[Potential of selenium in gynecologic oncology]

An Assessment of Serum Selenium Concentration in Women with Ovarian Cancer

BACKGROUND

Available studies on the effect of serum selenium levels on the risk of malignancies show some conflicting results. In this study, we investigated the correlation between serum selenium levels and ovarian cancer occurrence.

METHODS

314 women (157 diseased patients and 157 healthy ones) matched in terms of age and BMI were included in the study. The measurements of selenium in the collected blood samples were performed using an ICP mass spectrometer. Univariable and multivariable analyzes were performed to determine the relationship between the factors under the study and the occurrence of ovarian cancer.

RESULTS

The mean concentration of selenium was lower among diseased ones than among controls (53.31 μg/L vs. 78.99 μg/L). A decrease in selenium concentration was noticed with the advancement of ovarian cancer. In univariable and multivariable analyzes, a clear relationship between low selenium concentration and the occurrence of ovarian cancer was found (35.3 (95% CI: 11.2-111; p < 0.001) and 45.8 (95% CI: 12.8-164; p < 0.001)).

CONCLUSION

The studied patients with ovarian cancer are characterized by statistically significant lower serum selenium levels than patients from the control group. Among the study group, a decrease in selenium concentration was observed with an increase in the FIGO stage. The determination of the role of selenium as a prophylactic factor in ovarian cancer requires further prospective studies.

Selenium or no selenium--that is the question in tumor patients: a new controversy

The essential trace element selenium, which is a crucial cofactor in the most important endogenous antioxidative systems of the human body, is attracting more attention from both laypersons and expert groups. The interest of oncologists mainly focuses on the following clinical aspects: protection of normal tissues, sensitizing in malignant tumors, antiedematous effect, prognostic impact of selenium, and effects in primary and secondary cancer prevention. Selenium is a constituent of the small group of selenocysteine-containing selenoproteins and elicits important structural and enzymatic functions. Selenium deficiency has been linked to increased infection risk and adverse mood states. It has been shown to possess cancer-preventive and cytoprotective activities in both animal models and humans. It is well established that it has a key role in redox regulation and antioxidant function, and hence in membrane integrity, energy metabolism, and protection against DNA damage. Recent clinical trials have shown the importance of selenium in clinical oncology. In 2009, a significant benefit of sodium selenite supplementation-with no protection of tumor cells, which is often suspected by oncologists- was shown in a prospective randomized trial in gynecologic cancer patients undergoing radiation therapy. More recently, concerns arose from 2 large clinical prevention trials (NPC, SELECT) that selenium may increase the risk of developing type 2 diabetes. Despite obvious flaws in both studies and good counterarguments, controversy remains on the possible advantages and risks of selenium in cancer prevention. However, in the light of the recent clinical trials the potential benefits of selenium supplementation in tumor patients are becoming obvious, even though further research is needed.

Multicenter, phase 3 trial comparing selenium supplementation with observation in gynecologic radiation oncology

PURPOSE

We assessed whether adjuvant supplementation with selenium improves the selenium status and reduces side effects of patients treated by radiotherapy (RT) for cervical and uterine cancer.

METHODS AND MATERIALS

Whole-blood selenium concentrations were measured in patients with cervical cancer (n = 11) and uterine cancer (n = 70) after surgical treatment, during RT, at the end of RT, and 6 weeks after RT. Patients with initial selenium concentrations of less than 84μg/L were randomized before RT either to receive 500 μg of selenium (in the form of sodium selenite [selenase, biosyn Arzneimittel GmbH, Fellbach, Germany]) by mouth on the days of RT and 300 μg of selenium on the days without RT or to receive no supplement during RT. The primary endpoint of this multicenter Phase 3 study was to assess the efficiency of selenium supplementation during RT; the secondary endpoint was to decrease radiation-induced diarrhea and other RT-dependent side effects.

RESULTS

A total of 81 patients were randomized. We enrolled 39 in the selenium group (SG) and 42 in the control group (CG). Selenium levels did not differ between the SG and CG upon study initiation but were significantly higher in the SG at the end of RT. The actuarial incidence of diarrhea of Grade 2 or higher according to Common Toxicity Criteria (version 2) in the SG was 20.5% compared with 44.5% in the CG (p = 0.04). Other blood parameters, Eastern Cooperative Oncology Group performance status, and self-reported quality of life were not different between the groups.

CONCLUSIONS

Selenium supplementation during RT is effective in improving blood selenium status in selenium-deficient cervical and uterine cancer patients and reduces the number of episodes and severity of RT-induced diarrhea.

Whole blood selenium levels (WBSL) in patients with prostate cancer (PC), benign prostatic hyperplasia (BPH) and healthy male inhabitants (HMI) and prostatic tissue selenium levels (PTSL) in patients with PC and BPH

BACKGROUND

The aim of this exploratory study was to evaluate whether significant differences exist between whole blood selenium levels (WBSL) in patients with prostate cancer (PC), benign prostatic hyperplasia (BPH), healthy male inhabitants (HMI) in northern Bavaria and the normal value. Furthermore, we investigated whether differences exist between prostatic tissue selenium levels (PTSL) in patients with PC, BPH and the benign tissue surrounding the PC.

MATERIAL AND METHODS

We prospectively evaluated WBSL in 24 patients with PC, 21 patients with BPH, and 21 HMI. Measurements of PTSL were performed in 17 patients with PC and 22 patients with BPH. In 9 cases with PC, measurements were also done in the benign tissue surrounding the carcinoma. Measurements were performed using automated graphite furnace atomic absorption spectrophotometry.

RESULTS

In patients with PC, there is a significantly lower WBSL in comparison to HMI (p=0.04). There is no significant difference in WBSL between BPH-patients and HMI (p=0.13) and between PC- and BPH-patients (p=0.67). In all patients and the HMI, there is a significantly lower WBSL in comparison to the recommended normal value of 85-162 microg/l (p<0.01). There is no significant difference in PTSL between PC and BPH (p=0.49), and between PC and the tissue compartment surrounding the PC (p=0.56). PTSL seemed to be reduced in the compartment surrounding the PC in comparison to BPH (p=0.03). In PC-patients, there is no significant correlation between WBSL and prostate specific antigen (PSA) (? = -0.20; p=0.36), Gleason score (? = 0.32, p=0.13), and T-stage (? = 0.22; p=0.23).

CONCLUSION

Since the WBSL measured in all men with PC and BPH, and in HMI participating in our study were significantly lower than the recommended normal range, our findings may support the recommendation of selenium supplementation.