# HIGH SELENIUM INTAKE AND RISK OF HUMAN CANCER

> **NIH NIH R01** · HARVARD MEDICAL SCHOOL · 1988 · $116,641

## Abstract

We propose to continue to conduct a case-control study to test the
hypothesis that persons with relatively high levels of selenium are at
decreased risk of developing cancer of the breast, lung, and large bowel.
We have recently expanded the study to include cancer of the prostate,
bladder, and ovary.  The study enrolls nearly all incident cases that occur
in the nine-county region surrounding Rapid City, SD, and a random sample
of general population controls from this area.  Selenium intake is measured
by neutron activation analysis of toenail clippings from all subjects,
providing an assessment of selenium status approximately one year
previously.  Information on potential modifiers and confounders, including
other dietary variables, is collected by interview and questionnaire.

Results from other studies using prospectively collected specimens suggest
that low levels of selenium may confer an increased risk of cancer in
humans.  However, it is not known whether only individuals at the lowest
extreme are at increased risk, or whether high levels (and therefore
perhaps supplementation) confers protection.  The Rapid City region
provides an ideal setting because the selenium levels there are among the
highest in the country, and the variation among individuals is unusually
large.  The current study has the advantages of an existing smooth and
efficient operation, a high degree of cooperation from participants and
health care providers, and a population based design with nearly complete
ascertainment of cases.  To date over 280 cases and over 160 controls have
been enrolled, with cooperation rates of 98% and 93%, respectively.
Initial results show a strong protective trend for lung cancer, but no
significant association with cancer of the breast and large bowel.
However, the 95% confidence limits will still include relative risks of
potential importance which cannot be excluded without expanding the present
study.  Since tissue selenium levels are easily increased by
supplementation, a precise estimate of associations with cancer risk have
considerable potential practical relevance.  We thus propose to double the
sample size of this study to better quantify these relatioships.

## Key facts

- **NIH application ID:** 3172041
- **Project number:** 5R01CA034321-06
- **Recipient organization:** HARVARD MEDICAL SCHOOL
- **SAM.gov UEI:** JDLVAVGYJQ21
- **Principal Investigator:** Walter C. Willett
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1988
- **Award amount:** $116,641
- **Award type:** 5
- **Project period:** 1983-06-01 → 1990-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3172041

## Citation

> US National Institutes of Health, RePORTER application 3172041, HIGH SELENIUM INTAKE AND RISK OF HUMAN CANCER (5R01CA034321-06). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3172041. Licensed CC0.

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