Determining how Pineal Melatonin affects Breast Cancer incidence and severity

Project Investigator: Stewart Thompson

Project Description:  One in eight women get breast cancer in their lives and 40,000 women die from it every year. The best way to save these lives is to stop them getting cancer in the first place.

Light controls the body clock, sleep and important hormones in our body. In this way, light adapts us to day and night, and the changing seasons. This also means that switching the lights on at night can disrupt the normal function of our brain and body. Studies suggest that light-at-night increases breast cancer risk by as much as 30%. Consistent with this idea, completely blind women get breast cancer about half as often as women with normal vision.

One possible reason for this effect is that light-at-night suppresses production of the pineal hormone, melatonin. So we want to know, does absence of pineal melatonin cause increased breast cancer, or worse types of breast cancer.

We remove the pineal gland from mice, and compare them to identical mice that have their pineal gland. Our early findings do show an increase in worse types of breast cancer in mice with no pineal melatonin. This study will show whether this finding is real, and will give us more detail on what is different about the breast cancer in mice with no pineal melatonin.

So our study could provide compelling evidence that we should avoid suppressing melatonin, and will give us some idea of how deficits in melatonin affect breast cancer.

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