Placental Health and Breast Cancer Risk

A team of California researchers has found that three indicators of placental health during a woman's pregnancy may serve as markers for her future risk of breast cancer.

Writing in the Journal of the National Cancer Institute, Barbara Cohen, Ph.D. of the Public Health Institute in Berkeley, California and colleagues noted that three factors-a smaller placenta, an increase in blood pressure from the second to third trimester, and a condition called maternal floor infarction of the placenta-are associated with substantial reductions in subsequent breast cancer risk for the mothers.

The researchers reviewed the medical records of 3,804 women in the San Francisco area who were pregnant between 1959 and 1967. They focused on clinical measurements that were recorded during prenatal care visits and during labor and delivery. Shortly after delivery, the placenta was weighed and its largest diameter was measured. In addition, the placenta was examined for maternal floor infarction, a condition in which excessive fibrin is deposited on the maternal side of the placenta.

The researchers then tracked the rates of eventual breast cancer for these women through the California Cancer Registry. As of 1997, 146 of the women had developed invasive breast cancer, with a mean age at diagnosis of 54.2 years.

The authors found that women with the highest increase in blood pressure (top 25 percent) had a 51 percent reduction in breast cancer incidence. Similarly, maternal floor infarction of the placenta was associated with a 60 percent reduction in breast cancer. Also, the risk of breast cancer was lower in women with smaller placentas, but not to such a significant degree.

If all three of these factors were present, they wrote, the reduction in breast cancer risk was a remarkable 94 percent.

The authors suggested that physicians could use such measures of placental health as important new tools for recommending potential screening and prevention strategies to women. "Elucidating the mechanisms for these associations could provide clues to breast cancer prevention and treatment," they wrote.

In an accompanying editorial, Drs. Robert Hoover and Rebecca Troisi called for more studies to further evaluate these placental health factors and their role in determining eventual breast cancer risk. They noted that that such information, combined with our rapidly evolving understanding of the molecular evolution of breast cancer, could produce individually targeted prevention strategies in the years ahead.

SOURCES:
Journal of the National Cancer Institute, August 1, 2001; 93:1133-1140
National Cancer Institute (http://www.nci.nih.gov)

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