Somdat Mahabir

Birthplace, Years of Residence in the United States, and Obesity Among Mexican-American Adults

Objective: To evaluate the association between birthplace (Mexico or U.S.) and obesity in men and women and to analyze the relationship between duration of U.S. residency and prevalence of obesity in Mexican immigrants.

Relationship Between Obesity and Pathologic Response to Neoadjuvant Chemotherapy Among Women With Operable Breast Cancer

PURPOSE To understand the mechanism through which obesity in breast cancer patients is associated with poorer outcome, we evaluated body mass index (BMI) and response to neoadjuvant chemotherapy (NC) in women with operable breast cancer. PATIENTS AND METHODS From May 1990 to July 2004, 1,169 patients were diagnosed with invasive breast cancer at M. D. Anderson Cancer Center and received NC before surgery. Patients were categorized as obese (BMI >or= 30 kg/m(2)), overweight (BMI of 25 to < 30 kg/m(2)), or normal/underweight (BMI < 25 kg/m(2)). Logistic regression was used to examine associations between BMI and pathologic complete response (pCR). Breast cancer-specific, progression-free, and overall survival times were examined using the Kaplan-Meier method and Cox proportional hazards regression analysis. All statistical tests were two-sided. RESULTS Median age was 50 years; 30% of patients were obese, 32% were overweight, and 38% were normal or underweight. In multivariate analysis, there was no significant difference in pCR for obese compared with normal weight patients (odds ratio [OR] = 0.78; 95% CI, 0.49 to 1.26). Overweight and the combination of overweight and obese patients were significantly less likely to have a pCR (OR = 0.59; 95% CI, 0.37 to 0.95; and OR = 0.67; 95% CI, 0.45 to 0.99, respectively). Obese patients were more likely to have hormone-negative tumors (P < .01), stage III tumors (P < .01), and worse overall survival (P = .006) at a median follow-up time of 4.1 years. CONCLUSION Higher BMI was associated with worse pCR to NC. In addition, its association with worse overall survival suggests that greater attention should be focused on this risk factor to optimize the care of breast cancer patients.

Usefulness of body mass index as a sufficient adiposity measurement for sex hormone concentration associations in postmenopausal women.

Background: Both obesity and sex hormones are known risk factors for postmenopausal breast cancer. Although adiposity and sex hormones have been studied in the past, previous reports in postmenopausal women have not been conducted under carefully controlled dietary conditions. In this study, we investigated the usefulness of body mass index (BMI) as a sufficient adiposity measurement to assess associations with sex hormone levels. Methods: This study was conducted as a cross-sectional analysis within the control segment (0 g alcohol group) of a randomized, crossover design, in which 51 postmenopausal women consumed 0 (control), 15 (one drink), and 30 (two drinks) g alcohol (ethanol)/d for 8 weeks each as part of a controlled diet. Dual-energy X-ray absorptiometry scans were administered to the women during the control (0 g alcohol) segment, and a blood sample was drawn at the end of that diet period for hormone analysis. Results: In multivariate analysis (adjusted for age, race, family history of breast cancer, parity, and menarche <12 years), women who were overweight or obese had significantly higher serum concentrations of estradiol, bioavailable estradiol, estrone, and estrone sulfate and lower sex hormone-binding globulin than normal weight women (all P < 0.05). In models adjusted for BMI and the covariates above, none of the dual-energy X-ray absorptiometry adiposity measures added further information (all P > 0.10) for these five analytes beyond that of BMI alone. Conclusions: In this population of postmenopausal women, under carefully controlled dietary conditions, we confirmed previous findings that higher levels of adiposity were associated with higher concentrations of estrogens and lower sex hormone-binding globulin, and we found that the use of the epidemiology-friendly BMI seems sufficient to assess associations with these hormone levels. (Cancer Epidemiol Biomarkers Prev 2006;15(12):2502–7)

Energy balance and carcinogenesis: underlying pathways and targets for intervention.

The prevalence of obesity, an established epidemiologic risk factor for many cancers, has risen steadily for the past several decades in the U.S. Particularly alarming are the increasing rates of obesity among children, portending continuing increases in the rates of obesity and obesity-related cancers for many years to come. Unfortunately, the mechanisms underlying the association between obesity and cancer are not well understood. In particular, the effects and mechanistic targets of interventions that modulate energy balance, such as reduced calorie diets and physical activity, on the carcinogenesis process have not been well characterized. The purpose of this review is to provide a strong foundation for future mechanistic-based research in this area by describing key animal and human studies of energy balance modulations involving diet, exercise, or pharmaceutical agents and by focusing on the interrelated pathways affected by alterations in energy balance. Particular attention in this review is placed on the components of the insulin/IGF-1/Akt pathway, which has emerged as a predominant target for disrupting the obesity-cancer link. Also discussed is the promise of global approaches, including genomics, proteomics, and metabolomics, for the elucidation of energy balance-responsive pathways. The ultimate goal of this work is to provide the missing mechanistic information necessary to identify targets for the prevention and control of cancers related to or caused by excess body weight.

Calorie intake misreporting by diet record and food frequency questionnaire compared to doubly labeled water among postmenopausal women

Objective:We assessed the extent of energy misreporting from the use of a self-administered 7-day diet record (7-DDR) and a widely used food frequency questionnaire (FFQ) compared to total energy expenditure from doubly labeled water (DLW) in a group of postmenopausal women.Design:At baseline, 65 healthy postmenopausal women were instructed to fill out the National Cancer Institutes (NCI) FFQ and a 7-DDR. Average total energy expenditure using the DLW method was also performed at baseline.Results:On average, the women underestimated total energy intake compared to total energy expenditure assessed from DLW by 37% on the 7-DDR and 42% on the FFQ.Conclusions:These findings suggest that the interpretation of findings from the 7-DDR- and FFQ-based energy-disease association studies in postmenopausal women needs further evaluation.Sponsorship:This research was supported (in part) by the Intramural Program of the NIH (National Cancer Institute).

Dietary zinc, copper and selenium, and risk of lung cancer

Zinc, copper and selenium are important cofactors for several enzymes that play a role in maintaining DNA integrity. However, limited epidemiologic research on these dietary trace metals and lung cancer risk is available. In an ongoing study of 1,676 incident lung cancer cases and 1,676 matched healthy controls, we studied the associations between dietary zinc, copper and selenium and lung cancer risk. Using multiple logistic regression analysis, the odds ratios (OR) and 95% confidence intervals (CI) of lung cancer for all subjects by increasing quartiles of dietary zinc intake were 1.0, 0.80 (0.65–0.99), 0.64 (0.51–0.81), 0.57 (0.42–0.75), respectively (p trend = 0.0004); similar results were found for men. For dietary copper, the ORs and 95% CI for all subjects were 1.0, 0.59 (0.49–0.73), 0.51 (0.41–0.64), 0.34 (0.26–0.45), respectively (p trend < 0.0001); similar reductions in risk and trend were observed by gender. Dietary selenium intake was not associated with risk, except for a significant inverse trend (p = 0.04) in men. Protective trends (p < 0.05) against lung cancer with increased dietary zinc intake were also found for all ages, BMI > 25, current smokers, pack‐years ≤30, light drinkers and participants without emphysema. Increased dietary copper intake was associated with protective trends (p < 0.05) across all ages, BMI, smoking and vitamin/mineral supplement categories, pack‐years ≤30 and 30.1–51.75 and participants without emphysema. Our results suggest that dietary zinc and copper intakes are associated with reduced risk of lung cancer. Given the known limitations of case–control studies, these findings must be interpreted with caution and warrant further investigation.

Measures of adiposity and body fat distribution in relation to serum folate levels in postmenopausal women in a feeding study

Objective:To assess the associations between serum folate concentration and measures of adiposity in postmenopausal women.Design:This study was conducted as a cross-sectional analysis within the control segment of a randomized, crossover trial in which postmenopausal women (n=51) consumed 0 g (control), 15 g (one drink) and 30 g (two drinks) alcohol (ethanol)/day for 8 weeks as part of a controlled diet. Subjects in one treatment arm were crossed-over to another arm after a 2- to 5-week washout period. Body mass index (BMI) was measured, and dual energy X-ray absorptiometry (DEXA) scan administered to the women during the control (0 g alcohol) treatment, and a blood sample from this group was collected at baseline and week 8 of each diet period and analyzed for folate, B12, homocysteine and methylmalonic acid.Setting:This study was conducted at the Beltsville Human Nutrition Research Center, MD, USA.Results:In multivariate analysis, women who were overweight had a 12% lower, and obese women had a 22% lower serum folate concentrations compared to normal weight women (P-trend=0.02). Vitamin B12 also decreased with increasing BMI (P-trend=0.08). Increased BMI, percent body fat, and absolute amounts of central and peripheral fat were all significantly associated with decreased serum folate, but were unrelated to serum B12, homocysteine or methylmalonic acid.Conclusions:Our data show that adiposity is associated with lower serum folate levels in postmenopausal women. With obesity at epidemic proportions, these data, if confirmed by prospective or randomized controlled studies, have important public health implications.

Dietary Boron and Hormone Replacement Therapy as Risk Factors for Lung Cancer in Women

Hormone replacement therapy (HRT) may reduce lung cancer risk. Dietary boron may have actions similar to those of HRT; however, no previous study has reported the associations between dietary boron intake and lung cancer risk or the joint effects of boron intake and HRT use on lung cancer risk. The authors examined the associations between boron intake and the joint effects of boron intake and HRT on lung cancer risk in women. In an ongoing case-control study in Houston, Texas (July 1995 through April 2005, end date for this analysis), 763 women were diagnosed with lung cancer, and 838 were matched healthy controls with data on both diet and HRT. Multiple logistic regression analyses were conducted to assess the associations between dietary boron and HRT with lung cancer risk. After adjustment for potential confounders, the odds ratios for lung cancer with decreasing quartiles of dietary boron intake were 1.0, 1.39 (95% confidence interval (CI): 1.02, 1.90), 1.64 (95% CI: 1.20, 2.24), and 1.95 (95% CI: 1.42, 2.68) mg/day, respectively, for all women (p(trend) < 0.0001). In joint-effects analyses, compared with women with high dietary boron intake who used HRT, the odds ratio for lung cancer for low dietary boron intake and no HRT use was 2.07 (95% CI: 1.53, 2.81). Boron intake was inversely associated with lung cancer in women, whereas women who consumed low boron and did not use HRT were at substantial increased odds.

Physical activity and renal cell cancer risk in a cohort of male smokers.

Few studies have examined exercise in relation to risk of renal cell cancer. We examined the association between leisure‐time and occupational physical activity and renal cell cancer in a cohort of 29,133 male smokers 50–69 years of age in the Alpha‐Tocopherol, Beta‐Carotene (ATBC) Cancer Prevention Study. Physical activity was assessed at baseline using a self‐administered questionnaire that inquired about usual level of physical activity during leisure‐time and at work during the past year. Cox proportional hazards modeling was used to adjust simultaneously for known or suspected risk factors for renal cell cancer. During 12 years (354,407 person‐years) of follow‐up, 210 incident cases of renal cell cancer were identified. In age‐adjusted analysis, the RRs of renal cell cancer in increasing categories of leisure‐time physical activity (light, moderate and heavy) were 1.0, 0.89 (95% CI = 0.67–1.17) and 0.38 (95% CI = 0.15–0.94), respectively (p‐value for trend = 0.06). After adjustment for body mass index, energy intake, smoking, hypertension, education and fruit and vegetable intake, the multivariate RRs of renal cell cancer in increasing categories of leisure‐time physical activity (light, moderate and heavy), were 1.0, 0.89 (95% CI = 0.66–1.19), and 0.46 (95% CI = 0.18–1.13) (p‐value for trend = 0.12). Occupational physical activity was unrelated to renal cell cancer risk. These data suggest that recreational physical activity may play a role in the prevention of renal cell cancer in men.

Dietary magnesium and DNA repair capacity as risk factors for lung cancer

Magnesium (Mg) is required for maintenance of genomic stability; however, data on the relationship between dietary Mg intake and lung cancer are lacking. In an ongoing lung cancer case-control study, we identified 1139 cases and 1210 matched healthy controls with data on both diet and DNA repair capacity (DRC). Dietary intake was assessed using a modified Block-NCI food frequency questionnaire and DRC was measured using the host-cell reactivation assay to assess repair in lymphocyte cultures. After adjustment for potential confounding factors including DRC, the odds ratios (ORs) and 95% confidence intervals (CIs) for lung cancer with increasing quartiles of dietary Mg intake were 1.0, 0.83 (0.66-1.05), 0.64 (0.50-0.83) and 0.47 (0.36-0.61), respectively, for all subjects (P-trend < 0.0001). Similar results were observed by histology and clinical stage of lung cancer. Low dietary Mg intake was associated with poorer DRC and increased risk of lung cancer. In joint effects analyses, compared with those with high dietary Mg intake and proficient DRC, the OR (95% CI) for lung cancer in the presence of both low dietary Mg and suboptimal DRC was 2.36 (1.83-3.04). Similar results were observed for men and women. The effects were more pronounced among older subjects (>60 years), current or heavier smokers, drinkers, those with a family history of cancer in first-degree relatives, small cell lung cancer and late-stage disease. These intriguing results need to be confirmed in prospective studies.