ABSTRACT: Epidemiologic studies have suggested that higher levels of circulating vitamin D may reduce breast cancer risk, but no studies have investigated this association among women in developing countries, and very few studies have further investigated this association according to menopausal status.
A population-based case-control study in Mexico with 1,000 incident breast cancer cases aged 35-69 years, enrolled shortly after diagnosis (0-6 days) and frequency-matched to 1,074 controls on age, region, and health care system, was used to assess the association between serum 25-hydroxyvitamin D [25(OH)D] levels with overall, pre- and postmenopausal breast cancer risk. 25(OH)D concentration was measured on a random sub-sample of women (573 cases and 639 matched controls) using a liquid chromatography/tandem mass spectrometry method. Odds ratios (ORs) and 95 % confidence intervals (CIs) were estimated from multivariable conditional logistic regression models.
Serum 25(OH)D concentration (per 10 ng/mL increase) showed a strong inverse association with risk of breast cancer among all (p(trend) = 0.001), pre- (p(trend) = 0.006) and postmenopausal women (p(trend) = 0.0001). Compared with a predefined lower concentration of 25(OH)D (<20 ng/mL), higher levels (>30 ng/mL) were associated with lower overall (OR = 0.53, 95 % CI: 0.28-1.00; p(trend) = 0.002), pre- (OR = 0.60, 95 % CI: 0.16-2.17; p(trend) = 0.07) and postmenopausal (OR = 0.37, 95 % CI: 0.16-0.82; p(trend) = 0.004) breast cancer risk.
The results of this large population-based case-control study indicate an inverse association between circulating vitamin D levels and breast cancer risk among pre- and postmenopausal Mexican women.
Cancer Causes and Control 05/2012; 23(7):1149-62. · 2.88 Impact Factor
ABSTRACT: ω-3 polyunsaturated fatty acids (PUFA) could play a protective role on the risk of breast cancer; however, little is known about this relation among Mexican women. We evaluated the association between ω-3 and ω-6 PUFA intake and breast cancer risk by obesity status in Mexican women.
A population-based case-control study was conducted in Mexico, including 1,000 incident breast cancer cases and 1,074 controls matched to cases by age, health care system, and region. Women provided information on health and diet by in-person interview. Body mass index (BMI) measures were used to define overall obesity. Obesity status was categorized as normal weight (18.5 < BMI < 25), overweight (25 ≤ BMI < 30), and obese (BMI ≥ 30). A conditional logistic regression model was used to assess the association between PUFA and breast cancer risk.
Overall, there was no significant association between ω-3 PUFA intake and breast cancer risk (P = 0.31). An increased risk of breast cancer was associated with increasing ω-6 PUFA intake in premenopausal women [OR = 1.92, 95% confidence interval (CI) = 1.13-3.26; P = 0.04]. A decreased risk of breast cancer was significantly associated with increasing ω-3 PUFA intake in obese women (OR = 0.58, 95% CI = 0.39-0.87; P = 0.008) but not in normal weight nor in overweight women (P(heterogeneity) = 0.017).
Obesity status may affect the association between ω-3 PUFA intake and breast cancer risk. The underlying mechanisms may be related to decreased inflammation and improved adipokin and estrogen levels induced by ω-3 PUFA in adipose tissue in obese women. Impact: Increased intake of ω-3 PUFA should be recommended among Mexican women in particular in obese women.
Cancer Epidemiology Biomarkers & Prevention 12/2011; 21(2):319-26. · 4.12 Impact Factor
ABSTRACT: Many studies have analyzed the effect of behavioral risk factors such as common lifestyle patterns on the risk of disease. The aim of this study was to assess the effect of a healthy lifestyle index on the risk of breast cancer.
A population-based case-control study was conducted in Mexico from 2004 to 2007. One thousand incident cases and 1,074 controls, matched to cases by 5-year age category, region, and health institution, participated in the study. A healthy lifestyle index was developed by means of principal components by using dietary pattern, physical activity, alcohol consumption, and tobacco smoking. A conditional logistic regression model was used to assess this association.
The healthy lifestyle index was defined as the combined effect of moderate and/or vigorous-intensity physical activity, low consumption of fat, processed foods, refined cereals, complex sugars, and the avoidance of tobacco smoking and alcohol consumption. Results showed a protective effect on both pre- (OR = 0.50, 95% CI: 0.29-0.84) and postmenopausal women (OR = O.20, 95% CI: 0.11-0.37) when highest versus lowest index quintiles were compared.
Healthy lifestyle was associated with a reduction in the odds of having breast cancer. Primary prevention of this disease should be promoted in an integrated manner. Effective strategies need to be identified to engage women in healthy lifestyles.
This study is the first to assess a healthy lifestyle index in relation to the risk of breast cancer.
Cancer Epidemiology Biomarkers & Prevention 02/2011; 20(5):912-22. · 4.12 Impact Factor
ABSTRACT: The importance of recruiting and retaining study participants from minority groups is well recognized; however, there are no established rules for recruitment as its success depends on the setting and population.
To describe and analyze recruitment strategies, ethical considerations, and recruitment outcomes from a study to evaluate the efficacy the Human Papilloma Virus vaccine in young men who have sex with men (MSM).
The recruitment settings were university and community sites in the state of Morelos, Mexico. Eligibility requirement were men between 18 and 23 years old, who were free of anal-genital lesions as confirmed by clinical exploration, HIV negative, with no history of sexual relations with female partners and with fewer than five male lifetime sexual partners. Recruitment goals were 25 study participants in a four and a half month period. In addition to traditional recruitment strategies (flyers and media advertising, specific training of the recruitment team and adequate choice of recruitment sites)-engagement of local leaders in the MSM community formed a crucial part of the strategy. Special consideration was given to confidentiality and respect for study participants and a Bill of Participant Rights was developed as an explicit commitment to respect and acceptance.
In total 723 MSM were initially contacted, 243 filled out the recruitment questionnaire, of which 151 met the criteria to be invited to the clinical examination. After clinical examination and interviews with the recruitment team, 131 fulfilled the inclusion criteria, of whom 73 were enrolled in the study - nearly triple the recruitment goal. Among the initial recruitment strategies (application of the screening questionnaire) attending meetings with MSM activist organizations was the most successful (326), followed by recruitment at bars and dance clubs (107).
The recruitment strategies should be formally evaluated for their effectiveness to identify those which are most successful. In addition, future studies should consider the evaluation of study participants' perceptions of the recruitment strategies.
Recruiting MSM in a developing country such as Mexico presented multiple challenges. We recommend that future studies actively engage the local MSM community and pay special attention to designing recruitment strategies that guarantee the confidentiality of and respect for participants.
Clinical Trials 08/2009; 6(4):365-72. · 1.92 Impact Factor