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What is breast cancer?1

Cancer starts when cells begin to grow out of control. Breast cancer is cancer that originates in the breast, and can start in one or both breasts. Breast cancer occurs almost entirely in women.1

Know the facts about breast cancer1

Breast cancer is the most common cancer in women and the second most common cancer overall. Finding a lump in your breast does not mean you have breast cancer, most breast lumps are benign and not cancer (malignant). Non-cancer breast tumors are abnormal growths, but they do not spread outside of the breast.1,2,3

The Breast


The nipple is the opening in the skin of the breast where the ducts come together and turn into larger ducts so the milk can leave the breast. The nipple is surrounded by slightly darker thicker skin called the areola. A less common type of breast cancer called Paget disease of the breast can start in the nipple.


Ducts are small canals that come out from the lobules and carry the milk to the nipple. This is the most common place for breast cancer to start and are called ductal cancers.


The fat and connective tissue (stroma) surround the ducts and lobules and help keep them in place. Phyllodes tumor can start in the stroma.

Blood vessels and lymph vessels

Blood vessels and lymph vessels are also found in each breast. Angiosarcoma can start in the lining of these vessels.


Lobules are the glands that make breast milk. Cancers that start here are called lobular cancers.

Signs and Symptoms of breast cancer2

Knowing how your breasts normally look and feel is an important part of your breast health. Having regular screening tests for breast cancer is important, asfor you to know what your breasts normally look and feel like, so you’ll be aware of any changes in your breasts. The most common symptom of breast cancer is a new lump or mass. A painless, hard mass that has irregular edges is more likely to be cancer. Possible symptoms include:

  • Swelling of all or part of a breast

  • Skin dimpling

  • Breast or nipple pain

  • Nipple retraction

  • Nipple or breast skin that is red, dry, flaking, or thickened

  • Nipple discharge

  • Swollen lymph nodes under the arm or near the collar bone

Many of these symptoms can also be caused by benign (non-cancerous) breast conditions. Still, it’s important to have any new breast mass, lump, or other change checked by an experienced health care professional so the cause can be found and treated, if needed.

Knowing what to look for does not take the place of having regular screening for breast cancer. Screening mammography can often help find breast cancer early, before any symptoms appear. Finding breast cancer early gives you a better chance of successful treatment.

Types of breast cancer1

Ductal or lobular carcinoma

Most breast cancers are carcinomas, which are tumors that start in the epithelial cells that line organs and tissues throughout the body. When carcinomas form in the breast, they are usually a more specific type called adenocarcinoma, which starts in cells in the ducts or the lobule.

In situ vs. invasive breast cancers

The type of breast cancer can also refer to whether the cancer has spread or not. In situ breast cancer (ductal carcinoma in situ or DCIS) is a pre-cancer that starts in a milk duct and has not grown into the rest of the breast tissue. The term invasive breast cancer is used to describe any type of breast cancer that has spread into the surrounding breast tissue.

Ductal carcinoma in situ (DCIS)

Also called intraductal carcinoma or stage 0 breast cancer, a noninvasive or preinvasive breast cancer. The cells that line the ducts have changed to cancer cells but they have not spread through the walls of the ducts into the nearby breast tissue. Because DCIS hasn’t spread into the breast tissue around it, it can’t spread (metastasize) beyond the breast to other parts of the body. Nearly all women with this early stage of breast cancer can be cured.

Treating DCIS

A woman with DCIS can choose between breast-conserving surgery (BCS) and simple mastectomy. Radiation is usually given after BCS. Tamoxifen or an aromatase inhibitor after surgery might also be an option if the DCIS is hormone-receptor positive.

Invasive breast cancer (ILC or IDC)

Breast cancers that have spread into surrounding breast tissue are known as invasive breast cancers. Most breast cancers are invasive, but there are different types of invasive breast cancer. The two most common are invasive ductal carcinoma and invasive lobular carcinoma.

Invasive ductal carcinoma (IDC)

IDC starts in the cells that line a milk duct in the breast. From there, the cancer breaks through the wall of the duct, and grows into the nearby breast tissues. At this point, it may be able to spread (metastasize) to other parts of the body through the lymph system and bloodstream.

Invasive lobular carcinoma (ILC)

ILC starts in the breast glands that make milk (lobules). Like IDC, it can spread (metastasize) to other parts of the body. Invasive lobular carcinoma may be harder to detect on physical exam and imaging, like mammograms, than invasive ductal carcinoma. And compared to other kinds of invasive carcinoma, it is more likely to affect both breasts.

Treating Invasive breast cancer (ILC or IDC)

Treatment of invasive breast cancer depends on how advanced the cancer is (the stage of the cancer) and other factors. Most women will have some type of surgery to remove the tumor. Depending on the type of breast cancer and how advanced it is, you might need other types of treatment as well, either before or after surgery, or sometimes both.

Special types of invasive breast cancers

Some invasive breast cancers have special features or develop in different ways that influence their treatment and outlook. These cancers are less common but can be more serious than other types of breast cancer.

Triple-negative breast cancer

Triple-negative breast cancer is an aggressive type of invasive breast cancer in which the cancer cells don’t have estrogen or progesterone receptors (ER or PR) and also don’t make the protein called HER2. It tends to grow and spread faster, has fewer treatment options, and tends to have a worse prognosis.

Treating Triple-negative breast cancer

Chemotherapy might be given first to shrink a large tumor, followed by surgery. Chemotherapy is recommended after surgery. Radiation might also be an option. When the cancer has spread to other parts of the body (stage IV), platinum chemotherapy, targeted drugs like a PARP inhibitor or antibody-drug conjugate, or immunotherapy with chemotherapy might be considered.

Inflammatory breast cancer

Inflammatory breast cancer is an aggressive type of invasive breast cancer in which cancer cells block lymph vessels in the skin, causing the breast to look “inflamed.”

Treating Inflammatory breast cancer

In cancer that has not spread outside the breast (stage III) chemotherapy is tried first to shrink the tumor, followed by surgery. Radiation and other treatments, like more chemotherapy or targeted drug therapy, are given after surgery. IBC that has spread to other parts of the body (stage IV) may be treated with chemotherapy, hormone therapy and targeted drugs.

Less common types of breast cancer

There are other types of breast cancers that start to grow in other types of cells in the breast. These cancers are much less common, and sometimes need different types of treatment.

Paget disease of the breast

Paget disease is a rare type of breast cancer involving the skin of the nipple and the areola, usually affecting only one breast. In 80-90% of cases, it’s usually found along with either ductal carcinoma in situ (DCIS) or infiltrating ductal carcinoma (invasive breast cancer).

Treating Paget disease of the breast

Paget disease can be treated by removing the entire breast (mastectomy) or breastconserving surgery (BCS) followed by whole-breast radiation therapy. If BCS is done, the entire nipple and areola area also needs to be removed. If invasive cancer is found, the lymph nodes under the arm will be checked for cancer. If no lump is felt in the breast tissue, and your biopsy results show the cancer has not spread within the breast tissue, the outlook is excellent. If the cancer has spread within the breast tissue (is invasive), the cancer will be staged and treated like invasive ductal carcinoma.

Angiosarcoma of the breast

Angiosarcoma is a rare cancer that starts in cells that line blood vessels or lymph vessels. It can involve the breast tissue or the skin of the breast. Many times it’s a complication of previous radiation treatment to the breast. It can happen 8-10 years after getting radiation treatment to the breast.

Treating Angiosarcoma of the breast

Angiosarcomas tend to grow and spread quickly. Treatment includes surgery to remove the breast (mastectomy). The axillary lymph nodes are not removed. Radiation might be given in certain cases of angiosarcomas.

Phyllodes tumor of the breast

Phyllodes tumors develop in the connective tissue (stroma) of the breast, in contrast to carcinomas, which develop in the ducts or lobules. Most are benign. Most common in women in their 40s, and in woman with Li-Fraumeni syndrome. Phyllodes tumors are often divided into 3 groups. Benign (non-cancerous) tumors account for more than half of all phyllodes tumors and least likely to grow quickly or to spread. Borderline tumors have features in between benign and malignant (cancerous) tumors. Malignant (cancerous) tumors tend to grow the fastest and are the most likely to spread or to come back after treatment.

Treating Phyllodes tumor of the breast

Phyllodes tumors typically need to be removed completely with surgery. If the tumor is benign an excisional biopsy might be all that is needed, as long as the tumor was removed completely. If the tumor is borderline or malignant, a wider margin usually needs to be removed as well. This might be done with breast conserving surgery (part of the breast is removed). The entire breast might also be removed with a mastectomy. Radiation therapy might be given to the area after surgery. Malignant phyllodes tumors are different from the more common types of breast cancer. They are less likely to respond to some of the treatments commonly used for breast cancer, such as the hormone therapy or chemotherapy drugs normally used for breast cancer. Phyllodes tumors that have spread to other parts of the body are often treated more like sarcomas (soft-tissue cancers).

Prevention of breast cancer1

Studies continue to look at whether certain levels of physical activity, losing weight, or eating certain foods, groups of foods, or types of diets might help lower breast cancer risk. Hormonal medicines have already been shown to help lower breast cancer risk for women at higher risk. Clinical trials are looking at whether some non-hormonal drugs might lower breast cancer risk, such as drugs used to treat blood or bone marrow disorders. Vaccines might also help prevent certain types of breast cancer. Strategies that may help reduce a patient’s risk of breast cancer include avoiding postmenopausal obesity, engaging in regular physical activity and minimizing alcohol intake.

Risk Factors of breast cancer1,3

Studies continue to look at how certain lifestyle factors, habits, and other environmental factors, as well as inherited gene changes, might affect breast cancer risk. The effects of physical activity, weight gain or loss, and diet on breast cancer risk are being observed. Some breast cancers run in families, but many of the gene mutations are not yet known. Studies are focusing on the best use of genetic testing for inherited breast cancer gene mutations and exploring how common gene variants may affect breast cancer risk. Environmental causes of breast cancer have also received more attention in recent years.

  • Inheritance - Family history of breast and/or ovarian cancer, especially in a first-degree relative

  • Medical History - Personal history of breast cancer, dense breast tissue, high levels of certain hormones after menopause

  • Reproductive - Full-term pregnancy, current or recent use of oral contraceptives and use of menopausal hormones

  • Lifestyle - Modifiable risk factors includes being overweight / obese after menopause, maintaining a healthy weight
    alcohol consumption, limiting intake of alcohol. Physical inactivity, adopting a active lifestyle. Smoking, not smoking
    decreases risk

  • Environmental - High-dose radiation therapy to the chest, night-shift work (due to disruptions to circadian rhythm)

Treatment 4

Treating Breast Cancer

If you’ve been diagnosed with breast cancer, your cancer care team will discuss your treatment options with you. It’s important that you think carefully about each of your choices and weigh the benefits of each treatment option.

Local treatments

Treatments like surgery and radiation, are local, meaning they treat the tumor without affecting the rest of the body. Most women with breast cancer will have some type of surgery to remove the tumor. Depending on the type of breast cancer and how advanced it is, you might need other types of treatment as well, either before or after surgery, or sometimes both.

  • Surgery for Breast Cancer

  • Radiation for Breast Cancer

Systemic treatments

Drugs used to treat breast cancer are considered systemic therapies because they can reach cancer cells almost anywhere in the body. Given by mouth, injected into a muscle, or put directly into the bloodstream. Depending on the type of breast cancer, different types of drug treatment might be used, including:

  • Chemotherapy for Breast Cancer

  • Hormone Therapy for Breast Cancer

  • Targeted Drug Therapy for Breast Cancer

  • Immunotherapy for Breast Cancer

Related Content 

Renal Cancer


  1. About Breast Cancer. American Cancer Society. [Internet]. Available from: Accessed: 20/08/2023.
  2. Breast Cancer Signs and Symptoms. American Cancer Society. [Internet]. Available from: html Accessed: 20/08/2023.
  3. Lifestyle-related Breast Cancer Risk Factors. American Cancer Society. [Internet]. and-prevention/lifestyle-related-breast-cancer-risk-factors.html. Accessed: 20/08/2023.
  4. Treating Breast Cancer. American Cancer Society. [Internet]. Available from: cancer/treatment.html. Accessed: 20/08/2023.


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