Birth Size Linked to Breast Cancer Risk (HealthDay)

TUESDAY, Sept. 30 (HealthDay News) -- Women who are heavier and longerat birth are at increased risk of developing breast cancer later in life,British researchers report.

In fact, as birth weight and length increases, so does the risk forbreast cancer, according to the results of a study published in the Sept.30 online edition of PLoS Medicine.

"These researchers have documented in unequivocal terms that largerbirth size is associated with increased breast cancer risk several decadeslater," said Dr. Dimitrios Trichopoulos, the Vincent L. Gregory Professorof Cancer Prevention at Harvard University School of Public HealthDepartment of Epidemiology and author of an accompanying journaleditorial.

Birth size reflects, to a considerable extent, the effects of theintrauterine environment on the fetus, Trichopoulos noted. "To this day,they had not been sufficiently appreciated by the scientific community,because each individual study could not provide conclusive evidence. Weare facing now a new reality: that breast cancer has its origins severaldecades before its clinical appearance," he said.

For the study, a research team led by Dr. Isabel dos Santos Silva, aprofessor of epidemiology at the London School of Hygiene and TropicalMedicine, collected data on more than 600,000 women, 22,058 of whom hadbreast cancer. The data came from 32 studies.

The researchers found that women who were heavier and longer at birthhad increased risk for breast cancer as adults. An analysis of birthrecords, among these women, found that for every 17.6 ounces of birthweight, the risk for breast cancer increased 7 percent.

In addition, birth length and head circumference were also associatedwith an increased risk of breast cancer. The strongest association betweensize at birth and an increased risk for breast cancer was seen for birthlength, the researchers reported.

"Recognition of early life influences are critical in the etiology ofbreast cancer and helps to explain why several adult life primaryprevention practices -- as distinct to secondary prevention ones focusingon early detection -- have been of limited effectiveness," Trichopoulossaid.

"Prevention of breast cancer needs to take into account the very longnatural history of the disease," he added.

Expert reaction to the new research was fairly guarded.

"There's good evidence for these findings, but there is really noclinical relevance for them," said Debbie Saslow, director of breast andgynecologic cancer at the American Cancer Society.

"There is nothing that women should do differently to try to havesmaller babies, or women who were born with a longer length or larger headcircumference should do anything differently when they grow up or getscreened differently, or consider themselves at high risk -- it's reallyjust a research issue," Saslow said.

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