trends within countries such as Japan. Similarly, trends in Israel and Singapore varied significantly according to ethnicity. The United States is the only country where colorectal cancer incidence rates declined in both males and females.

CONCLUSIONS

Colorectal cancer incidence rates continue to increase in economically transitioning countries, with incidence rates among men in the Czech Republic and Slovakia exceeding the peak incidence observed in the United States and other long-standing developed nations. Targeted prevention and early detection programs could help reverse the trend in these countries.

Young-age onset of colorectal cancer in Israel

AIM

The study was conducted to investigate the differences in clinical-pathological, ethnic, and demographic presentations and the expression of mismatch repair proteins in a cohort of young-onset (</=50 years) versus late-onset Israeli patients (>50 years) with colorectal cancer.

MATERIALS AND METHODS

Clinical, demographic, and histopathological data of patients with colorectal cancer were collected retrospectively from medical records and pathology reports.

RESULTS

Ninety patients, 50 years of age or younger with a mean age of 42 years were compared with a group of 190 patients above 50 years of 50 (see Table 1). Sixty percent of the young-onset patients were females, compared to 40% in the older age group (P = 0.02). Twenty-one percent of the young-onset patients were Arabs as compared to 2% of older-onset patients (P = 0.001). Younger patients displayed a higher percentage of mucinous cancers and a higher percentage of diagnosis at an advanced stage of disease; 40% of young-onset versus 31% of older-onset patients presented Duke's stages C and D (P = 0.02).

CONCLUSIONS

Younger age of onset colorectal cancer in our cohort of Israeli patients is associated with higher percentage of Arab patients, mucinous cancers, female gender, and advanced stage at diagnosis.

Microsatellite instability, MLH1 promoter methylation, and BRAF mutation analysis in sporadic colorectal cancers of different ethnic groups in Israel

BACKGROUND

The molecular mechanisms that underlie colorectal cancer (CRC) include microsatellite instability (MSI), chromosomal instability, and the CpG island methylator phenotype. There is evidence to suggest that CRC incidence varies among different ethnic populations worldwide. The authors of this report hypothesized that environmental factors and lifestyle differences among various ethnic groups may differentially influence the epigenetic regulation of tumor suppressor genes in CRC.

METHODS

In the current study, microdissection and DNA extraction were performed on 128 samples of CRC from Israeli patients (85 Jews and 43 Arabs). MSI analysis, mutL homolog 1 (MLH1) and mutS homolog 2 (MSH2) protein expression levels, and MLH1 promoter methylation were investigated by combined bisulfite restriction analysis. The v-raf murine sarcoma viral oncogene homolog B1 (BRAF) valine-to-glutamic acid mutation at residue 600 was investigated by direct DNA sequencing.

RESULTS

High MSI (MSI-H), MLH1 methylation, and BRAF mutations were observed in 11.6%, 9.4%, and 23.5% of Jews, respectively, and in 16.2%, 17.6%, and 20.9% of Arabs, respectively (P value nonsignificant). MLH1 promoter methylation was observed in 22.6% of microsatellite-stable (MSS) tumors and in 53.8% of MSI-H tumors (P < .015). Extensive methylation (covering both 5' and 3' promoter regions) was present in all MSI-H tumors with loss of MLH1 expression. BRAF mutation was observed in 15.6% and 46.1% of MSS tumors and MSI-H tumors, respectively (P < .007). BRAF mutation was observed in 66%, 22.2%, and 14.7% of patients who had tumors with extensive MLH1 promoter methylation, methylation of the 5' region alone, or without methylation, respectively (P < .006).

CONCLUSIONS

There was no difference in molecular signatures examined between Jewish and Arab patients with CRC in Israel. Extensive promoter methylation was associated with MLH1 inactivation, MSI, and BRAF mutation.

Clinical and pathologic outcomes of colorectal cancer in a multi-ethnic population

BACKGROUND & AIMS

The influence of birthplace on the clinical and pathologic outcomes of colorectal cancer (CRC) in Australia is unknown. Addressing inequalities in health care provision in immigrant groups may improve the overall quality of CRC care.

METHODS

The South Western Sydney Colorectal Tumour Group registry prospectively collects data on new patients with CRC from a population of 800,000. Survival data were cross-linked with the New South Wales population death registry.

RESULTS

From 1997 to 2004 there were 1496 patients (55% males) who were recruited and grouped according to country of birth: Australia, 64%; Southern Europe, 19%; Asia, 12%; and the Middle East, 5%. Significant heterogeneity in CRC characteristics was found, especially in Asians. Compared with Australians, Asians were diagnosed at a younger age (median age, 64 vs 70 y; P < .001, 25.6% were younger than 50 years vs 9.5%; P < .001), had fewer poorly differentiated cancers (8.9% vs 17.7%; P = .004), and fewer metastatic cancers (12.1% vs 21.0%; P = .001). Being Asian-born was associated with improved overall survival independent of age, emergency surgery, grade, and stage (hazard ratio, 0.66; 95% confidence interval, 0.47-0.93; P = 0.02). CRC screening was especially low among Asian- and Middle Eastern-born patients. Complications and treatment were not affected by birthplace, indicating no differences in the provision or acceptance of care based on birthplace.

CONCLUSIONS

Despite an equitable distribution of resources, we found significant heterogeneity in presentations and outcomes according to birthplace, with improved survival in Asian-born patients. The lower rates of screen-detected CRC in Asian- and Middle Eastern-born patients and their younger ages at diagnosis indicate that targeted screening strategies may need to be implemented.

The changing incidence and sites of colorectal cancer in the Israeli Arab population and their clinical implications

Israeli Arabs have been at low risk for colorectal cancer (CRC) and had mainly proximal cancer, but increasing CRC is now noted. We examined this trend and CRC site and compared them to the total Jewish population and to the low-risk Jews of Asian-African origin. Israel Cancer Registry CRC data, 1982-2002, for Arabs and Jews was computed by gender, age and site: rectal cancer included recto-sigmoid junction; "right-sided" CRC included the proximal colon up to and also the splenic flexure. During 1982-2002, Arab CRC trends increased significantly in both sexes due to left-sided CRC (women, p = 0.01; men, p = 0.02) and rectal cancers (p = 0.05). Left-sided CRC increased significantly in both men and women aged > or = 65 years (p = 0.02). Comparing 1982-1984 to 2000-2002, the proportion of right-sided CRC decreased in both genders (p < 0.01) from 39.4 to 27.1% of male CRC, and from 44.8 to 31.3% in females. In general, this pattern of increasing rectal and left-sided CRC had been seen over a decade earlier in Jews of Asian-African origin and then their trend reversed during the last decade. In conclusion, there is a recent trend for left-sided CRC in Israeli Arabs, probably related to their changing life style. These results should influence their cancer preventive lifestyle recommendations, and CRC screening and diagnostic methodologies used.

Racial differences in the anatomical distribution of colorectal cancer: a study of differences between American and Chinese patients

AIM: To compare the racial differences of anatomical distribution of colorectal cancer (CRC) and determine the association of age, gender and time with anatomical distribution between patients from America (white) and China (oriental).

METHODS: Data was collected from 690 consecutive patients in Cleveland Clinic Florida, U.S.A. and 870 consecutive patients in Nan Fang Hospital affiliated to the First Military Medical University, China over the past 11 years from 1990 to 2000. All patients had colorectal adenocarcinoma diagnosed by histology and underwent surgery.

RESULTS: The anatomical subsite distribution of tumor, age and gender were significantly different between white and oriental patients. Lesions in the proximal colon (P < 0.001) were found in 36.3% of white vs 26.0% of oriental patients and cancers located in the distal colon and rectum in 63.7% of white and 74% of oriental patients (P < 0.001). There was a trend towards the redistribution from distal colon and rectum to proximal colon in white males over time, especially in older patients (> 80 years). No significant change of anatomical distribution occurred in white women and Oriental patients. The mean age at diagnosis was 69.0 years in white patients and 48.3 years in Oriental patients (P < 0.001).

CONCLUSION: This is the first study comparing the anatomical distribution of colorectal cancers in whites and Chinese patients. White Americans have a higher risk of proximal CRC and this risk increased with time. The proportion of white males with CRC also increased with time. Chinese patients were more likely to have distal CRC and developed the disease at a significantly earlier age than white patients. These findings have enhanced our understanding of the disease process of colorectal cancer in these two races.