Breast Cancer Awareness

Breast cancer is the commonest cancer diagnosed globally and in the UK, where it represents 15% of all new cancer diagnoses [1] [2]. In 2020, there were 2.26 million women diagnosed with breast cancer and 685,000 deaths globally [2]. Most women diagnosed with breast cancer are over the age of 50 (82% in the UK), but the condition can also affect younger women, especially where there is a prominent family history of the condition. Whilst many cases of breast cancer are unfortunately not preventable, studies show that around 30% of UK breast cancer cases are preventable through changes in lifestyle, the equivalent of around 17,00 new cases each year [2]. That’s a huge number, and as preventive medicine specialists we want to raise awareness of how people can reduce their risk of breast cancer, as well as the importance of regular self-checking and breast screening.

What is breast cancer? (The biology of breast cancer)

Breast cancer is a disease in which malignant (cancer) cells form in the tissues of the breast. These cells have the capacity to form tumours (a mass of abnormal cells) and spread to other parts of the body. Importantly, not all tumours (masses of abnormal cells) are cancer, and not all breast tumours are breast cancer.

There are two main types of breast tumours: cancerous (malignant) tumours or benign (non-malignant) tumours. Whether a tumour is classified as cancerous or benign depends on the composition of cells in the tumour and how aggressive those cells are. For this reason, a sample of tumour cells (a biopsy) is often required to confirm whether or not a tumour is cancerous. The term ‘aggressive’ describes the capacity of tumour cells to invade or spread to other body tissues, beyond the tissue in which they originate (in this case, beyond the breast). If a tumour has the capacity to spread beyond its original tissue, it is said to be a cancerous tumour, or simply ‘cancer’.

Benign breast tumours do not have the capacity to spread beyond the breast tissue, are usually slow growing and often require no treatment. However, benign tumours may continue to grow, and over time may start to press on neighbouring structures, causing pain or other problems. In these situations, the tumour may be surgically removed in order to relieve pain or prevent complications. There are several benign breast conditions that may result in changes to the breast tissue or the formation of benign tumours, including Lobular Carcinoma In-Situ (LCIS) which is not a cancer https://www.macmillan.org.uk/cancer-information-and-support/worried-about-cancer/pre-cancerous-and-genetic-conditions/lobular-carcinoma-in-situ.

To read more about benign breast conditions, please see here. https://www.nationalbreastcancer.org/breast-tumors/

https://www.macmillan.org.uk/cancer-information-and-support/breast-cancer/types-of-breast-cancer

https://breastcancernow.org/information-support/have-i-got-breast-cancer/breast-lumps-benign-not-cancer-breast-conditions

What are the different types of breast cancer?

There are many different types of breast cancer and the terminology used to describe them can be confusing, not least because the different categories can overlap. Here we will outline the most common types of breast cancer, and commonest ways in which they can be categorised.

Breast cancer can be broadly divided into ‘non-invasive’ and ‘invasive’ categories.

Non-invasive (also called in-situ) breast cancer has not spread beyond the breast’s milk ducts or lobules and is often referred to as Ductal Carcinoma In-Situ (DCIS) https://www.macmillan.org.uk/cancer-information-and-support/breast-cancer/ductal-carcinoma-in-situ-dcis . This is the earliest form of breast cancer, and if left untreated (or undiagnosed) can progress to invasive breast cancer. DCIS may show up on a mammogram (x-ray of the breast) and is often diagnosed during breast screening.

Invasive breast cancer, which comprises most breast cancers at diagnosis, is cancer that has spread beyond the ducts or lobules, and into the surrounding breast tissue. Invasive breast cancer can be further sub-divided into ‘non-special types’ and ‘special types’, depending on the visual appearance of the cancer cells under a microscope. Non-special type (NST) breast cancers (also called ‘not otherwise specified’ or NOS), who’s cells do not have any ‘special’ features under the microscope, include Invasive Ductal Carcinoma (IDC) https://www.nationalbreastcancer.org/invasive-ductal-carcinoma which is the commonest type of breast cancer overall, comprising 70-80% of all cases. Special-type breast cancers are much rarer and have cells with characteristic features visible under the microscope. These cancers are usually named according to the appearance of their cells, and include tubular, medullary, mucinous or cribriform types. Malignant phyllodes (https://www.macmillan.org.uk/cancer-information-and-support/breast-cancer/phyllodes-tumours) and angiosarcoma (https://www.macmillan.org.uk/cancer-information-and-support/soft-tissue-sarcoma/types) are also included under special-types. Other rare types of breast cancer include Invasive Lobular Breast Cancer (ILC) https://www.nationalbreastcancer.org/invasive-lobular-cancer, inflammatory breast cancer (IBC) https://www.nationalbreastcancer.org/inflammatory-breast-cancer and Paget’s disease of the breast https://www.nationalbreastcancer.org/other-types-of-breast-cancer[3].

Breast cancers can also be categorised according to whether their cells have receptors for certain hormones (hormone receptor-positive cancers). These hormones include oestrogen, progesterone and/or a special protein called HER-2 (HER-2 positive breast cancer). Around 75% of breast cancers are ‘oestrogen receptor positive’ cancers, meaning their cells have additional oestrogen receptors and depend on oestrogen to grow. However, some breast cancers (around 15%) are ‘triple negative’ cancers, meaning they do not have additional receptors for any of the above three hormones. Triple negative breast cancers are more common in younger women and tend to be more aggressive and difficult to treat [4].

What causes breast cancer?

The exact causes of breast cancer are not fully understood, and it may not always be possible for doctors to say precisely what caused breast cancer to develop in an individual. Like other cancers however, breast cancer occurs when abnormal cells (in the breast) grow and replicate rapidly in an uncontrolled manner. These abnormal cells develop due to one or more mutations in their DNA, specifically the sections of DNA that normally keep cell growth and division under tight control. Whilst it is not always possible to determine what caused these changes in the DNA to occur, there are important known risk factors that affect the likelihood of developing breast cancer. These risk factors are either ‘modifiable’ (such as smoking or alcohol excess) or ‘non-modifiable’ (such as age and biological sex). Here we discuss the most prominent risk factors for breast cancer, but for a more comprehensive overview of risk factors, please see the Breast Cancer UK website https://www.breastcanceruk.org.uk/about-breast-cancer/are-you-susceptible-to-breast-cancer/

Risk factors: non-modifiable factors

Non-modifiable risk factors for developing breast cancer include biological sex, age, family history, previous breast cancer (or breast lump), lifetime exposure to oestrogen and having especially dense breast tissue. Breast cancer occurs in both women and men, but women are at greater risk due to their enhanced breast development and their greater lifetime exposure to oestrogens, which stimulate greater cell division and growth in the breast tissue and can make oestrogen receptor-positive cancers grow faster [5].

The risk of breast cancer also increases with age and is most common in women over age 50 who have completed the menopause. Around 80% of breast cancers occur in women over 50, therefore women between the ages of 50 and 70 are advised to screen for breast cancer every 3 years, as part of the NHS Breast Screening Programme https://www.nhs.uk/conditions/breast-screening-mammogram/ . Women over the age of 70 are still eligible for screening and can arrange this through their GP or local screening service.

If an individual has close relatives who have been diagnosed with breast or ovarian cancer, they may be at higher risk of developing breast cancer themselves. However, most cases of breast cancer are not familial, and because breast cancer is the commonest cancer in women it is possible to have multiple close relatives affected by chance [6]. However, having a first degree relative (mother, sibling or daughter) who has developed breast cancer, especially at a young age, approximately doubles your lifetime risk [7].

Additionally, mutations (or faults) in certain genes, which can be passed on from parent to child, can increase the risk of developing breast cancer. These faulty genes are thankfully rare but can occur in both women and men. The most well know are the BRCA1 and BRCA2 genes, mutations in which can increase risk of breast, ovarian, prostate and pancreatic cancer and are present in around 1 in every 400 people. Researchers estimate that 70% of women with faulty BRCA1 or BRCA2 genes will go on to develop breast cancer by the age of 80 [8]. Other genes associated with an increased breast cancer risk include TP53 and CHEK2 [6]. Those with a known family history of breast or other specific cancers are encouraged to speak to their GP, who will determine whether predictive genetic testing (https://www.cancerresearchuk.org/about-cancer/causes-of-cancer/inherited-cancer-genes-and-increased-cancer-risk/genetic-testing-for-cancer-risk ) for cancer risk is appropriate.

People with a previous history of breast cancer or early non-invasive cancer cell changes in ducts (DCIS), are at a greater risk of developing breast cancer again, in either breast. Certain other benign breast conditions or lumps can also increase the risk of developing breast cancer in future. These include atypical ductal hyperplasia and lobular carcinoma in situ. Women with especially dense breast tissue may also be a higher risk of developing breast cancer, due to the greater number of lobular (glandular) cells that have the potential to become cancerous [6].

Regarding oestrogen, the female sex hormone produced naturally by the ovaries, research suggests that a greater lifetime exposure to oestrogen (whether higher ‘dose’ or longer duration) may slightly increase a woman’s risk of developing breast cancer. This is thought to be because oestrogen stimulates a higher rate of growth and replication in breast tissue, meaning that DNA mutations are more likely to occur in cells, potentially leading to cancer. Subsequently, women who started menstruation at a younger age (under 12) and those who entered the menopause later (after 54) may be at higher risk than other women. For the same reason, women who have never had children or had children after age 30, may have higher risk due to the natural interruption in oestrogen production that accompanies pregnancy.

Risk factors: modifiable factors

Important modifiable risk factors for breast cancer include being overweight, lack of physical activity, excess alcohol consumption, radiation exposure, smoking and the use of combined Hormone Replacement Therapy. As previously mentioned, having children after age 30 (or not having children at all) can increase the risk for women, whereas breastfeeding can reduce the risk of future breast cancer development [5].

As with many cancers, obesity, lack of exercise, excessive alcohol, radiation and smoking can all increase the risk of developing breast cancer. These modifiable risk factors present important opportunities for breast (and other) cancer prevention, which will be discussed further in the ‘prevention’ section below.

Regarding Hormone Replacement Therapy (HRT), there is often confusion around whether this can increase the risk of breast cancer in women. Most types of HRT can increase the risk of breast, ovarian and uterine (womb) cancer [9]. However, the increased risk is small and also depends on the type of HRT being used and the duration over which it is taken. Combined HRT (containing progesterone and oestrogen) carries a greater increase in risk than oestrogen only HRT, although both do carry and increased risk of breast cancer. HRT that is taken for less than one year will not increase overall breast cancer risk, whereas taking HRT for longer than a year increases breast cancer risk more than a woman who has never taken HRT. The increased risk of breast cancer falls after cessation of HRT, but some increased risk remains for more than 10 years, compared with a woman who has never taken HRT [10].

An important exception is vaginal oestrogens (creams or pessaries), which do not increase the risk of breast cancer. Tibolone however, another form of HRT sometimes prescribed by doctors, does increase breast cancer risk [9]. For some women the benefits of taking HRT may outweigh the risks, hence the decision should always be carefully discussed with the prescribing doctor. To read more about the risks and benefit of HRT, please the NHS website (https://www.nhs.uk/conditions/hormone-replacement-therapy-hrt/risks/) and Cancer Research UK (https://www.cancerresearchuk.org/about-cancer/causes-of-cancer/hormones-and-cancer/does-hormone-replacement-therapy-increase-cancer-risk)

Women who use the combined oral contraceptive pill (containing both progesterone and oestrogen) also have a slightly increased risk of developing breast cancer [11]. However, the additional risk is small compared to other lifestyle factors, such as being overweight or smoking. The risk associated with the combined pill starts to decrease once the pill is stopped, and the additional risk of breast cancer returns to normal after 10 years [11]. When considering risks and benefits of different contraceptive methods, it can be helpful to discuss the options with your doctor.

What are the common symptoms of breast cancer?

The first symptom of breast cancer that most women (or men) notice, is a lump or an area of thickened tissue in their breast. Most breast lumps are not cancerous, but it is important to have any new lumps or changes in the breast tissue checked by your GP. Being aware of the normal appearance and consistency of your own breasts (being ‘breast aware’) is very important when determining the presence of changes; knowing what is ‘normal for you’ will make it much easier to detect any new lumps or changes in your breast tissue.

Other common symptoms of breast cancer are listed below, and you should see your GP if you notice any of the following:

• A change in the size, outline or shape of your breast
• A change in the look or feel of the skin on your breast, such as puckering or dimpling, a rash or redness
• A new lump, swelling, thickening or bumpy area in one breast or armpit that was not there before
• A discharge of fluid from either nipple
• Any change in nipple position, such as your nipple being pulled in or pointing differently
• A rash (like eczema), crusting, scaly or itchy skin or redness on or around your nipple
• Any discomfort or pain in one breast, particularly if it's a new pain and does not go away (although pain is only a symptom of breast cancer in rare cases)

This is not an exhaustive list of breast cancer symptoms. To read more about common symptoms if breast cancer, please see the Cancer Research UK (https://www.cancerresearchuk.org/about-cancer/breast-cancer/symptoms), Breast Cancer Now https://breastcancernow.org/information-support/have-i-got-breast-cancer/signs-symptoms-breast-cancer or the MacMillan Cancer Support https://www.macmillan.org.uk/cancer-information-and-support/breast-cancer/signs-and-symptoms-of-breast-cancer websites. If in any doubt, don’t hesitate to see your GP for a check-up.

It is recommended that all women become familiar with the look and feel of their own breasts, and to check them regularly for new lumps or changes in the tissue. Whilst breast cancer in men is rare, men are also encouraged to do the same.

The NHS Breast-Screening programme recommends the following 5-point plan for being Breast Aware [12]:

1. Know what’s normal for you
2. Look at your breasts and feel them regularly
3. Know what changes to look for
4. Report any changes to a GP without delay
5. Attend routine screening if you’re between 50 and 70 years old

For further information on how to be ‘Breast Aware’, please see the NHS website https://www.nhs.uk/common-health-questions/womens-health/how-should-i-check-my-breasts/ .

In addition, women between the ages of 50 and 70 should attend breast screening every 3 years and should be invited automatically by their GP surgery between the ages of 50 and 53. This involves taking X-rays of the breasts (a mammogram) to look for lumps or changes in breast tissue that are too small to feel. Trans and non-binary people should also attend breast screening depending on their circumstances (further information here https://www.nhs.uk/conditions/breast-screening-mammogram/when-youll-be-invited-and-who-should-go/ ) and should speak to their GP if they believe they should have breast screening but have not been automatically invited. Further general information on the NHS Breast Screening Programme is available here https://www.nhs.uk/conditions/breast-screening-mammogram/.

How is breast cancer diagnosed?

Breast cancer may be diagnosed during routine breast screening or after seeing your GP about worrying symptoms. To confirm the diagnosis, a mammogram (breast X-ray) or ultrasound scan of the breast is usually required. In addition, a small sample of cells from the breast may be taken for laboratory testing, in a procedure called a biopsy. There are several different types of biopsy, but all involve a needle being inserted into the breast to obtain a tissue sample. Cells obtained from a biopsy can be used to determine exactly what type of breast cancer is present, as well as the treatment options available (see next section).

Once a diagnosis of breast cancer is confirmed, further tests such as a chest x-ray, liver ultrasound scan and CT or MRI scan may be needed to help determine the ‘stage’ and ‘grade’ of the cancer. These terms refer to how advanced a cancer is at diagnosis (how far beyond the breast it has spread) and how aggressively the cancer cells are behaving. Additional tests to help guide treatment may also be needed, such as analysing the cancer cells for hormone receptors or their response to specific chemotherapy drugs. To read more about how breast cancer is diagnosed, as well as staging and grading, please see the NHS website here https://www.nhs.uk/conditions/breast-cancer/diagnosis/.

Being diagnosed with breast cancer can be extremely worrying and upsetting for patients and their families, and further support is available through the NHS and dedicated cancer charities such as MacMillan Cancer Support https://www.macmillan.org.uk/cancer-information-and-support/diagnosis

Breast cancer treatment & prognosis

Treatment for breast cancer is different for everyone. Because every cancer is unique, every cancer will be treated slightly differently, depending on factors such as the type of breast cancer, the stage and grade of the cancer, the presence of other medical conditions and the age and overall health of the person being treated. Treatment will also be guided by laboratory analysis of the cancer cells, which determines whether the cancer is responsive to specific hormones or chemotherapy drugs.

In general, treatment options for breast cancer include surgery, radiotherapy, chemotherapy, hormone therapy (for hormone-responsive cancers). These treatments are often used in combination to achieve the best possible outcome. If the cancer is diagnosed at a sufficiently early stage, the aim of treatment will be to cure the cancer (or to enter remission). However, if a cancer is diagnosed at a late stage, where it has already spread far beyond the breast meaning it cannot be cured completely, the aim of treatment will instead be to improve quality of life for the person (palliative treatment), which aims to reduce pain and other unpleasant symptoms.

According to research conducted by Breast Cancer UK between 2002 and 2017, 88% of women diagnosed with breast cancer are predicted to survive for 5 years or more [2]. However, the prognosis (outcome) of a breast cancer diagnosis depends on many factors and cannot always be reliably predicted. One of the most critical factors in determining the outcome of any cancer diagnosis however, is the stage at which it is diagnosed. If a cancer is diagnosed at a very advanced (late) stage, the outcome will generally be much poorer than if it were caught early. For this reason, it is essential that women (and men) check their breasts regularly for symptoms of breast cancer and attend routine screening when eligible, to ensure any cancer present is diagnosed as early as possible. To read more about breast cancer outcomes and what happens after treatment, please see the MacMillan Cancer Support website https://www.macmillan.org.uk/cancer-information-and-support/after-treatment

Breast cancer prevention

In addition to regular self-checking and routine breast screening, changes in lifestyle can help prevent breast cancer. In fact, studies show that around 30% of UK breast cancer cases are preventable through changes in lifestyle, the equivalent of around 17,00 new cases each year [2]. Moreover, these lifestyle changes don’t have to be difficult.

As part of their excellent Prevention Hub https://breastcancerprevention.org.uk/ Breast Cancer UK has compiled a list of top lifestyle tips for preventing breast cancer [13]:

• Diet – eat plenty of fresh fruit and vegetables, buying organic where possible
• Alcohol – reduce your alcohol consumption and have a few alcohol-free days each week
• Physical activity – exercise more, including cardiovascular exercise that makes you sweat
• Chemicals & the environment – reduce your exposure to potentially harmful chemicals where possible. These chemicals may be found in cosmetics, garden and household sprays, plastics and packaged food and drink products. Always check ingredients lists and avoid products containing parabens, triclosan or diethyl phthalate. Avoid plastic packaging which may contain bisphenol-A (BPA) or phthalates (for more on plastics and health, see our dedicated article here https://www.one5.health/post/how-plastics-are-harming-our-health )

To read more about chemicals & environmental factors that can increase your risk of breast cancer, check out Breast Cancer UK’s excellent dedicated resource here https://breastcancerprevention.org.uk/chemicals/ . And for more on everyday lifestyle changes you can make to reduce your risk of breast cancer, please see their Everyday Life guide here https://breastcancerprevention.org.uk/everydaylife/

The bottom line

• Breast cancer is the most commonly diagnosed cancer in the UK and worldwide, affecting millions of women and tens of thousands of men each year.
• Like other many other cancers, breast cancer occurs when abnormal cells proliferate in an uncontrolled manner. These abnormal cells develop due to faults (mutations) in their DNA, which remove the normal biochemical controls on cell growth and division.
• Once breast cancer develops, it may invade neighbouring tissues and body structures or spread to distant parts of the body via the blood or lymphatic systems, which can make the cancer more difficult to treat.
• Whilst breast cancer usually manifests as a tumour in the breast, not all tumours, lumps or tissue changes within the breast are cancerous, and there are several benign breast conditions that manifest in this way.
• There are several different types of breast cancer, which can be broadly categorised and ‘invasive’ or ‘non-invasive’, depending on whether the cancer has spread into tissues other than those in which it originated in the breast. Breast cancer can also be categorised according to the presence of additional receptors for specific hormones on the surface of the cancer cells. These hormones include including oestrogen, progesterone and HER-2, and the response of the breast cancer to these hormones may influence treatment options available.
• Risk factors for developing breast cancer can be broadly divided into non-modifiable and modifiable factors.
• Non-modifiable factors include biological sex, age, family history, genetic predisposition, previous breast cancer and lifelong exposure to oestrogen, amongst others.
• Modifiable risk factors include body weight, diet, physical activity, alcohol consumption, smoking, radiation exposure, use of hormone replacement therapy and the combined oral contraceptive pill, amongst others.
• All women are encouraged to be ‘breast aware’ – to become familiar with the look and feel of their own breasts and to check them regularly for any changes. Women who notice changes in their breasts or worrying symptoms should see their GP without delay.
• Women between the ages of 50 and 70 should also attend routine breast screening every 3 years, which involves taking an x-ray of the breasts (a mammogram)
• Breast cancer may be diagnosed at routine breast screening or after seeing a GP due to concerning symptoms. Confirmation of breast cancer diagnosis usually requires an x-ray (mammogram) or breast ultrasound scan and/or a biopsy. Further testing to determine the cancer’s stage, grade and treatment options may include further scans (X-rays, CT or MRI) or additional biopsies.
• Treatment for breast cancer is different for everybody, but may involve any combination of surgery, radiotherapy, chemotherapy or hormone therapies. The aim of treatment and the treatment options available can be influenced by many factors, including the stage at which the cancer is diagnosed, the type of cancer, the cancer grade and the overall health of the person being treated.
• The prognosis (outcome) of a breast cancer diagnosis cannot always be reliably predicted, but around 88% of women diagnosed in the UK are predicted to survive for 5 years or more. The prognosis of breast cancer can be influenced by many factors, including the stage of the cancer at diagnosis and the treatment options available.
• Up to 30% of breast cancer cases in the UK are preventable through changes in lifestyle. Lifestyle changes that reduce risk of breast cancer include increasing physical activity, reducing alcohol consumption and smoking, eating more fresh vegetables and reducing exposure to harmful chemicals in the environment and everyday domestic products.

Useful links

https://breastcancerprevention.org.uk/

https://www.nhs.uk/conditions/breast-cancer/

https://www.macmillan.org.uk/cancer-awareness/breast-cancer-awareness-month

References

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3. MacMillan Cancer Support, "Types of Breast Cancer," MacMillan, [Online]. Available: https://www.macmillan.org.uk/cancer-information-and-support/breast-cancer/types-of-breast-cancer. [Accessed Oct 2022].
4. Breast Cancer UK, "The Biology of Breast Cancer," Breast Cancer UK, [Online]. Available: https://www.breastcanceruk.org.uk/about-breast-cancer/biology-of-breast-cancer/. [Accessed Oct 2022].
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9. Cancer Research UK, "Does HRT increase cancer risk?," Cancer Research UK, [Online]. Available: https://www.cancerresearchuk.org/about-cancer/causes-of-cancer/hormones-and-cancer/does-hormone-replacement-therapy-increase-cancer-risk. [Accessed Oct 2022].
10. NHS, "Benefits and risks: Hormone replacement therapy," NHS, [Online]. Available: https://www.nhs.uk/conditions/hormone-replacement-therapy-hrt/risks/. [Accessed Oct 2022].
11. Cancer Research UK, "Does the contraceptive pill increase breast cancer risk?," Cnacer Research UK, [Online]. Available: https://www.cancerresearchuk.org/about-cancer/causes-of-cancer/hormones-and-cancer/does-the-contraceptive-pill-increase-cancer-risk?_ga=2.107778754.1916071724.1572528135-1629823779.1569851105. [Accessed Oct 2022].
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