Selenium associated with a lower risk of bladder cancer

24 Sep 2010

Scientists in Spain have found that adding a can of tuna or other fish to our shopping lists could help protect us against bladder cancer.

Worldwide, bladder cancer is one of the most common types of cancer, with an estimated 356,600 new cases of the disease diagnosed each year. Highest incidences are in Spain and Italy and it is the seventh most common cancer in the UK.

Dr Nuria Malats and her team at the Madrid-based Spanish National Cancer Research Center, have shown that, particularly in women, high levels of the trace mineral, selenium, is associated with a lower risk of bladder cancer.

The work, part-funded by the Worldwide Cancer Research (formerly AICR), examined the levels of selenium in blood serum and toe nail cuttings.

The results now published in the journal: 'Cancer, Epidemiology, Biomarkers and Prevention' show that a high selenium intake is associated with lower rates of bladder cancer, particularly among women, which may be due to differences in the way the genders accumulate and excrete selenium.

Regarded as an antioxidant, Selenium has for some time been reported to have a protective effect against several cancer types, including lung, but, until now, its link to bladder cancer was uncertain.

Dietary selenium comes from nuts, cereals, meat, fish, and eggs. Depending on the soil in which they are grown, Brazil nuts can be the richest ordinary dietary source. High levels are also found in kidney, tuna, crab, and lobster.

There are several risk factors already linked to bladder cancer, the biggest being smoking, exposure to environmental tobacco smoke during childhood, age and occupational exposure to certain chemicals, particularly in countries with less-regulated industrial processes.

Dr Malats' meta-analysis considered the combined data from seven studies and 1910 bladder cancer cases before concluding that, the higher the concentration of selenium in our bodies, the lower the risk of bladder cancer.

However she cautioned that doctors should hold off before they start prescribing selenium supplements for bladder cancer patients.

“Although these findings suggest a protective effect of selenium for bladder cancer risk, additional large studies would be required to support these findings,” she explained.

AICR's scientific spokesman Dr Mark Matfield said: “Researchers have been struggling for years to pin down the protective effect of selenium against cancer – which types, how strong it is and how it works. This meta-analysis adds a new element to the field, with evidence that it may protect against bladder cancer, at least in women.”

Source: Worldwide Cancer Research

Article: Selenium and Bladder Cancer Risk: a Meta-analysis
André F.S. Amaral, Kenneth P. Cantor, Debra T. Silverman and Núria Malats
'Cancer, Epidemiology, Biomarkers and Prevention'