Selenium in serum as a possible parameter for assessment of breast disease

A comparative study of selenium concentration and glutathione peroxidase activity in normal and breast cancer patients

OBJECTIVE

The present study was undertaken to compare plasma Se values and glutathione peroxidase (GPX) activity in normal and breast cancer patients.

DESIGN

In a case-control study, forty-five breast cancer patients and the same number of healthy women were randomly selected from their population. Se was measured in plasma by atomic absorption spectrophotometry and GPX activity in erythrocytes was measured using a standard spectrophotometric method.

RESULTS

Plasma Se concentration in healthy women and breast cancer patients was in the normal range, with no statistically significant difference observed between the two groups (138.40 (sd 40.36) microg/l v. 132.15 (sd 35.37) microg/l, respectively). Erythrocyte GPX activity was significantly (P<0.01) higher in breast cancer patients (24.81 (sd 11.66) U/g Hb) compared with healthy women (20.29 (sd 4.24) U/g Hb).

CONCLUSION

The present study indicated that Se deficiency was not a problem in the participants, and sufficient quantity of this element could increase GPX activity to have a protective effect against oxidative damage.

Selenium and cancer: some nutritional aspects

The level of selenium in cancer patients is lower than that in control subjects. However, low selenium levels in body fluids can be due to the malnutrition observed in these patients. There is evidence from epidemiologic studies that high dietary selenium intakes and high selenium status in people are associated with lower cancer mortality. However, contradictory information has been found in some prospective studies. The presence of other nutrients in selenium-rich foods can influence the role of the selenium in cancer etiology. Therefore, there are selenium antagonistic elements that inhibit the anticarcinogenic effects of selenium and other antioxidant micronutrients such as ascorbic acid, retinol, beta-carotene, alpha-tocopherol, and some other elements have a synergistic effect on the prevention of cancer.

Determination of selenium in blood serum of children with acute leukemia and effect of chemotherapy on serum selenium level

The concentration of selenium in serum was measured by the neutron activation method in three groups of children: 30 healthy children, 20 children with Acute Myeloblastic Leukemia (AML) and 40 with Acute Lymphoblastic Leukemia (ALL) (L1; n = 20, L2; n = 20). The samples were taken before and after induction chemotherapy. Age, sex, FAB, initial WBC, BUN, creatinine and urinary analysis did not show a significant change in the amount of selenium in serum. Selenium concentration in serum samples of ALL children before chemotherapy showed no significant differences as compared with that of normal individuals, but there were significant differences between children with AML and normal individuals (76.46 +/- 24.59 micrograms/L vs 102.38 +/- 19.25 micrograms/L, with p < 0.02). In conclusion, the question of whether these deficiencies are responsible for the disease or are the result of a secondary effect of the cancer remain to be answered. Immediately after induction chemotherapy, the selenium concentration in the serum of ALL children decreased significantly (80.14 +/- 15.48 micrograms/L vs 110.72 +/- 28.3 micrograms/L, p < 0.001), but this was not the case for AML children. These findings may be due to the difference in the drugs administered in induction chemotherapy of ALL and AML children.

Association between oxidative stress and changes of trace elements in patients with breast cancer

OBJECTIVES

To investigate the association between oxidative stress and certain trace elements in the blood of breast cancer patients.

DESIGN AND METHODS

Malondialdehyde (MDA) was measured in serum of patients with breast cancer (n = 35) and controls (n = 35) by high performance liquid chromatography. Trace elements were determined by atomic absorption spectrophotometry.

RESULTS

In the present study, significantly increased lipid peroxidation, measured as MDA, was demonstrated in the serum of breast cancer patients (p < 0.01). The concentrations of zinc and iron remained unaltered. However, the mean serum copper level in patients with breast cancer was significantly higher than the control group (p < 0.01). In addition, the mean serum selenium level in patients with stage III was significantly lower than the control group (p < 0.05). Moreover, a positive correlation was also observed between copper and MDA levels in the patient group but not in the control group.

CONCLUSION

In the present study, the presence of an association between oxidative stress and trace elements was observed in patients with breast cancer. We suggest that increased oxidative stress in patients with breast cancer may result from changes in the levels of certain trace elements.

Trace element correlations in the blood of Indian women with breast cancer

Fourteen minor (Na, K, P, Fe) and trace (Br, Co, Cr, Cs, Hg, Rb, Sb, Se, Sr, Zn) elements have been determined in pre- and postoperative blood samples of 10 breast-cancer-affected. Indian women and compared with controls. The study showed elevation of Cr, Hg, Fe, Rb, Sb, and Zn and lowering of Se, K, P, and Sr contents in the blood of cancer patients. Most elemental contents in pre- and postoperative stages remain unaltered except Br, Co, and Sb. Statistical significance of Fe, Se, Zn, and Hg levels has been tested by box plots. Lowering of Se in blood (-54.4%) is correlated with its enhancement in cancerous breast tissue (94.7%) of various clinical stages. Se/Zn and Se/Fe ratios are lowered in the blood of cancer patients, whereas Na/K ratio is only marginally enhanced. An attempt has been made to correlate Se levels with the dietary intake and breast cancer risk vis-a-vis American and Japanese women.

A case-control study on selenium, zinc, and copper in plasma and hair of subjects affected by breast and lung cancer

The purpose of our study was to investigate the relationship between plasma and hair levels of Se, Zn, and Cu, and cancer. We selected a total of 66 patients affected by either breast (38) or lung (28) cancer. They entered into the study at the onset of disease, and before any chemical or radiotherapy. Controls were randomly selected among healthy people and were matched for sex, age, smoking habits, and residence. In the group of breast cancer, a significant decrease in hair Se was found compared to controls (p < 0.01), whereas plasma Se was only slightly decreased. No difference between cases and controls was detected in both hair and plasma levels of Zn and Cu. Subjects who developed lung cancer were significantly lower in hair Zn (p < 0.05) and Cu (p < 0.01) than controls, whereas there was no difference with regard to Se. In addition, plasma Cu of these patients was increased as compared to controls.

Diet, serum markers and breast cancer mortality in China

This county-based correlation study examined associations of breast cancer mortality with dietary habits and certain serum biochemical markers, utilizing data collected from an ecological survey in 65 Chinese rural counties. Univariate correlation and multivariate regression analysis showed that consumption of animal foods, including eggs, fish and meat, was positively linked to county-wide mortality rates of breast cancer in Chinese women. No clear associations between breast cancer mortality rates and consumption of green vegetables, carrots and fruits were observed in this study. A modest inverse correlation between serum vitamin C levels and breast cancer mortality was observed, while selenium levels were positively related to the mortality rates. Positive correlations for serum ferritin and hemoglobin were found, in agreement with recent reports of an elevated cancer risk with increased body iron stores. Limitations of these ecological data preclude causal inferences, but the findings provide clues to breast cancer risk and protective factors in a low incidence area of the world.

Antioxidant micronutrients and breast cancer

We reviewed epidemiologic evidence on the relationship between four antioxidant micronutrients (vitamin A, vitamin C, vitamin E, and selenium) and breast cancer risk. Available data support a modest protective effect of vitamin A, although more studies are needed to examine further this association and to assess the relative contributions of preformed vitamin A (retinol) and carotenoids. In addition, the possibility that some other component of vitamin A-rich foods may account for this observed association should be explored. Data on the relationship between vitamins C and E and breast cancer risk are limited and inconsistent, and further information is necessary. A substantial body of evidence indicates a lack of any appreciable effect of selenium intake on breast cancer risk, at least within the range of human diets. Future observational studies should ideally be prospective in design, as prospective studies are less prone to selection and recall bias than are case-control studies, and should address methodologic issues such as confounding by other micronutrients and appropriate storage conditions of blood specimens. Although hypotheses relating micronutrient intake to risk of breast cancer should be tested in randomized trials, ethical and logistical constraints make these studies difficult to perform.

DNA pattern and dietary habits in patients with breast cancer

An association between dietary fat, micronutrients and breast cancer aetiology and prognosis has been found in studies of experimental animals and in epidemiological studies. The relationship between dietary habits and the nuclear DNA content of breast cancer cells was studied in 82 women aged 50-65 years. A dietary history interview was conducted within 4 months following surgery. Patients having tumours with euploid DNA pattern reported lower mean intake of saturated fatty acids (FA) in absolute terms, lower mean intake of total fat, saturated FA, and monounsaturated FA, in percentage of total energy intake (E%), a higher E% from protein, and a higher intake of vitamin D, and selenium per 10 MJ than did patients having tumours with aneuploid DNA pattern. In the stepwise logistic regression analysis, the multivariate odds ratios (OR) for having a tumour with aneuploid DNA pattern was 1.16 (95% confidence interval, 1.04-1.28) for each 1 g increase in intake of total fat (E%) and 0.95 (95% confidence interval, 0.92-0.99) for each mg increase in selenium intake per 10 MJ. When total fat was substituted with types of fat, the OR for having a tumour with aneuploid DNA pattern was 1.30 (95% confidence interval, 1.07-1.59) for each 1 g increase in intake of saturated FA (E%). These results suggest a correlation between a diet rich in fat and protein and the DNA content of breast cancer cells.

The effect of postoperative radiotherapy on leukocyte zinc, serum trace elements and nutritional status of breast cancer patients

Mononuclear (MNC) and polymorphonuclear cell (PMNC) zinc content was determined together with serum zinc, copper, selenium and iron concentrations in 24 operable breast cancer patients during and after postoperative radiotherapy. Anthropometric and biochemical indices of nutritional status were measured as background data. The measurements were carried out in the years 1987-1988. Nine patients used unconventional multivitamin or trace element preparations. A steady but statistically insignificant decrease in PMNC zinc was seen during treatment. No changes occurred in MNC zinc. Serum copper levels increased in five patients possibly due to tamoxifen treatment, but no other alterations occurred in serum trace element levels. Appetite was well maintained and nutritional status remained unaltered. Postoperative radiotherapy for breast carcinoma had thus no effect on either trace element or nutritional status. Patient-initiated alternative treatments did not significantly affect their trace element levels. This was probably due to small supplementation doses or irregular use of the preparations.