Do larger breasts increase breast cancer risk? What experts really say

Does size matter? A leading breast cancer surgeon has answered a burning question that many women ask, but few get a straight answer to.

It is a question often asked but rarely answered clearly: does having larger breasts increase your risk of breast cancer?

As breast cancer cases in young Aussie women increase at a concerning rate, this question has never been more pressing.

According to leading breast cancer surgeon and researcher Associate Professor Sanjay Warrier, the answer is more nuanced than a simple yes or no.

“Breast size in itself is not considered a direct or independent risk factor for breast cancer,” Professor Warrier told news.com.au.

“The assumption that larger breasts may increase risk lacks strong clinical evidence and is not supported by robust data.”

However, he urges women with larger breasts to still be proactive about their health, especially if they have other contributing risk factors such as a family history of breast cancer, a sedentary lifestyle, or hormonal influences.

Does breast size impact breast cancer risk? An expert has weighed in. Picture: iStock

Breast density a more important factor

More importantly, breast tissue composition, specifically breast density, plays a far more significant role in breast cancer risk than size alone, Prof Warrier said.

The BI-RADS (Breast Imaging Reporting and Data System) density scale is used to classify breast tissue, with categories C and D indicating higher density.

Women with smaller breasts can still have high breast density, which is why it’s important to check the scale.

High-density breast tissue is associated with a slightly increased risk of cancer and can make tumours more difficult to detect on standard mammograms, as dense tissue appears white on imaging, which is the same colour as potential tumours.

For women with larger breasts, tumours may also be more difficult to detect, sometimes leading to delayed diagnosis.

In these cases, contrast-enhanced mammography or a MRI is often recommended for improved clarity.

Breast density is a more important factor than size. Picture: iStock

Other factors to consider

Prof Warrier also highlighted that women with a higher Body Mass Index (BMI), which may correlate with larger breast size, are at a statistically higher risk of developing breast cancer, especially after menopause.

“Higher body weight means more fat tissue, which in turn increases oestrogen levels, leading to a higher risk of hormone receptor-positive breast cancers,” he said.

“Hormonal exposure across a woman’s lifespan, including early menarche, late menopause, and hormone replacement therapy, also elevates risk by increasing the duration of oestrogen exposure.”

High density breast tissue can make tumours more difficult to spot. Picture: iStock

A preventive approach

The key takeaway is that 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.

Prof Warrier advises women of all body types to adopt a preventive approach to breast health, incorporating self-examinations, regular screenings, a wholefood diet, physical activity, and limiting alcohol and processed food intake.

Taking a personalised approach to breast cancer screening is also increasingly regarded as best practice.

New research proves promising

While standard population-based screening generally begins at age 50, emerging evidence suggests that earlier and more frequent screening may benefit those at higher risk.

Landmark studies such as the PROCAS trial in the UK and the ROSA Project in Victoria are exploring risk-based models that take these variables into account.

These studies are helping to shape new guidelines for tailored screening strategies.

This may not only lead to earlier detection but also reduce the need for aggressive treatments and improve overall outcomes by catching cancers at a more manageable stage.

Professor Sanjay Warrier is a leading Australian breast cancer surgeon and researcher. Picture: Supplied

Breast cancer diagnoses on the rise

It comes as breast cancer diagnoses continue to rise among young women in Australia.

Breast cancer is estimated to be the most commonly diagnosed cancer in women aged 20-39, and every day around three women under 40 are diagnosed with breast cancer.

Breast cancers in young women tend to have different characteristics and poorer survival outcomes compared with older women, making early detection vital.

If you have concerns about your breast cancer risk, make an appointment with your GP to discuss your personal situation and the best screening options for you.