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To the Editor: Multiple reproductive factors affect a woman’s lifetime risk of developing breast cancer. Nulliparity confers an increased risk, whereas the total number of births is inversely correlated with cancer risk. The biological mechanisms underlying these relationships have not been fully clarified, although both hormonal and cellular changes are implicated.¹

The study by Dr Khosrotehrani and colleagues,² which demonstrates the presence of fetal microchimeric cells in multiple maternal tissues (breast not included in analysis), suggests a novel mechanism by which parity may lower breast cancer risk: that pregnancy-associated progenitor cells provide a protective effect against the development of breast cancer. Whether as part of the glandular elements or microenvironment of the breast, fetal derived cells might communicate signals that inhibit malignant transformation, tumor angiogenesis, or both.^3-4

I am interested to know if Khosrotehrani et al have analyzed maternal breast tissue and cancer specimens for fetal microchimerism. Also, is . . . [Full Text of this Article]

Richard C. Frank, MD
richard.frank@norwalkhealth.org
Whittingham Cancer Center at Norwalk Hospital
Norwalk, Conn

RELATED ARTICLE

Fetal Microchimeric Cells and Breast Cancer—Reply
Kirby L. Johnson, Kiarash Khosrotehrani, Dong Hyun Cha, Robert N. Salomon, and Diana W. Bianchi
JAMA. 2004;292(13):1552-1553.
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