Do larger breasts increase breast cancer risk? The facts behind the question

It is a question often asked but rarely answered with clarity - do women with larger breasts have a higher risk of developing breast cancer? According to leading breast cancer surgeon and researcher Associate Professor Sanjay Warrier, the answer is more nuanced than a simple yes or no.

"There is no direct evidence that breast size alone increases a woman's risk of developing breast cancer," Associate Professor Warrier said.

"However, certain factors associated with larger breast size can influence risk and make detection more challenging."

Associate Professor Warrier is one of the world's leading breast health and breast cancer surgeons who has built a highly respected practice in Sydney.  The practice spans three locations with its main surgical centre located at the Chris O'Brien Lifehouse in Camperdown, and the other sites at BMA House, Macquarie Street, Sydney and Bondi Junction Medical, Oxford Street, Bondi Junction.

In addition to Associate Professor Warrier's breast health and surgical work, he also dedicates considerable time to research exploring and developing advancements in breast cancer detection and treatments to improve outcomes for patients.  He also codeveloped Australasia's first Master of Advanced Surgery (Breast Surgery) which is delivered through the University of Sydney. 

"Denser breast tissue, higher body mass index (BMI) and hormonal influences often intersect with breast size and it's these factors, not size alone, that play a more significant role in cancer risk," Associate Professor Warrier said. 

"Larger breasts can sometimes correlate with a higher proportion of fatty tissue, particularly in postmenopausal women and this tissue can be hormonally active.

"We know that increased estrogen levels over time can raise the risk of hormone-receptor-positive breast cancers."

He also highlighted that women with a higher BMI, which may correspond with larger breast size, are at a statistically higher risk of developing breast cancer, especially after menopause. 

"Fat tissue produces estrogen and higher levels of circulating estrogen have been linked to breast cancer development," he explained.

There are also important implications for detection.

"In women with larger breasts, tumours may be more difficult to detect through physical examination or even imaging. This can sometimes delay diagnosis," Associate Professor Warrier said.

"It underscores the importance of regular screenings and working with medical teams who are experienced in imaging larger and denser breast tissue."

While breast size itself is not a risk factor, women with larger breasts should be proactive about their health, particularly if they have other contributing risk factors such as a family history of breast cancer, a sedentary lifestyle or hormonal influences.

"The key takeaway is this, breast size alone does not determine your cancer risk. It's the broader picture of lifestyle, hormonal exposure, weight, family history and breast density that matters," Associate Professor Warrier said.

He advises women of all body types to adopt a preventative approach to breast health that includes self-examinations, regular screenings, a whole-food diet, physical activity and limiting alcohol and processed food intake.

"Understanding your own risk profile is vital. Every woman's body is different and personalised prevention starts with being informed," he added.

More information on breast cancer detection and screening is available at www.drsanjaywarrier.com.au.

About Associate Professor Sanjay Warrier

Associate Professor Sanjay Warrier is a past President and current committee member of Breast Surgeons of Australia and New Zealand (BreastSurgANZ). His views are those of his own, not BreastSurgANZ. Associate Professor Warrier's surgery is located at the Chris O'Brien Lifehouse and he also has clinics at Oxford Street, Bondi Junction and Macquarie Street, Sydney. He is published in numerous peer-reviewed journals and won the Royal Prince Alfred Hospital's Patron's Prize for best scientific research.