Younger women who regularly eat red meat may have an increased risk of developing hormone receptor-positive breast cancer, a US study suggests.

Hormone receptor-positive breast cancers are characterised by tumors in which growth is stimulated by the levels of estrogen or progesterone circulating in the body.

Researchers from Harvard Medical School in Boston and Brigham and Women's Hospital studied more than 90,000 pre-menopausal women aged 26 to 46 who were part of the Nurses' Health Study II.

They followed the women from 1991 through 2003, and gathered information on red meat consumption through a series of questionnaires.

Every two years, the women reported whether or not they had developed breast cancer.

Cases were confirmed through hospital records.

The researchers identified 1,021 women who had developed breast cancer over the course of the study period.

Eunyoung Cho, Brigham and Women's Hospital: "This study suggests that dietary factors may be related to a woman's chance of developing this type of breast cancer."

There were 512 cases of cancers which were oestrogen and progesterone-receptor positive.

The researchers split the women into five groups based on how much red meat they ate and found that the highest intake of red meat, more than one and a half servings per day, had nearly double the risk of hormone receptor-positive breast cancer compared with those who ate three or fewer servings per week.

Lead researcher Eunyoung Cho, from Brigham and Women's Hospital, said: "This study suggests that dietary factors may be related to a woman's chance of developing this type of breast cancer, a disease that is on the rise in American women."

Cho suggests several biological factors that may be related to the link between red meat and hormone receptor-positive breast cancer, including carcinogens found in cooked or processed red meat, hormone treatments of cattle for growth purposes, and the type of iron found in red meat.

He added: "The reason why the amount of red meat consumed by a premenopausal women was related to her breast cancer risk is unknown, but this study shows that it has a strong association and that more research should be done to further explore this connection."

The study is published in the Archives of Internal Medicine, one of the JAMA/Archives journals.

Previous research has linked high levels of consumption of red meat with an increased risk of bowel cancer.

Research conducted by Imaginis shows that breast cancer is the second leading cause of cancer deaths in women (after lung cancer) worldwide and is the most common type of cancer found among women in the world.

According to figures from the World Health Organization (WHO), around 1.5 million people worldwide will be diagnosed with breast cancer in 2006.

Earlier detection and better treatments have improved mortality rates in recent years.

The majority of breast cancers will be treated with surgery to remove the tumour.

For more information about breast cancer, visit www.999breastcancer.com.

The article Red meat linked to breast cancer originally appeared on 999 Today