It has been common knowledge that having a baby by the age of 20 cuts a woman's future risk of breast cancer in half, but now U.S. scientists at the Fox Chase Cancer Centre, Philadelphia, have shown that the hormone that heralds pregnancy could offer a way to prevent breast cancer.
The hormone hCG, which is produced by the placenta in pregnancy, appears to be responsible for this protection.
In their experiment, Dr Irma Russo and colleagues compared virgin rats treated with a daily hCG injection, virgin rats treated with oestrogen and progesterone, untreated virgin rats and pregnant rats. It was revealed how hCG changes breast cells' DNA, making them more resilient to cancerous changes.
Breast cells do not reach full maturity until a woman has had a full-term pregnancy, and the protection conferred was specific to the hormone hCG and which was not found with other female hormones. Only the pregnant rats and the rats treated with hCG had the permanent genetic changes that are protective against breast cancer. Russo says this hormone might be useful for breast cancer prevention in women and hopes in future, it might be possible to offer women who do not wish to or are unable to have a baby, the same protection.
Dr Leslie Bernstein, of the University of California School of Medicine in the US, in other research looked at 744 women with breast cancer and 744 women without breast cancer who were of a similar age, race and pregnancy history (ranging from none to many past pregnancies), and found a very modest reduction in breast cancer risk overall with the hCG shots but saw a much stronger reduction of risk in women who had never had a full-term pregnancy, however, if the woman was very obese, this protection was not seen.
She feels the results are worth pursuing as a preventative tool as the treatment does not appear to cause any harm.
In the mid-90s in the US, there was a trend for some women to include hCG injections as part of a weight loss programme.