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In Reply: Dr Frank describes reproductive factors and their association with lifetime risk of developing breast cancer in women, such as nulliparity conferring an increased risk and increasing parity being inversely correlated with risk. These associations suggest a protective effect of pregnancy, with hormonal and cellular changes being implicated,¹ although we agree with Frank that this effect could also be due to a novel mechanism involving the acquisition of fetal cells during pregnancy. The results of a study by Artlett et al² suggest a similarly protective effect of pregnancy on disease course and cause of death in systemic sclerosis, as they reported earlier onset of disease, more severe lung involvement, and higher rate of death in women who had never been pregnant compared with those who had had prior pregnancies.

Our group to date has not investigated whether fetal cell microchimerism is associated with breast cancer. However, we have . . . [Full Text of this Article]

Kirby L. Johnson, PhD
kjohnson@tufts-nemc.org

Kiarash Khosrotehrani, MD; Dong Hyun Cha, MD; Robert N. Salomon, MD; Diana W. Bianchi, MD
Division of Genetics
Department of Pediatrics
Tufts-New England Medical Center
Boston, Mass