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Toenail trace element levels and breast cancer: a prospective study
M Garland1, J S Morris, G A Colditz
1Department of Epidemiology, Harvard School of Public Health, Boston, MA.
American Journal of Epidemiology
|October 1, 1996
Summary
This study found no significant link between toenail levels of arsenic, copper, chromium, iron, or zinc and overall breast cancer risk in US women. Some evidence suggested a possible association with chromium in postmenopausal women, but not premenopausal women.
Area of Science:
- Epidemiology
- Nutritional Science
- Oncology
Background:
- Trace elements are essential for biological functions.
- Dietary intake and body burden of trace elements may influence cancer risk.
- Previous research on trace elements and breast cancer has yielded inconsistent results.
Purpose of the Study:
- To investigate the association between toenail levels of five trace elements (arsenic, copper, chromium, iron, zinc) and the risk of developing breast cancer.
- To examine potential differences in these associations based on menopausal status.
Main Methods:
- A cohort study of 62,641 US women, free of breast cancer at baseline (1982).
- Toenail clippings were collected for trace element analysis.
- Follow-up for 4 years identified 433 breast cancer cases matched with controls.
- Statistical analysis included odds ratios adjusted for known breast cancer risk factors.
Main Results:
- No significant associations were observed between toenail levels of arsenic, copper, iron, or zinc and overall breast cancer risk.
- A marginally significant positive association between toenail chromium and breast cancer risk was noted in postmenopausal women (OR=1.71, 95% CI 0.87-3.35).
- An inverse association between chromium and breast cancer risk was observed in premenopausal women.
Conclusions:
- The study did not find convincing evidence that toenail levels of arsenic, copper, chromium, iron, or zinc are important risk factors for breast cancer in the general population.
- Further research is needed to clarify the role of chromium, particularly considering the differing associations by menopausal status and the limitations in toenail element validity data.