Being a D cup at 20 could mean breast cancer at 40

According to researchers, women with a large bra size at a young age are more likely to develop pre-menopausal breast cancer.

The researchers at Harvard University based their study on almost 90,000 women and they say results show that lean women of normal weight who had a D-cup at the age of 20 were significantly more likely to go on to develop the cancer than those wearing an A-cup.

The scientists say that their findings provide evidence that "mammary gland mass is associated with breast cancer risk among women with normal and lean body mass.

But they also say that there appeared to be no link between bra size and breast cancer in the case of overweight or obese women.

Previous studies have shown that pre-menopausal women who did not wear bras had half the risk of breast cancer compared to bra users, and that Asian women, who usually have smaller breasts, have a lower risk of the disease.

But they do suggest that women who did not wear support were far more likely to have smaller breasts.

The researchers at Harvard used data from 89,268 women who were first recruited in 1989 when they were aged between 25 and 42.

They completed health and lifestyle questionnaires every two years and were also asked for their bra size at the age of 20.

Height, weight and body mass index (BMI) at 18 were recorded, as were diet, alcohol consumption, exercise, contraceptive use and family history of breast cancer.

The questionnaires recorded any cases of breast cancer, and, by 2001 a total of 803 women had been diagnosed with pre-menopausal breast cancer.

Bra cup size at 20 was then compared with the risk of developing the disease, and the results showed that for women with a normal body mass index, larger bra cup sizes were significantly associated with an increased risk.

However, among overweight or obese women, no link was detected between bra cup size and breast cancer.

It is unclear why larger cup size might increase the risk of breast cancer but one theory suggests that the breast cancer risk may rise as the total number of mammary gland cells and breast size increase.

The study also says that the size and development of the breast may be affected by early life events, such as diet and hormonal exposure.

According to the research, oestrogens also have an effect on mammary gland growth and development, and larger breasts may be a marker of higher exposures to these hormones.

There is also other evidence which supports the theory that breast size may influence breast cancer risk, as breast cancer occurs more frequently in the left breast, and the left breast is typically slightly larger than the right breast.

Breast cancer is also far more common in women than in men.

Experts are cautious however and suggest that although the interpretation of the results provides a degree of evidence that large breasts at a young age in thinner women indicate some increase in risk of breast cancer before the menopause, the study is not conclusive on its own, and needs to be replicated.

The report is published in the current edition of the International Journal of Cancer.