Women with a D-cup bra size are more likely to get breast cancer

Women with a large bra size at a young age are more likely to develop premeno-pausal breast cancer, according to the results of a Harvard University study.

Research based on almost 90,000 women shows 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 Harvard scientists claim in the report, published in the International Journal of Cancer, that their findings provide evidence that "mammary gland mass is associated with breast cancer risk among women with normal and lean body mass". There appeared to be no link between bra size and breast cancer in the case of overweight or obese women, they added.

The results also echoed the findings of previous studies that showed that pre-menopausal women who did not wear bras had half the risk of breast cancer compared to bra users.

The authors suggest that women who did not wear support were more likely to have smaller breasts.

Other research has shown that Asian women, who usually have smaller breasts, have a lower risk of the disease.

In the latest study, researchers 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-meno-pausal breast cancer.

The researchers then compared bra cup size at 20 with the risk of developing the disease.

The results show 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.

"Among women with a BMI of less than 25, bra cup sizes of B and D or larger were significantly associated with an increased risk of premenopausal breast cancer compared to women who reported A or smaller. Among women with a BMI greater than or equal to 25, bra cup size was not associated with breast cancer risk," added the researchers.

Exactly why larger cup size could increase the risk of breast cancer is not clear.

One theory is that the breast cancer risk may rise as the total number of mammary gland cells and breast size increase.

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

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

"Larger breasts may therefore represent higher exposures to oestrogens. This supports the notion that early life processes, which govern growth and maturation, can have an influence on breast cancer risk by increasing mammary gland mass," said the researchers.

"Several indirect lines of evidence support the theory that breast size may influence breast cancer risk. Breast cancer occurs more frequently in the left breast, and the left breast is typically slightly larger than the right breast, and breast cancer is overwhelmingly more common in women than in men."

However, Professor Michel Coleman, professor of epidemiology at the London School of Health and Tropical Medicine, sounded a note of caution in the interpretation of the results.

He said: "This study 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. But the study is not conclusive on its own, and needs to be replicated."