Written by Gabriele Dennert and the CAM-Cancer Consortium.
Updated October 20, 2013

Selenium – during cancer treatment

Does it work?

This summary is currently (April 2016) being updated, the version published here was last updated in October 2013. 

Treating cancer and preventing recurrence

Asfour et al. (2007) investigated the use of high doses of sodium selenite in the treatment of non-Hodgkin lymphoma. 14 Fifty participants with aggressive lymphoma were randomised into the intervention group receiving CHOP-28 plus selenium and a control group, which received CHOP-28 alone (CHOP: cyclophosphamide, vincristine, adriamycin; cycle length: 28 days). Sodium selenite (200µg/kg/day = about 14 mg/day for a 70 kg adult) was administered orally on each day of the first course of chemotherapy. More participants in the selenium group reached complete remission compared to the control group (60% vs. 40%). The overall survival rate after two years was 72% in the control group and 80% in the selenium group (no statistically significant difference). Generalisability of these results to other patients is limited as the report lacks information about the histological type of the lymphomas and the distribution of risk factors (for example, the International Prognostic Index) between both groups. Both parameters strongly predict the response to CHOP chemotherapy. Also it should be mentioned that CHOP-28 is not the standard therapy for aggressive lymphoma in high-income countries.

Karp et al. (2013) conducted a double-blind, placebo-controlled randomised trial for the prevention of second primary tumours (SPT) in persons with resected stage I non-small-cell lung cancer. 15 The verum group took 200µg of selenium yeast daily. The trial was terminated early after an interim analysis of 1522 patients showed no benefit of selenium over placebo with regard to the incidence of SPT and five-year progression-free survival. At the five-year mark, 28% in the selenium group and 22% in the placebo group had experienced cancer progression.

To summarise, there is insufficient evidence to support the use of selenium for treating cancer or preventing recurrence.

Alleviating the adverse effects of conventional therapy

Systematic review

A Cochrane review has assessed the use of selenium mono-supplements for the prevention or alleviation of adverse effects of conventional cancer therapy. 16

Two randomised clinical trials were identified, which used sodium selenite for the treatment of lymphedema and the prevention of erysipelas in affected limbs after cancer surgery. 17,18 Both trials were considered to be at high risk of bias, and the authors of the review concluded that it was unclear whether the reported results in these trials reflected a clinically relevant reduction in postoperative lymphedema or erysipelas infection in the selenium group. Generalisation to other cancer patients was also considered questionable.

Clinical trials

Two randomised trials have investigated the efficacy of sodium selenite for the treatment of selenium deficiency in cancer patients receiving radiotherapy. All study participants had subclinical selenium deficiency (i.e., whole-blood concentration below 85µg/l) and received radiotherapy for gynaecological cancers (n=81) 19 or head and neck cancers (n=39) with or without concomitant selenium supplementation. 20,21 Both trials also reported on radiotherapy-associated side effects as secondary outcomes. A pooled analysis of both trials found that blood selenium levels were normalised by selenium supplementation. 22 For secondary outcomes, the gynaecological trial found an overall decreased risk of diarrhoea (grade 2 or higher according to the National Cancer Institute Common Toxicity Criteria version 2) in the selenium group. No differences in survival rates were seen. While the rate of stomatitis was higher in the selenium group (intervention vs. no intervention group: 36.4% vs. 23.5%.), participants that received selenium complained less about loss of taste (22.7% vs. 47.1%), and dysphagia (22.7% vs. 35.3%) and with an almost identical frequency about dry mouth (22.7% vs. 23.5%); none of these differences were statistically significant.

Hu et al. (1997) measured biomarkers of cisplatin toxicity using a randomised crossover design with 41 participants. 23 A dose of 4000µg/day seleno-kappacarrageenan was administered orally over eight days in the intervention groups (organic selenium compound: carrageenan is a polysaccharide). Investigators reported a higher white blood count (WBC) at day 14 after chemotherapy and lower levels of cisplatin toxicity biomarkers in urine with selenium, suggesting reduced cisplatin-associated bone marrow suppression and nephrotoxicity. Red blood and platelet count did not differ, but fewer blood transfusions and doses of G-CSF (growth factor for leucocytes) were administered during chemotherapy cycles with selenium. Although the results of this study are interesting, the clinical relevance of the results is disputable. For WBC, means were compared in the presence of concomitant G-CSF application. G-CSF can lead to an excessively high WBC and the comparison of means is sensitive towards extreme values. Differences in urine biomarkers were found 24 hours and 48 hours after cisplatin application, but not 72 hours after application, and blood biomarkers and the laboratory reference limits were not reported. Cisplatin nephrotoxicity has an acute phase (beginning after two to three days) and a delayed phase (two weeks after application) and it seems questionable whether the reported biomarker adequately reflects the occurrence of this adverse effect.

To summarise, one trial reported a clinical benefit (less severe diarrhoea) with selenium supplementation for women during radiotherapy of the pelvic region. Other clinical trials and one systematic review do not support the regular use of selenium supplements during cancer therapy.

Citation Gabriele Dennert, CAM-Cancer Consortium. Selenium – during cancer treatment [online document]. http://ws.cam-cancer.org/The-Summaries/Dietary-approaches/Selenium-during-cancer-treatment. October 20, 2013.


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