Potential differences in breast cancer risk factors based on CYP1A1 MspI and African-American-specific genotypes.

OBJECTIVES: Recent studies show that an Mspl polymorphism in the 3'-noncoding region of the CYP1A1 gene is associated with breast cancer in African-American women but not in Caucasian women. In addition, an African-American-specific (AAS) polymorphism is located in intron 7 of this gene. We hypothesized that the AAS polymorphism may partially account for this race-specific association and that different environmental risk factor profiles are a function of genotype status. We studied both CYP1A1 polymorphisms to determine if African-American women with these variants have breast cancer risk factor profiles that are different from those of other African-American women. METHODS: A case-control analysis was conducted. Cases were 304 African-American patients pathologically diagnosed with breast cancer from 1995 to 1998 who lived in three Tennessee counties. Controls were 305 African-American women without breast cancer, selected through random-digit dialing and frequency matched to cases by age and county. Information on risk factors was collected through telephone interviews. Tumor tissue samples were collected for CYP1A1 genotyping. There were 215 and 188 cases with the Mspl and AAS polymorphisms measured respectively. RESULTS: Our study results suggest that some risk factors for breast cancer are dependent upon CYP1A1 genotype. Specifically, low intakes of folate, methionine, vitamin C, and vitamin E appear to increase the risk of breast cancer in individuals with the AAS variant: the odds ratio (OR) estimates and 95% confidence intervals were 2.10 and 0.99-4.44 for folate, 1.96 and 0.91-4.23 for methionine, 2.13 and 1.00-4.53 for vitamin C, and 2.43 and 1.12-5.25 for vitamin E. Such associations are stronger for tumors with both AAS and MspI polymorphisms: the OR estimates increased to >6.00 for all these variables except for vitamin C. CONCLUSIONS: This study found that methyl-deficient diets and antioxidant vitamins may be related to the risk of breast cancer as a function of the Mspl and AAS genotpyes. Our results are preliminary because of a small number of cases with polymorphisms at both sites, but they indicate the need for large-scale epidemiologic studies of both African-American and Caucasian women that include genotype information from controls with more detailed information on risk factors.

Body mass index and breast cancer risk in African American women.

PURPOSE: Studies of the relationship between body mass index (BMI) and breast cancer in African American women have been few. We conducted a case-control study to examine whether BMI is associated with risk of breast cancer in this population. METHODS: Cases were 304 women diagnosed with breast cancer at the ages of 20 to 64 years. Controls were 305 women without a history of breast cancer. Telephone interviews were conducted to collect data on history of exposure to various factors at or before the date of diagnosis in cases or equivalent date in controls (reference date). Using logistic regression, we compared cases and controls in BMI at age 18, BMI at the reference date, and change in BMI between the two dates. RESULTS: Using BMI at reference date, we found an odds ratio (OR) of 1.75 (95% confidence interval [CI], 1.02-3.02) and 2.32 (95% CI, 1.33-4.03) for women with BMI of 25 to 29.9 and 30 or higher, respectively, compared with women having BMI lower than 25. The corresponding OR estimates for BMI at age 18 were not significantly different from the unity. The average annual change in BMI between age 18 and date of diagnosis or reference date was associated with breast cancer risk, as shown that more BMI change tended to increase breast cancer risk compared with the baseline quartile of change. When data were analyzed by menopausal status, the association was found for both post-menopausal and pre-menopausal tumors for BMI at reference date but not for BMI at age 18. There was a higher risk for more annual BMI change compared with the baseline for both pre-menopausal and post-menopausal women. CONCLUSION: Our results suggest that BMI at reference date and change in BMI were associated with increased risk of breast cancer in African American women, and the association might be found for both post-menopausal and pre-menopausal tumors.

Methyl-group dietary intake and risk of breast cancer among African-American women: a case-control study by methylation status of the estrogen receptor alpha genes.

OBJECTIVES: Recent molecular studies show that the absence of estrogen receptor (ER) alpha gene expression in breast cancer is associated with methylation of the CpG island located in the 5' region and the first exon of the ER alpha gene. Because CpG island methylation is an early event in carcinogenesis and because a methyl-deficient diet may lead to abnormal DNA methylation including CpG island methylation, we hypothesized that a methyl-deficient diet is more likely to be associated with breast cancer with methylated ER alpha gene CpG islands. This study aimed to test this hypothesis in African-American women using a case-control design. METHODS: Cases were 304 African-American women pathologically diagnosed with breast cancer during 1995-1998 who lived in three Tennessee counties. Controls were 305 African-American women without breast cancer, who were selected through random-digit dialing and frequency matched to cases by 5-year age range and county of residence. Information on dietary intake and other risk factors was collected through telephone interviews. Dietary methyl-components were defined based on folate and methionine intakes and alcohol consumption. Tumor tissue samples were collected for measuring methylation status of the ER alpha gene. RESULTS: Our results showed that the odds ratio (OR) estimates for lower dietary folate intake were 2.0 (95% confidence interval, CI: 0.8-4.8) for cases with a methylated ER alpha gene, 0.6 (95% CI: 0.3-1.5) for cases with an unmethylated ER alpha gene, and 1.6 (95% CI: 0.7-3.8) for cases with unknown methylation status (presumably including cases with both methylated and un-methylated genes). However, low methionine intake appeared more likely to be associated with tumors with unknown methylation status and high level of alcohol consumption seemed more likely to be related to tumors with un-methylated genes. CONCLUSIONS: These results did not show a pattern consistent with the study hypothesis that methyl-deficient diets are more likely related to breast cancer with a methylated ER gene.

A case-control study of menstrual factors in relation to breast cancer risk in African-American women.

Menstrual characteristics may serve as surrogate measures of endogenous estrogen and may be related to breast cancer risk. No previous studies have systematically investigated menstrual factors in relation to the disease in African-American women. This case-control study is aimed to assess the relationship between menstrual factors and breast cancer in African-American women. Cases were 304 African-American women, aged 20-64 living in three Tennessee counties, diagnosed with breast cancer between 1995 and 1998. Controls were selected through random-digit dialing and frequency matched to cases (n=305). Phone interviews were conducted on menstrual factors--age at menarche, time to regularity, cycle length, flow length, age at menopause--and other risk factors. Logistic regression showed that compared to women with short cycle length (<28 days), women with average cycle length > or =28 had decreased risk of breast cancer (odds ratio (OR)=0.60, 95% confidence interval (CI), 0.38-0.94). Dose-response analyses showed decreasing risk with longer cycle length. Results by menopausal status revealed an inverse relationship was shown only in postmenopausal women. No significant associations were observed for other menstrual factors. Findings suggest that cycle length has an inverse association with breast cancer in African-American women that may primarily exist for post-menopausal tumors.

Use of electric bedding devices and risk of breast cancer in African-American women.

In this case-control study, the authors aimed to examine whether use of an electric bedding device increased breast cancer risk in African-American women. Cases were 304 African-American patients diagnosed with breast cancer during 1995-1998 who were aged 20-64 years and lived in one of three Tennessee counties. Controls were 305 African-American women without breast cancer who were selected through random digit dialing and frequency-matched to cases by age and county. Information on the use of an electric blanket or heated water bed and other risk factors was collected through telephone interviews. Breast cancer risk associated with use of an electric bedding device increased with the number of years of use, the number of seasons of use, and the length of time of use during sleep. When women who used an electric bedding device for more than 6 months per year (and therefore were more likely to have used a heated water bed, which generates lower magnetic fields) were excluded, the corresponding dose-response relations were more striking. Similar trends in dose response were shown in both premenopausal and postmenopausal women and for both estrogen receptor-positive and estrogen receptor-negative tumors. The use of electric bedding devices may increase breast cancer risk in African-American women aged 20-64 years. Such an association might not vary substantially by menopausal status or estrogen receptor status.

The relationship between menstrual factors and breast cancer according to estrogen receptor status of tumor: a case-control study in African-American women.

BACKGROUND: Exposure to estrogen is a risk factor for breast cancer. Since estrogen executes its effect through estrogen receptors (ERs), the relationship between menstrual factors, which are estrogen-related, and breast cancer may be different depending upon ER status of tumors. This case-control study aimed to examine such a relationship according to ER status of breast cancer in African-American women. METHODS: Cases were 304 African-American patients pathologically diagnosed with breast cancer during 1995-1998, who were 20-64 years old and lived in 3 Tennessee counties. Controls were 305 African-American women without breast cancer, selected through random-digit dialing and frequency matched to cases by age and county. Information on menstrual factors (age at menarche, age at menopause, time from menarche to menstrual regularity, cycle length, and length of flow) and other risk factors were collected through telephone interviews. Estrogen receptor status of tumor samples was defined based on immunohistochemical measurement. Logistic regression analysis was used to calculate odds ratios and 95% confidence interval (CI). RESULTS: Compared to women with an average cycle length less than 28 days, the risks of breast cancer for those with longer length were 0.62 (95% CI, 0.36-1.06) and 0.56 (95% CI, 0.32-1.00) for ER-positive and ER-negative tumors, respectively. The corresponding odds ratio (OR) estimates were 0.42 (95% CI, 0.20-0.86) and 0.38 (95% CI, 0.16-0.90) for postmenopausal women. Other menstrual factors were not significantly associated with breast cancer for either ER status. CONCLUSIONS: Our results did not show a different menstrual factor/breast cancer relationship in terms of ER status in African-American women, although there might be an association between menstrual cycle length and the disease.

An intervention study on screening for breast cancer among single African-American women aged 65 and older.

BACKGROUND: Older African-American women with single marital status are least likely to use screening procedures. This study aimed to evaluate a breast screening intervention program conducted in this population. METHODS: Ten public housing complexes were randomly assigned to either the intervention or the control group. African-American women aged 65 and over were recruited into the study if they were widowed, divorced, separated, or never married and did not have a history of breast cancer (n = 325). The intervention program was delivered by lay health educators at the participant's apartment and was designed to increase knowledge about breast screening, reduce psychological problems, and increase support from significant others. Breast-screening-related cognition and behavior were measured at baseline and at 1 and 2 years postintervention. RESULTS: Comparisons of the preintervention and postintervention measurements showed that while the proportion of women who had a clinical breast examination or mammogram in the preceding year was decreased at 1 year postintervention in the control group, it was increased in the intervention group. However, the differences did not reach a significant level. No consistent patterns could be found in changes of breast self-examination and variables in knowledge, attitudes, and beliefs. When analyses were restricted to women whose significant others had provided information or help on breast screening, results were better, but the differences between the intervention and control groups still did not reach statistical significance. CONCLUSIONS: These results did not suggest significant effects of an intervention program that used lay health educators to promote breast cancer screening in older single African-American women.