Investigations on the nutritional status of advanced breast cancer patients. The influence of long-term treatment with megestrol acetate or tamoxifen

The plasma level of retinol, vitamins A, C and α-tocopherol could reduce breast cancer risk? A meta-analysis and meta-regression

PURPOSE

Plasma antioxidants are supposed to be directly related to breast cancer risk. However, the results remain inconsistent. Herein, we carried this meta-analysis to comprehensively summarize the associations between plasma retinol, vitamins A, C and α-tocopherol and breast cancer risk.

METHODS

We searched PubMed, Embase and the Cochrane Databases (through September 24, 2014) and the reference lists of the retrieved articles in English with sufficient information to estimate relative risk or odds ratio and the 95% confidence intervals (CIs), or with mean serum/plasma level of vitamins and SD/SEM/p value in breast cancer and controls. Two reviewers independently extracted data using a standardized form, with any discrepancy adjudicated by the third reviewer.

RESULTS

Forty studies entered this meta-analysis. For the pooled OR, no significant association between plasma retinol and breast cancer was observed (p = 0.13). Significant association was observed between plasma α-tocopherol and breast cancer (pooled OR 0.42, 95% CI 0.25, 0.72, p = 0.00) in the subgroup with the median lowest level of 5.74-9.16 μmol/L. For the weighted mean difference (WMD), the plasma α-tocopherol and vitamin C level between breast cancer and controls were significantly different [WMD = -0.93 μmol/L (95% CI -1.26, -0.61, p = 0.00) and -2.51 μmol/L (95% CI -4.00, -1.02, p = 0.00), respectively]. No significant association between plasma retinol and vitamin A and breast cancer was observed.

CONCLUSIONS

Severe α-tocopherol deficiency could increase breast cancer risk. The association between plasma vitamin C and breast cancer was only significant in case-control studies. There was no significant association between other vitamins and breast cancer risk.

Plasma selenium and plasma and erythrocyte glutathione peroxidase activity increase with estrogen during the menstrual cycle

OBJECTIVE

This study was designed to determine the timing and magnitude of changes in selenium status in relation to the fluctuation of 17-beta-estradiol during the menstrual cycle and the effect of different phases of the menstrual cycle on dietary selenium intake.

METHODS

Plasma 17-beta-estradiol and plasma and erythrocyte selenium and glutathione peroxidase (GPx) activity were measured in fasting blood samples collected in the morning at four times over three phases of the menstrual cycle: early follicular (EF: days 1-3 menstruation), periovulatory (PO; E-1: 1 day before estrogen peak and E: during estrogen peak) and mid-luteal (ML: 7-9 days after ovulation) in healthy women (n = 14) aged 21 to 39 years and with regular menstrual cycles (26 to 30 days). The estrogen peak was confirmed by measurement of the luteinizing hormone surge. Dietary records (three-day) coincided with blood collection for each phase.

RESULTS

Plasma selenium and plasma and erythrocyte GPx activity were greatest during the periovulatory phase, coinciding with the estrogen peak. No differences were observed for erythrocyte selenium or dietary selenium throughout the cycle. A linear relationship existed between estradiol and plasma selenium (p < 0.0027), plasma GPx activity (p < 0.0001), and erythrocyte GPx activity (p < 0.0001).

CONCLUSIONS

These results indicate that blood selenium parameters fluctuate during the menstrual cycle such that the phase of the cycle should be considered when assessing selenium status.

A new method of food intake quantification: application to the care of cancer patients

Although it is commonly accepted that advanced cancer patients often suffer from malnutrition, there is little information available to quantify the extent of undernourishment and variations in food intake during the last weeks of life. To assess these factors, we developed a new method for measuring daily food intake, based on a self-descriptive record on which the patient chooses one of five different levels of food intake defined with a key word. This record was combined with a visual analogue scale and then administered to 100 healthy persons to assess if each key word can be attributed a numerical figure. Following this, the measurement method was applied to 75 cancer patients in the last weeks of life. The data confirmed and quantified the patients' undernutrition, and demonstrated a sharp and statistically significant increase in food intake when patients enter a palliative home care program. During the last 4 wk of life, the decrease in food intake became steady and irreversible.