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Definition of breast cancer:

Cancer that forms in tissues of the breast. The most common type of breast cancer is ductal carcinoma, which begins in the lining of the milk ducts (thin tubes that carry milk from the lobules of the breast to the nipple). Another type of breast cancer is lobular carcinoma, which begins in the lobules (milk glands) of the breast. Invasive breast cancer is breast cancer that has spread from where it began in the breast ducts or lobules to surrounding normal tissue. Breast cancer occurs in both men and women, although male breast cancer is rare.

Breast cancer is a disease in which malignant (cancer) cells form in the tissues of the breast.

The breast is made up of lobes and ducts. Each breast has 15 to 20 sections called lobes, which have many smaller sections called lobules. Lobules end in dozens of tiny bulbs that can make milk. The lobes, lobules, and bulbs are linked by thin tubes called ducts.

Drawing of female breast anatomy showing  the lymph nodes, nipple, areola, chest wall, ribs, muscle, fatty tissue, lobe, ducts, and lobules.

Anatomy of the female breast. The nipple and areola are shown on the outside of the breast. The lymph nodes, lobes, lobules, ducts, and other parts of the inside of the breast are also shown.

Each breast also has blood vessels and lymph vessels. The lymph vessels carry an almost colorless fluid called lymph. Lymph vessels lead to organs called lymph nodes. Lymph nodes are small bean-shaped structures that are found throughout the body. They filter substances in a fluid called lymph and help fight infection and disease. Clusters of lymph nodes are found near the breast in the axilla (under the arm), above the collarbone, and in the chest.

The most common type of breast cancer is ductal carcinoma, which begins in the cells of the ducts. Cancer that begins in the lobes or lobules is called lobular carcinoma and is more often found in both breasts than are other types of breast cancer. Inflammatory breast cancer is an uncommon type of breast cancer in which the breast is warm, red, and swollen.

Health history can affect the risk of developing breast cancer.

Anything that increases your chance of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn't mean that you will not get cancer. Talk with your doctor if you think you may be at risk. Risk factors for breast cancer include the following:

  • Menstruating at an early age.
  • Older age at first birth or never having given birth.
  • A personal history of invasive breast cancer, ductal carcinoma in situ (DCIS), lobular carcinoma in situ (LCIS), or benign (noncancer) breast disease.
  • A family history (first-degree relative, such as mother, daughter, or sister) of breast cancer.
  • Having inherited changes in the BRCA1 or BRCA2 genes.
  • Treatment with radiation therapy to the breast/chest.
  • Having breast tissue that is dense on a mammogram.
  • Taking hormones such as estrogen and progesterone for symptoms of menopause.
  • Having taken the hormone diethylstilbestrol (DES) during pregnancy or being the daughter of a woman who took DES while pregnant.
  • Obesity.
  • Not getting enough exercise.
  • Drinking alcoholic beverages.
  • Being white.

Breast cancer is sometimes caused by inherited gene mutations (changes).

The genes in cells carry the hereditary information that is received from a person’s parents. Hereditary breast cancer makes up about 5% to 10% of all breast cancer. Some mutated genes related to breast cancer are more common in certain ethnic groups.

Women who have certain gene mutations, such as a BRCA1 or BRCA2 mutation, have an increased risk of breast cancer. Also, women who have had breast cancer in one breast have an increased risk of developing breast cancer in the other breast. These women also have an increased risk of ovarian cancer, and may have an increased risk of other cancers. Men who have a mutated gene related to breast cancer also have an increased risk of this disease.

There are tests that can detect (find) mutated genes. These genetic tests are sometimes done for members of families with a high risk of cancer.

Salivary gland type tumours of breast

Breast and salivary glands are both tubulo-acinar exocrine glands sharing similar morphological features; consequently, it is reasonable to expect similarities in pathological processes. Comparing the histological classifications of breast and salivary gland tumours it is evident that the same types of neoplasms can arise at both sites. Salivary gland-like lesions of the breast can be subdivided into two main groups: tumours with myoepithelial differentiation and tumours devoid of or with scanty myoepithelial differentiation.

For more information on salivary gland tumour, please click here.

Adenoid cystic carcinoma of breast 

Adenoid cystic breast cancer is a rare type of invasive ductal breast cancer which accounts for less than 1% of all breast cancers.  Like other types of invasive ductal cancer, adenoid cystic breast cancer begins in the milk duct of the breast before spreading to the tissues around the duct.  When the cells of an adenoid cystic tumor are examined under the microscope, they look like cancer cells more commonly found in the salivary glands and saliva.  These cells are different than those of typical ductal cancers.  

Adenoid cystic tumors are often “triple negative”, meaning that the cells do not express the estrogen receptor, progesterone receptor, or HER2 receptor.  Even when triple negative, adenoid cystic breast cancers are less likely to involve the lymph nodes, are more responsive to treatment, and may have a better prognosis than more common types of invasive ductal cancer. 

Special types of adenocarcinoma of breast

Breast cancers are often a type of carcinoma called adenocarcinoma, which is carcinoma that starts in glandular tissue.

Metaplastic breast cancer

This type of breast cancer is a mixture of two cell types. The cells have started out as one cell type, such as an adenocarcinoma, but some of them have changed into another type of breast cell.

Doctors treat metaplastic cell cancers in the same way as other breast cancers. You may havesurgery, chemotherapy and radiotherapy. But metaplastic breast tumours tend not to be sensitive tohormone therapy.

Metaplastic breast carcinoma (MBC) is a rare type of breast cancer that has basal-like characteristics and is perceived to have poorer prognosis when compared with conventional no specific type/ductal carcinomas (ductal/NST). However, current data on MBC are largely derived from small case series or population-based reports due to the rarity of the condition.

Phyllodes (phylloides) tumours of the breast 

These are rare breast tumors that start in the connective (stromal) tissue of the breast.

Phyllodes tumors are most common in women in their 40s, but women of any age can have them. Women with Li-Fraumeni syndrome (a rare, inherited genetic condition) have an increased risk for phyllodes tumors.

Most phyllodes tumors are benign (not cancer), but about 1 out of 4 of these tumors are malignant (cancer).

Diagnosis

The tumors are usually felt as a painless lump, but some may hurt. They tend to grow quickly and stretch the skin. They’re often hard to tell from fibroadenomas on imaging tests (like an ultrasound or mammogram), or even with certain types of needle biopsies. In most cases, the entire tumor needs to be removed (during an excisional biopsy) to know for sure that it’s a phyllodes tumor, and whether it's malignant or not.

Breast cancer and Pregnancy

Breast cancer is sometimes detected (found) in women who are pregnant or have just given birth.

In women who are pregnant or who have just given birth, breast cancer occurs most often between the ages of 32 and 38. Breast cancer occurs about once in every 3,000 pregnancies.

It may be difficult to detect (find) breast cancer early in pregnant or nursing women, whose breasts are often tender and swollen.

Women who are pregnant, nursing, or have just given birth usually have tender, swollen breasts. This can make small lumps difficult to detect and may lead to delays in diagnosing breast cancer. Because of these delays, cancers are often found at a later stage in these women.

Breast examination should be part of prenatal and postnatal care.

To detect breast cancer, pregnant and nursing women should examine their breasts themselves. Women should also receive clinical breast examinations during their routine prenatal and postnatal examinations.

Possible signs of breast cancer include a lump or change in the breast.

Breast cancer may cause any of the following signs and symptoms. Check with your doctor if you have any of the following problems:

  • A lump or thickening in or near the breast or in the underarm area.
  • A change in the size or shape of the breast.
  • A dimple or puckering in the skin of the breast.
  • A nipple turned inward into the breast.
  • Fluid, other than breast milk, from the nipple, especially if it's bloody.
  • Scaly, red, or swollen skin on the breast, nipple, or areola (the dark area of skin that is around the nipple).
  • Dimples in the breast that look like the skin of an orange, called peau d’orange.

Other conditions that are not breast cancer may cause these same symptoms.

Tests that examine the breasts are used to detect (find) and diagnose breast cancer.

A doctor should be seen if changes in the breast are noticed. The following tests and procedures may be used:

  • Physical exam and history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
  • Clinical breast exam (CBE): An exam of the breast by a doctor or other health professional. The doctor will carefully feel the breasts and under the arms for lumps or anything else that seems unusual.
  • Mammogram: An x-ray of the breast.

Mammography; the left breast is pressed between two plates.  An X-ray machine is used to take pictures of the breast. An inset shows the x-ray film image with an arrow pointed at abnormal tissue.

Mammography. The breast is pressed between two plates. X-rays are used to take pictures of breast tissue.

  • Ultrasound exam: A procedure in which high-energy sound waves (ultrasound) are bounced off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram. The picture can be printed to be looked at later.
  • MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body. This procedure is also called nuclear magnetic resonance imaging (NMRI).
  • Blood chemistry studies: A procedure in which a blood sample is checked to measure the amounts of certain substances released into the blood by organs and tissues in the body. An unusual (higher or lower than normal) amount of a substance can be a sign of disease in the organ or tissue that makes it.
  • Biopsy: The removal of cells or tissues so they can be viewed under a microscope by a pathologist to check for signs of cancer. If a lump in the breast is found, the doctor may need to remove a small piece of the lump. Four types of biopsies are as follows:
    • Excisional biopsy: The removal of an entire lump of tissue.
    • Incisional biopsy: The removal of part of a lump or a sample of tissue.
    • Core biopsy: The removal of tissue using a wide needle.
    • Fine-needle aspiration (FNA) biopsy: The removal of tissue or fluid, using a thin needle.

If cancer is found, tests are done to study the cancer cells.

Decisions about the best treatment are based on the results of these tests. The tests give information about:

  • How quickly the cancer may grow.
  • How likely it is that the cancer will spread through the body.
  • How well certain treatments might work.
  • How likely the cancer is to recur (come back).

Tests include the following:

  • Estrogen and progesterone receptor test: A test to measure the amount of estrogen and progesterone (hormones) receptors in cancer tissue. If there are more estrogen and progesterone receptors than normal, the cancer may grow more quickly. The test results show whether treatment to block estrogen and progesterone may stop the cancer from growing.
  • Human epidermal growth factor type 2 receptor (HER2/neu) test: A laboratory test to measure how many HER2/neu genes there are and how much HER2/neu protein is made in a sample of tissue. If there are more HER2/neu genes or higher levelsof HER2/neu protein than normal, the cancer may grow more quickly and is more likely to spread to other parts of the body. The cancer may be treated with drugs that target the HER2/neu protein, such as trastuzumab and lapatinib.
  • Multigene tests: Tests in which samples of tissue are studied to look at the activity of many genes at the same time. These tests may help predict whether cancer will spread to other parts of the body or recur (come back).
    • Oncotype DX: This test helps predict whether stage I or stage II breast cancer that is estrogen receptor positive and node-negative will spread to other parts of the body. If the risk of the cancer spreading is high, chemotherapy may be given to lower the risk.
    • MammaPrint: This test helps predict whether stage I or stage II breast cancer that is node-negative will spread to other parts of the body. If the risk of the cancer spreading is high, chemotherapy may be given to lower the risk.

Certain factors affect prognosis (chance of recovery) and treatment options.

The prognosis (chance of recovery) and treatment options depend on the following:

  • The stage of the cancer (the size of the tumour and whether it is in the breast only or has spread to lymph nodes or other places in the body).
  • The type of breast cancer.
  • Estrogen receptor and progesterone receptor levels in the tumour tissue.
  • Human epidermal growth factor type 2 receptor (HER2/neu) levels in the tumour tissue.
  • Whether the tumour tissue is triple-negative (cells that do not have estrogen receptors, progesterone receptors, or high levels of HER2/neu).
  • How fast the tumour is growing.
  • How likely the tumour is to recur (come back).
  • A woman’s age, general health, and menopausal status (whether a woman is still having menstrual periods).
  • Whether the cancer has just been diagnosed or has recurred (come back).

For more information on Breast Cancer click here

Information has also been sourced from cancerresearchuk.org, cancer.org, hopkinsmedicine.orgnature.com and ncbi.nlm.nih.gov

This link is to the National Cancer Institute (NCI) cancer website in the United States. There may be references to drugs and clinical trials that are not available here in Australia.

For information courtesy of Cancer Australia, please click here