Birth size and breast cancer

Breast cancer is the leading cause of cancer deaths among women worldwide and according to the American Cancer Society, they estimate about 465,000 women died of breast cancer globally in 2007, and 1.3 million new cases were diagnosed.

As in most developed countries, we are seeing a declining death rate from breast cancer that is somewhat attributed to early detection through mammography screening and better treatment programs.

There is a recent study suggesting that what happens in the womb may cause cancer later in life, particularly in larger women who give birth to longer babies. Other research, published in the Public Library of Science journal PloS Medicine, also indicates links between birth size and breast cancer.

The current research was comprised of 32 studies of more than 600,000 women, mainly in developed countries and it included more than 22,000 women who had breast cancer.

The researchers found a strong correlation with birth size, birth length, and head circumference, with birth length demonstrating the strongest link. Women with recorded birth weights of 4 kilograms or more had a 12 percent higher chance of breast cancer than babies weighing 3 to 3.5 kilograms at birth. They also estimated that birth size may be responsible for up to 5 percent of all breast cancers in women up to the age of 80.

The rationale behind the theory is the probable link between estrogen and human growth hormone. Further research will be needed to determine the truth behind the theory.