Letters Section Editor: Robert M. Golub,
MD, Senior Editor.
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.
Johnson KL, Khosrotehrani K, Cha DH, Salomon RN, Bianchi DW. Fetal Microchimeric Cells and Breast Cancer—Reply. JAMA. 2004;292(13):1552-1553. doi:10.1001/jama.292.13.1552-b