Combined influence of genetic and dietary factors on colorectal cancer incidence in Japanese Americans

Colorectal cancer (CRC) rates for Japanese migrants to the United States increased rapidly to surpass the level of the host population. CRC rates for the Japanese in Hawaii and California are now the highest in the world. Rates for this disease have also increased in Japan, presumably as the result of the westernization of the diet. A series of population-based studies in Hawaii was undertaken to determine which dietary factors are responsible for this remarkable susceptibility of the Japanese to CRC and whether genetic factors are also involved. A first case-control study suggested that a high intake of red meat is a major risk factor for the disease in Hawaii Japanese men and that family history of CRC among first-degree relatives may strongly modify this association. A case-control family study is currently being completed to explore further the interaction between family history and the intake of red meat after adjustment for environmental covariates among family members. Also, a segregation analysis will guide gene discovery studies among high-risk Japanese families being recruited in the Cooperative Family Registry for Colorectal Cancer Studies. Retrospective and prospective studies are also ongoing to test associations of CRC with specific polymorphisms in genes controlling the metabolic activation or detoxification of the carcinogens associated with a diet high in red meat. Preliminary results suggest an association of the combined rapid NAT2 genotype and rapid CYP1A2 phenotype with CRC in individuals consuming well-done red meat. Populations in which dramatic changes in cancer incidence have occurred may offer opportunities to identify gene-environment interactions.

The effect of dietary fat on breast cancer survival among Caucasian and japanese women in Hawaii

182 Japanese and 161 Caucasian breast cancer patients participated in an epidemiologic case-control study from 1975-1980. They were subsequently followed until the end of 1987 to determine their survival status. Among the Japanese, patients with regional or distant disease had a relative risk (RR) of death of 13.0 (95% Confidence Interval (CI), 4.3-39.1) compared to those with in situ or localized disease, and obese patients had a RR of death of 3.5 (95% CI, 1.3-10.0) compared to non-obese subjects. Among the Caucasians, patients with advanced disease had a RR of death of 4.3 (95% CI, 1.8-10.5) compared to those with in situ or localized disease, and patients with a high fat intake had a RR of 3.2 (95% CI, 1.2-8.6) compared to subjects with a low fat intake. Menopausal status (pre- or postmenopausal) and replacement estrogen use were not related to survival from breast cancer in either ethnic group. When Japanese and Caucasian patients were compared with each other, there was no significant difference in survival between them.

Characterisation of familial colorectal cancer Type X, Lynch syndrome, and non-familial colorectal cancer

BACKGROUND

Familial Colorectal Cancer Type X (FCCTX) is defined as individuals with colorectal cancer (CRC) who families meet Amsterdam Criteria-1 (AC1), but whose tumours are DNA-mismatch-repair-proficient, unlike Lynch syndrome (LS). FCCTX does not have an increased risk of extra-colonic cancers. This analysis compares epidemiologic and clinicopathologic features among FCCTX, LS, and 'non-familial' (non-AC1) CRC cases.

METHODS

From the Colon Cancer Family Registry, FCCTX (n=173), LS (n=303), and non-AC1 (n=9603) CRC cases were identified. Questionnaire-based epidemiologic information and CRC pathologic features were compared across case groups using polytomous logistic regression.

RESULTS

Compared with LS, FCCTX cases were less likely to be current (vs never) smokers; have a proximal subsite (vs rectal) tumour; or have mucinous histology, poor differentiation, or tumour-infiltrating lymphocytes. There were no observed differences in co-morbidities or medication usage.

CONCLUSIONS

FCCTX were less likely to be current tobacco users; other exposures were similar between these groups. Histopathologic differences highly suggestive of LS CRCs do not appear to be shared by FCCTX.

Vitamin B6 catabolism and lung cancer risk: results from the Lung Cancer Cohort Consortium (LC3)

BACKGROUND

Increased vitamin B6 catabolism related to inflammation, as measured by the PAr index (the ratio of 4-pyridoxic acid over the sum of pyridoxal and pyridoxal-5'-phosphate), has been positively associated with lung cancer risk in two prospective European studies. However, the extent to which this association translates to more diverse populations is not known.

MATERIALS AND METHODS

For this study, we included 5323 incident lung cancer cases and 5323 controls individually matched by age, sex, and smoking status within each of 20 prospective cohorts from the Lung Cancer Cohort Consortium. Cohort-specific odds ratios (ORs) and 95% confidence intervals (CIs) for the association between PAr and lung cancer risk were calculated using conditional logistic regression and pooled using random-effects models.

RESULTS

PAr was positively associated with lung cancer risk in a dose-response fashion. Comparing the fourth versus first quartiles of PAr resulted in an OR of 1.38 (95% CI: 1.19-1.59) for overall lung cancer risk. The association between PAr and lung cancer risk was most prominent in former smokers (OR: 1.69, 95% CI: 1.36-2.10), men (OR: 1.60, 95% CI: 1.28-2.00), and for cancers diagnosed within 3 years of blood draw (OR: 1.73, 95% CI: 1.34-2.23).

CONCLUSION

Based on pre-diagnostic data from 20 cohorts across 4 continents, this study confirms that increased vitamin B6 catabolism related to inflammation and immune activation is associated with a higher risk of developing lung cancer. Moreover, PAr may be a pre-diagnostic marker of lung cancer rather than a causal factor.

Racial/ethnic disparities in weight or BMI change in adulthood and pancreatic cancer incidence: The multiethnic cohort

INTRODUCTION

Compared to non-Hispanic Whites, Japanese Americans, Native Hawaiians, and African Americans have higher incidences of pancreatic cancer (PCa) that are not entirely explained by rates of obesity but may be explained by weight changes throughout adulthood.

METHODS

The multiethnic cohort is a population-based prospective cohort study that has followed 155,308 participants since its establishment between 1993 and 1996. A total of 1,328 incident cases with invasive PCa were identified through 2015. We conducted separate multivariable Cox proportional hazards models for self-reported weight-change and BMI-change (age 21 to cohort entry) to determine the association with PCa risk, adjusting for potential confounders including weight or BMI at age 21.

RESULTS

The mean age at cohort entry was 59.3 years (SD 8.9). An increased risk of PCa was associated with: 1) weight (HR per10 lbs = 1.06; 95% CI = 1.03-1.09) or BMI (HR per kg/m2  = 1.04; 95% CI = 1.02-1.05) at age 21; and 2) weight (HR per 10 lbs = 1.03; 95% CI = 1.01-1.05) or BMI (HR = 1.02; 95% CI = 1.00-1.03) at cohort entry. We found increased risk of PCa between weight (HR per 10 lbs = 1.03; 95% CI = 1.01-1.05) and BMI (HR per 5 kg/m2  = 1.08; 95% CI = 1.01-1.15) change from age 21 to baseline. There were significant interactions between race/ethnicity and weight (p = 0.008) or BMI (p = 0.03) at baseline, and weight (p = 0.02) or BMI (p = 0.02) change. Weight and BMI change through adulthood significantly increased the risk of PCa for Japanese Americans and Latinos, but not for African American, White, or Hawaiian participants.

CONCLUSION

Our findings indicate that weight or BMI gain has a significant and independent impact on PCa risk, specifically among Latinos and Japanese Americans.

Doneness preferences, meat and meat-derived heterocyclic amines intake, and N-acetyltransferase 2 polymorphisms: association with colorectal adenoma in Japanese Brazilians

Intake of heterocyclic amines (HCAs) and other mutagenic compounds formed during cooking has been hypothesized to be responsible for the positive association observed between red meat and colorectal cancer. We evaluated whether well-done/very well-done preferences for various meat and fish items, higher intakes of meat and fish, and meat-derived and fish-derived HCA are associated with the risk of colorectal adenoma (CRA) in a Japanese-Brazilian population. We selected 302 patients with adenoma and 403 control individuals who underwent total colonoscopy between 2007 and 2013, and collected information on aspects of meat intake using a detailed questionnaire. We also estimated HCA intake of the study participants using an HCA database that matched the cooking methods of this population. Latent class analysis on the basis of response to doneness preferences for different cooking methods of commonly consumed meat and fish items identified four distinct subgroups. Compared with the subgroup characterized by a preference for rare/medium well-done cooking for most meat and fish items, the odds ratio of CRA for the well-done/very well-done preference subgroup was 1.19 (95% confidence interval: 0.51-2.75). High intake of mixed-meat dishes was suggestively associated inversely with CRA, whereas a high intake of poultry was associated positively with CRA. No clear association with intake of total or specific HCAs and no effect modification by N-acetyltransferase 2 acetylation genotype were observed. We found no statistically significant associations between meat and HCA intake and CRA. These findings do not support a positive association between meat and meat-derived HCA intake and the risk of CRA.

Genetic and dietary predictors of CYP2E1 activity: a phenotyping study in Hawaii Japanese using chlorzoxazone

Cytochrome P4502E1 (CYP2E1) is considered to play an important role in the metabolic activation of procarcinogens such as N-nitrosoamines and low molecular weight organic compounds. An RsaI polymorphism is present in the 5'-flanking region of the CYP2E1 gene, which could possibly affect its transcription. However, the relationship between genotype and the phenotypic catalytic activity of the enzyme has not been defined. Also, the effects in humans of specific dietary factors, other than ethanol, which have been shown in animal and in vitro studies to modulate CYP2E1 activity, are unknown. Accordingly, the CYP2E1-mediated metabolism of chlorzoxazone to its 6-hydroxy metabolite was investigated in 50 healthy Japanese of both sexes in Hawaii. The oral clearance of the in vivo probe, the trait measure of CYP2E1 activity, was smaller than that reported in European-Americans. Significantly, after adjustment for age and sex, the oral clearance of chlorzoxazone decreased with the number of variant c2 alleles, and its mean in the c2/c2 genotype (147 ml/min) was statistically lower (P < or = 0.05) than that for either the homozygous wild-type (238 ml/min) or the heterozygote (201 ml/min) genotypes. Stepwise multiple regression analysis indicated that body weight was a major contributor to the interindividual variability in the oral clearance of chlorzoxazone, accounting for 43% of the variance. Consumption of lettuce, broccoli, and black tea explained additional components of the variability (7, 5, and 6%, respectively), as did medication use (3%), age (4%), and CYP2E1 genotype (5%). Overall, 73% of the variance could be accounted for by these variables. Body weight, lettuce, and use of medications were associated with increased CYP2E1 activity, and the other covariates were associated with reduced enzyme function. Because of the role that CYP2E1 plays in procarcinogen activation, especially of N-nitrosamines involved in lung cancer, the identified factors may account in part for observed differences in individual susceptibility to disease and may also have implications for cancer prevention.