Hormone therapy raises breast cancer risk - study

A new study published online Thursday in the Journal of the National Cancer Institute suggests that use of hormone replacement therapy may raise the risk of breast cancer. This association between hormone therapy and increased risk for the disease has been reported early.

The study led by the Canadian Cancer Society found reduced use of hormone therapy was associated with decreased risk of breast cancer found between 2002 and 2004 among post-menopausal Canadian women.

Many Canadian women have stopped taking hormones after a U.S. clinical trial which was terminated earlier than scheduled found evidence that hormone replacement therapy was linked increased risk of breast cancer, heart attack, stroke and blood clots in the lungs.

Prithwish De, an epidemiologist with the Canadian Cancer Society and lead author of the current study was quoted as saying "We saw a 10 per cent drop in the incidence rate of breast cancer from 296 per 100,000 women to about 278 per 100,000."

The study was observational, but the association is likely causal as hormones are known to be a risk factor.  It has been known for long that women who entered puberty early are expected to expose themselves to estrogen for a longer period, about 10 to 15 years longer, and those women are at higher risk of breast cancer.

This is because estrogen promotes the growth of breast cancer cells even though the hormone does not initiate the carcinogenesis.

Thormone therapy is indicated to help postmenopausal women with some menopausal symptoms like hot flashes.

In the United States, one out of 8 women are expected to be diagnosed with breast cancer in their life time. The disease is diagnosed in more than 175,000 individuals each year in the country and about 50,000 will die from the malignancy.

Following a healthy lifestyle is key to preventing breast cancer, which in many cases is preventable.  High fat, high animal protein, and processed meat among other things are known dietary factors that boost the risk of breast cancer while many other lifestyle parameters such as plant-based diet, physical activity and breastfeeding are preventive against the disease.

David Liu