What the shape, size and density of your breasts can tell you about your risk of cancer

Our expert debunks the myths when it comes to breast cancer risk

It’s the most common type of cancer, affecting one in seven women so it’s understandable that women are asking lots of questions online about whether the shape, size and density of their breasts can impact their risk. It’s good that awareness is being raised about the importance of at-home self-breast checking – it is key to picking up a diagnosis early, and improving outcomes. But it’s important to know the facts and not be alarmed by misinformation circulating online. That’s why here, I’m running through the myths to help you separate fact from fiction.
Breast tissue is composed of three types of tissue: fibrous connective tissue, glandular tissue and fat. You may be told you have “dense breast tissue”, a term that refers to the ratio of more dense fibrous tissue and glandular tissue, compared to fatty tissue in a person’s breast.
Women who are pre-menopausal or perimenopausal seem to have more dense breasts, compared to those who have gone through the menopause. Breast density declines with age. It’s also been found that people from Asian, or Afro-Caribbean descent are more likely to have dense breast tissue and it can also run in families.
Those with dense breast tissue are two to three times more likely to develop breast cancer, but there isn’t enough scientific evidence available to explain why that is.
What we do know is that having dense breasts can impact the efficacy of the breast cancer screening, as dense tissue can make potentially cancerous breast lumps harder to pick up on mammograms and ultrasound scans.
It’s estimated that approximately 40 per cent of women over 40 have dense breasts. If you’ve been told you are one of them, it’s important to remember that this is just one risk factor for developing cancer, alongside many others which may be more within your control.
Breast density alone does not predict your risk of developing cancer. Minimising your risk where possible through exercise, diet, and avoiding smoking and alcohol. It’s also crucial that you attend mammogram breast screening when invited, as although more of a diagnostic challenge, it is still possible to pick them up, amongst a more dense breast.
There’s no evidence to suggest a larger breast size increases cancer risk, however it may make self-checking more difficult, and someone may be more likely to miss a small and early cancer, compared to those with smaller breast tissue. Regular breast checking is important because it will help you to find a technique that works and know what is normal for you.
Look and feel your breasts once a month to check for any change in size or shape, or if the breasts look more asymmetrical. Pay attention to your skin too, and any signs of puckering and tethering (sometimes resembling orange peel). If you notice changes in your nipples including inversion, discharging, bleeding or crusting, see your GP. After having a thorough look, feel each breast in turn for any lumps or bumps. Don’t forget to feel into the armpit and up into the collar bone on each side, as these are commonly missed areas.
No, the shape of your breast does not increase cancer risk. Breast shape and size is hugely variable between individuals. It’s also normal to have some differences in size and shape between your own two breasts.
What is concerning is if you notice a change in the size or shape of your breast, as this may indicate there is a mass. Many lumps can be due to fluid filled cysts, fatty lumps or fibrous tissue but it’s important to get them checked.
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Approximately half of breast cancer cases develop in women with no clear risk factors. The biggest risk factor for developing breast cancer is being female, with only 1 per cent of breast cancers occurring in men. Others include increasing age, a family history of breast cancer and modifiable risk factors such as smoking, obesity, alcohol use. There is also a link between hormonal therapy including the Oral Contraceptive Pill and Hormone Replacement Therapy for menopause and you should be able to discuss your individual risk with your GP.
It’s a good idea to assess your own risk of developing breast cancer. Some risk factors including family history, age or gender are unavoidable. However, there are certain areas you can focus your attention on such as stopping smoking, reducing or cutting out alcohol, managing weight, engaging with breast cancer screening, and checking your breasts regularly at home.
If you notice something doesn’t feel quite right, it’s important to get it checked out, and advocate for yourself when seeing your doctor. While most lumps turn out not to be cancerous, a second opinion is always a good idea.