Women with large breasts have a higher incidence of breast cancer than those with average-sized breasts, according to a study by medical students and researchers at The University of Western Australia and BreastScreen WA.

Corresponding author UWA Clinical Associate Professor Liz Wylie said the study highlighted the importance of regular mammograms for all women, but particularly those with large breasts.

Breast cancer is the most common cancer among Australian women and the second most common cause of cancer-related deaths. As it is a non-preventable disease, early detection is vital.

Women with large breasts may be more likely to suffer breast cancer because there is more tissue available for neoplastic change and/or because larger breasts cause increased oestrogen levels. As women age, a larger proportion of them have larger breasts.

In the study published recently by the journal Elsevier*, data from almost 760,000 women aged from 40 to over 70 - of whom almost 55,000 had large breasts - was analysed. Women whose breasts had been surgically enlarged or reduced and those with a previous diagnosis of breast or ovarian cancer were not included in the study.

Large breasts were defined as those that required bigger mammogram film cassettes. Standard cassettes measure 18 x 24cm while bigger ones are 24 x 30cm.

Associate Professor Wylie said the study was noteworthy because Australia is facing an obesity epidemic. An increased body mass index is associated with a higher risk of developing post-menopausal breast cancer.

The study is entitled "Outcome of mammography in women with large breasts" and its three leading authors are UWA medical students.

*Elsevier is an associate journal of the Australasian Society for Breast Disease affiliated with the European Society of Breast Cancer specialists and is the official journal of the Breast Centres Network.

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