breast cancer risk marker

A recent study has investigated whether levels of specific immune cells could predict breast cancer risk.

A leukocyte is a white blood cell of the immune system that protects the body against infectious disease and is produced in the bone marrow. There are several sub-types of leukocytes, among them are monocytes and B cells.  A monocyte is the largest type of leukocyte and can differentiate into other cells. B cells are also known as B lymphocytes and are a type of white blood cell that produces antibodies.

A recent study published in the Journal of the American Medical Association found that specific leukocyte subtypes are associated with breast cancer risk months to years after blood collection. The study group consisted of a small cohort that was taken from the Sister Study – a larger breast cancer study that enrolled over fifty thousand women.

The researchers examined six leukocyte subtypes. These were B cells, natural killer cells, CD8 and CD4 T cells, monocytes, and granulocytes. Blood was collected from the women and complete blood cell count data was analyzed. Methylation-derived neutrophil-to-lymphocyte ratio was determined along with the leukocyte proportions.  The researchers also looked at leukocyte subtype stability over periods of time and found that the leukocyte subtypes were generally stable.

Increased levels of B cells are positively associated with breast cancer risk

The researchers found that circulating proportions of B cells were positively associated with breast cancer risk, especially among premenopausal women. The women who developed breast cancer tended to be older, less physically active, and be older at menopause onset. Age was positively correlated with natural killer cells but not with B cells. Women with proportions of natural killer cells, CD8, and CD4 T cells greater than the subcohort median were at greater breast cancer risk.  Women with elevated granulocytes or CD8 T cells were more likely to experience breast cancer risk four years after blood collection.

Circulating proportions of monocytes were inversely associated with breast cancer risk

It is important to note that this study was largely observational and could only assess the proportions of leukocytes at the time when follow-up began. The effects of leukocyte changes could not be assessed.

This study contributes to knowledge of how the immune system may be involved in breast cancer risk. In future it may be possible to monitor women for breast cancer risk depending on their immune system profile.   According to the researchers, “Circulating leukocyte profiles may be altered before clinical diagnoses of breast cancer and may be time-dependent markers for breast cancer risk, particularly among premenopausal women.”

Written by Katrina F. Zafer, BSc


  1. Kresovich, J. K., O’Brien, K. M., Zongli, X. (2020). Prediagnostic Immune Cell Profiles and Breast Cancer. Journal of the American Medical Association.

Image by Mekis from Pixabay

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