The Breast

A breast is made up of lobules, ducts, fatty tissue, blood vessels, lymph vessels, muscles, and nerves. The lobules are tiny sacs that make milk during breast feeding. There are about one million lobules in each breast. The ducts are tubes that carry the milk from the lobules to the nipple. The fatty tissue surrounds the lobules and ducts to provide support. Lymph vessels carry lymph to lymph nodes in the underarm, above the collarbone, and in the chest. There are also lymph nodes throughout the body. The image below shows the parts of the breast.

Breast overview illustration
Overview of the breast

What is Breast Cancer?

The body is made up of billions of cells that form our tissues and organs. In most organs, cells are replaced on a regular basis, allowing each organ to continue to function normally. During this process, cells that die are replaced by new cells. 

Breast tumors 

Occasionally, cells are replaced by abnormal cells, which grow in an uncontrolled way. As a result, there is an abnormal growth or lump of cells that form a tumor. As they increase in size, benign tumors can present as a lump in the breast. 

There are two kinds of breast tumors: noncancerous tumors (benign) and cancerous tumors (malignant). 

Benign breast tumors are not cancerous. They are made up of tumor cells that do not spread outside the breast in which they appear. 

Malignant breast tumors are cancerous and are made up of cells that can spread from the breast to other parts of the body. Because of their ability to spread and grow in other organs, malignant breast tumors can interfere with normal body functions and be life-threatening. 

Risk factors for breast cancer

There are various risk factors that may contribute to the development of breast cancer. Some have a stronger link to breast cancer than others. The following list describes some of the most significant risk factors for breast cancer. 

  • Age — As a woman gets older, her risk for breast cancer increases.
  • Personal history of breast cancer — Having had breast cancer puts a woman at higher risk for developing it again.
  • Family history of cancer — The risk of breast cancer increases if a woman has a first-degree relative (mother, sister, or daughter) who had breast or ovarian cancer.
  • Genetics — There are inherited genetic mutations that increase the risk of breast cancer. Alterations in the BRCA1 and BRCA2 genes are found in about 5% to 10% of breast cancer cases. Women with alterations in these genes have up to an 85% chance of developing breast cancer in their lifetime.
  • High breast tissue density — The higher the breast tissue density the greater risk for breast cancer. Breast tissue density is generally higher when the breast has more ducts and lobules versus fat.
  • Breast hyperplasia — Hyperplasia is an increase in the growth of cells in a tissue, such as breast tissue. Breast hyperplasia can be detected only by taking a sample of the breast tissue and examining it under a microscope. Breast hyperplasia increases a woman’s chance of developing breast cancer.

There are other risk factors that may contribute to the development of breast cancer. These include:

  • A long lifetime exposure to estrogen — During puberty, estrogen levels dramatically increase. During menopause, estrogen levels decrease. The longer the time the breasts are exposed to estrogen, the higher the risk for developing breast cancer. Therefore, breast cancer risk may be higher in women who started menstruating before 12 years old or in women who went through menopause after 55 years old. Risk may also be higher in women who have taken oral contraceptives or hormone replacement therapy. Since estrogen strengthens bone, women with high bone mass may have a higher risk of breast cancer.
  • Not having children, or having a first child after 30 — These factors may increase a woman’s risk of developing breast cancer, since estrogen levels are lower during pregnancy. Also, not breast feeding may be a risk factor.
  • Radiation exposure — Prior radiation to the chest area increases the risk of breast cancer.
  • Having Ashkenazi Jewish heritage — These women may have an increased risk due to possible inherited gene mutations (such as in the BRCA1 or BRCA2 genes).

Other possible risk factors for breast cancer may include:

  • Being overweight.
  • Not exercising.
  • Drinking alcohol. Drinking one or more alcoholic beverages per day can result in a slight increase in risk.

What Are the Different Types of Breast Cancer?

There are several different types of breast cancer that can be divided into two main categories – noninvasive breast cancers and invasive breast cancers. Noninvasive cancer may also be called carcinoma in situ. Noninvasive breast cancers are confined to the ducts or lobules and they do not spread to surrounding tissues. The two types of noninvasive breast cancers are ductal carcinoma in situ (referred to as DCIS) and lobular carcinoma in situ (referred to as LCIS).

Noninvasive Breast Cancer

There are approximately 58,000 new cases of noninvasive breast cancer in the US each year. Of these, approximately 85% are DCIS. In DCIS, the cancer cells are found only in the milk duct of the breast. If DCIS is not treated, it may progress to invasive cancer. 

In LCIS, the abnormal cells are found only in the lobules of the breast. Unlike DCIS, LCIS is not considered to be a cancer. It is more like a warning sign of increased risk of developing an invasive breast cancer in the same or opposite breast. While LCIS is a risk factor for invasive cancer, it doesn’t actually develop into invasive breast cancer in many women.

Invasive Breast Cancer

There are over 200,000 new cases of invasive breast cancer in women in the US each year. Invasive or infiltrating breast cancers penetrate through normal breast tissue (such as the ducts and lobules) and invade surrounding areas. They are more serious than noninvasive cancers because they can spread to other parts of the body, such as the bones, liver, lungs, and brain. 

There are several kinds of invasive breast cancers. The most common type is invasive ductal carcinoma, which appears in the ducts and accounts for about 80% of all breast cancer cases. There are differences in the various types of invasive breast cancer, but the treatment options are similar for all of them. For more information, please see the Treatment Options section. 

What are the Signs and Symptoms of Breast Cancer?

In the early stages, breast cancer may not be painful and there may be no symptoms at all. As the cancer grows you may start to notice changes in the breast or underarm such as a lump.

These signs and symptoms do not necessarily mean that you have breast cancer. However, you should tell your doctor about any lump or any changes in the skin of the breast, nipple, or areola (the round area of dark-colored skin around the nipple).

The earlier you detect breast cancer, the sooner it can be treated and the better it responds to therapy. Because there may be no symptoms of breast cancer in its early stages, the American Cancer Society (ACS) suggests other techniques and tests for early detection. 

Signs and Symptoms of Breast Cancer

  • Lumps. Breast cancer lumps vary and may be hard or soft and have rounded or uneven edges.
  • Swelling of part of the breast.
  • Skin irritation or dimpling.
  • Nipple pain or the nipple turning inward.
  • Redness or scaliness of the nipple or breast skin.
  • Nipple discharge other than breast milk. A lump in the underarm area.

If you are experiencing signs or symptoms of this issue, or have questions, you can schedule an appointment with us at our Baldwin Park office in Orlando, FL.

The Stages of Breast Cancer

Early Breast Cancer

The term “early breast cancer” refers to stages of breast cancer labeled 0, I, II, and IIIA.

Stage 0

Cancer cells are present in either the lining of a breast lobule or a duct, but
they have not spread to the surrounding fatty tissue. This stage is also called
ductal carcinoma in situ, or DCIS.

Stage I

Cancer has spread from the lobules or ducts to nearby tissue in the breast. At this stage and beyond, breast cancer is considered to be invasive. The tumor is 2 cm or less in diameter (approximately 1 inch or less); the cancer has not spread to the lymph nodes.

Stage II

In this stage, the tumor can range from 2 cm to less than 5 cm in diameter (approximately 1 to 2 inches); sometimes cancer may have spread to the lymph nodes.

Stage IIIA

In this stage, the tumor is 5 cm or greater in diameter (approximately 2 inches or greater); or the tumor may be of any size where cancer cells have grown extensively into axillary (underarm) lymph nodes.

Advanced stages of breast cancer

The term “advanced breast cancer” refers to stages of breast cancer labeled IIIB and IV.

Stage IIIB

Known as locally advanced cancer; tumor may be of any size, but has spread into the skin of the breast or tissues of the chest wall.

Stage IV

Known as metastatic; cancer has spread from the breast to other parts of the body, such as bone, liver, lung, or brain.

How is Breast Cancer Treated?

While there are several different ways to treat breast cancer, all options can be divided into two categories: local therapy or systemic therapy.

Local therapy is directed only at the cancer cells in the breast area. Surgery and radiation are the two local therapies for treating breast cancer. Local therapies only treat a specific area of the body and they are often used in combination with systemic therapy. Systemic therapy may be used to help reduce the risk for recurrence after local therapy is completed.

Systemic therapy is the use of medications that travel in the bloodstream to affect or treat cancer cells. Systemic therapies are often used in combination with local therapy in early breast cancer. It may also be used alone in more advanced stages when cancer has spread to other parts of the body. Hormonal treatment, chemotherapy, and novel targeted therapy are the different types of systemic therapies used to treat breast cancer. 


Below are some of the breast cancer organizations and Web sites that offer more information, as well as support and assistance for you, your family, and friends. 

This list of resources is provided merely as a convenience. AstraZeneca takes no responsibility for the content of, or services provided by, these resources and makes no representation as to the accuracy or completeness of any information provided. AstraZeneca shall have no liability for any damages or injuries of any kind arising from the information provided.

Click on “Support and Community”

American Society of Clinical Oncology
Click on “Community Center”

The National Coalition for Cancer Survivorship
Click on “Listen” to access “Cancer Survival Toolbox”

Y Me National Breast Cancer Organization
Click on “I’m looking for support and services”

Treatment Options

American Cancer Society
Click on treatment options or search for hormonal treatment
Read the latest information about early-stage breast cancer and treatment options

Staying Committed to Your Treatment
Tips for coping with side effects, health insurance, and communicating with your doctor
Tips to help you remember to take your medication

These Web sites and many more can be accessed through

If you are experiencing signs or symptoms of this issue, or have questions, you can schedule an appointment with us at our Baldwin Park office in Orlando, FL.


  • Distant recurrence: the recurrence of breast cancer in parts of the body other than the breast. It may develop in lymph nodes, lung, liver, bone, or brain.
  • Ducts: small tubes in the breast that carry milk from the lobules to the nipple during breastfeeding.
  • Estrogen: a hormone produced by the ovaries, adrenal glands, and other tissues. It is responsible for the development of female sex characteristics and it is important in menstruation and fertility. Estrogen may also cause the growth of some breast cancers (those that are determined to be estrogen-receptor positive).
  • Histology: refers to the smallest parts and characteristics of cells and tissues.
  • Hormonal treatment: a way of treating breast cancer through the use of drugs that block the effect of estrogen or decrease estrogen levels in the body. It is different from hormone replacement therapy.
  • Hormone replacement therapy: treatment that provides estrogen to women to help ease the symptoms of menopause.
  • Hyperplasia: an increase in the number of normal cells in a tissue or organ.
  • Invasive breast cancer: cancer that penetrates ducts and lobules and other surrounding tissues.
  • Lobule: a small sac in the breast that makes breast milk during breastfeeding.
  • Local recurrence: the return of breast cancer in the breast where the original tumor developed or in the skin or underlying tissue where the breast was removed.
  • Local therapy: a treatment that is directed only at the area where the cancer is, such as surgery or radiation to the breast in breast cancer.
  • Lymph: a clear fluid collected from tissues around the body and returned to the blood by the lymphatic system.
  • Lymph nodes: small bean-shaped structures scattered along the vessels of the lymphatic system. The lymph nodes may trap cancer cells that travel through the lymphatic system.
  • Lymph or lymphatic vessels: a series of tubes in the body that carry lymph.
  • Malignant: a tumor that is cancerous and may spread to other parts of the body and may be life-threatening.
  • Menopause: a stage in a woman’s life when menstruation stops and the ovaries stop producing eggs and estrogen.
  • Metastasis: a tumor or growth of cells in a part of the body that is different from where the original or primary tumor was located. Metastases is the plural for metastasis.
  • Metastasize: cancer cells breaking off from their primary site and spreading to nearby or distant areas through the blood and/or lymph.
  • Noninvasive breast cancer/Carcinoma in situ: cancer within the ducts and lobules that does not spread to any other surrounding tissues.
  • Radiation and radiotherapy: the use of x-rays to treat cancer.
  • Recurrence: the return of signs or symptoms of a disease after having had an original cancer removed completely.
  • Regional recurrence: the recurrence of breast cancer in the lymph nodes near the affected breast after having had the original cancer removed completely.
  • Systemic therapy: treatments that travel through the bloodstream to affect or treat cells throughout the body. In breast cancer, systemic therapies may include chemotherapy and hormone treatment.
  • Total mastectomy (mas-tek’to-mee): excision of the entire breast.
  • Tumor: abnormal tissue that grows more quickly than normal, due to cellular proliferation. The growth continues after the initial cause of the new growth has ended.

This information is a brief summary of the education guidebook called Understanding Breast Cancer and Treatment Options: A Guidebook for Patients and Caregivers. To view the entire document, please click here.

Source: AstraZeneca