A prospective study of selenium status and breast cancer risk

Abstract

Low dietary intake of selenium has been proposed as a risk factor for breast cancer. To address this hypothesis, we collected toenail clippings from 62,641 women in the Nurses' Health Study cohort who were free from cancer (other than nonmelanoma skin cancer) in 1982 and 1983. The selenium concentration in nails has been shown to reflect dietary intake of selenium. During 53 months of follow-up, 434 cases of breast cancer were diagnosed among women who had submitted a set of toenail clippings, and we matched one control free from breast and other cancers to each case. The mean selenium level in toenails in the cases (0.823 microgram/g; SD, 0.197) was almost identical to that of the controls (0.821 microgram/g; SD, 0.174). After controlling for known breast cancer risk factors, the relative risk for women in the highest quintile of selenium as compared with the lowest quintile was 1.10 (95% confidence interval, 0.70 to 1.72) and there was no trend across quintiles. Results were similar for both premenopausal and postmenopausal women. Although these data do not exclude a possible influence of selenium intake before adulthood on subsequent risk of breast cancer, selenium intake later in life is not likely to be an important factor in the etiology of breast cancer.

Selenium in Breast Cancer

“…However, a low dietary intake cannot be blamed for low serum concentrations in all patients with breast cancer, nor can the negative findings in some studies be assumed to be spurious [12, 13, 14, 18]. Serum selenium levels did not vary with age in healthy women or women with chronic non-tumoral disease; however, in women with breast cancer we noted that the concentration was lowest in women aged 41–60 years.…”

“…The notion that dietary selenium deficiency led to lower serum levels of this trace element has been so strongly defended that cancer prevention programs have been based on dietary supplementation with this element [28]. In a prospective study by Hunter et al [18]no association between toenail selenium and the risk of breast cancer was observed during a 4-year follow-up. Several prospective investigations have also failed to detect any association between serum or toenail selenium and breast cancer [29].…”

“…However, Hunter et al [18]reviewed another five studies in search of a correlation between selenium levels in the blood and nails and the risk of breast cancer, but no statistically significant correlations were noted.…”

Selenium and breast cancer risk: A prospective nested case–control study on serum selenium levels, smoking habits and overweight

“…2,5,[8][9][10][11] In the 1990s several studies were performed regarding Se and breast cancer risk but they showed inconclusive results, with some reporting an inverse relationship and some not finding any association. [12][13][14][15][16][17][18] A review of these studies in 2007 showed no overall association with the risk of breast cancer. 1 However, expecting a rather modest effect, many of these studies might have had too few cases to get statistical power, the largest one including 434 cases.…”

“…1 However, expecting a rather modest effect, many of these studies might have had too few cases to get statistical power, the largest one including 434 cases. 17 Other previous limitations are that in many studies selenium was measured after the development of breast cancer, a fact that makes it difficult to exclude that the selenium status is affected by the disease or its treatment. 19,20 A stronger design would be prospective studies to avoid this potential bias that breast cancer affects the Se levels.…”