Breast cancer is a malignant tumor that starts from cells of the breast. A malignant tumor is a group of cancer cells that may invade surrounding tissues or spread (metastasize) to distant areas of the body. The disease occurs almost entirely in women, but men can get it, too. The remainder of this document refers only to breast cancer in women. For information on breast cancer in men, see the American Cancer Society’s document.
Normal Breast Structure
In order to understand breast cancer, it is helpful to have some basic knowledge about the normal structure of the breasts.
The female breast is made up mainly of lobules (milk-producing glands), ducts (tiny tubes that carry the milk from the lobules to the nipple), and stroma (fatty tissue and connective tissue surrounding the ducts and lobules, blood vessels, and lymphatic vessels).
Most breast cancers begin in the cells that line the ducts (ductal cancers); some begin in the cells that line the lobules (lobular cancers), and the rest in other tissues.
The Lymph (Lymphatic) System
The lymph system is important to understand because it is one of the ways in which breast cancers can spread. This system has several parts.
Lymph nodes are small, bean-shaped collections of immune system cells that are connected by lymphatic vessels. Lymphatic vessels are like small veins, except that they carry a clear fluid called lymph (instead of blood) away from the breast. Lymph contains tissue fluid and waste products, as well as immune system cells (cells that are important in fighting infections). Breast cancer cells can enter lymphatic vessels and begin to grow in lymph nodes.
Most lymphatic vessels in the breast connect to lymph nodes under the arm (axillary nodes). Some lymphatic vessels connect to lymph nodes inside the chest (internal mammary nodes) and those either above or below the collarbone (supraclavicular or infraclavicular nodes).
Knowing if the cancer cells have spread to lymph nodes is important because if it has, there is a higher chance that the cells could have also gotten into the bloodstream and spread (metastasized) to other sites in the body. The more lymph nodes that are involved with the breast cancer, the more likely it is that the cancer may be found in other organs as well. This is important to know because it could affect your treatment plan. But not all women with lymph node involvement develop metastases, and it is not unusual for a woman to have negative lymph nodes and later develop metastases.
Benign Breast Lumps
Most breast lumps are not cancerous; that is, they are benign. Still, some need to be sampled and viewed under a microscope to prove they are not cancer.
Fibrocystic Changes
Most lumps turn out to be fibrocystic changes. The term “fibrocystic” refers to fibrosis and cysts. Fibrosis is the formation of fibrous (or scar-like) tissue, and cysts are fluid-filled sacs. Fibrocystic changes can cause breast swelling and pain. This often happens just before a period is about to begin. Your breasts may feel lumpy and, sometimes, you may notice a clear or slightly cloudy nipple discharge.
Other Benign Breast Lumps
Benign breast tumors such as fibroadenomas or intraductal papillomas are abnormal growths, but they are not cancer and cannot spread outside of the breast to other organs. They are not life threatening. Still, some benign breast conditions are important because women with these conditions have a higher risk of developing breast cancer.
For more information see the section, “What Are the Risk Factors for Breast Cancer?” and the American Cancer Society document, Noncancerous Breast Conditions.
Breast Cancer General Terms
It is important to understand some of the key words used to describe breast cancer.
Carcinoma
This is a term used to describe a cancer that begins in the lining layer (epithelial cells) of organs such as the breast. Nearly all breast cancers are carcinomas (either ductal carcinomas or lobular carcinomas).
Adenocarcinoma
An adenocarcinoma is a type of carcinoma that starts in glandular tissue (tissue that makes and secretes a substance). The ducts and lobules of the breast are glandular tissue (they make breast milk), so cancers starting in these areas are sometimes called adenocarcinomas.
Carcinoma In Situ
This term is used for the early stage of cancer, when it is confined to the layer of cells where it began. Specifically in breast cancer, in situ means that the cancer cells remain confined to ducts (ductal carcinoma in situ) or lobules (lobular carcinoma in situ). They have not invaded into deeper tissues in the breast or spread to other organs in the body, and are sometimes referred to as non-invasive breast cancers.
Invasive (Infiltrating) Carcinoma
An invasive cancer is one that has already invaded beyond the layer of cells where it started (as opposed to carcinoma in situ). Most breast cancers are invasive carcinomas — either invasive ductal carcinoma or invasive lobular carcinoma.
Sarcoma
Sarcomas are cancers that start from connective tissues such as fat tissue or blood vessels. Sarcomas of the breast are rare.
Types of Breast Cancers
There are several types of breast cancer, although some of them are quite rare. It is not unusual for a single breast tumor to be a combination of these types and to have a mixture of invasive and in situ cancer.
Ductal Carcinoma In Situ (DCIS)
Ductal carcinoma in situ (also known as intraductal carcinoma) is the most common type of non-invasive breast cancer. DCIS means that the cancer cells are inside the ducts but have not spread through the walls of the ducts into the surrounding breast tissue.
About 1 out of 5 new breast cancer cases will be DCIS. Nearly all women diagnosed at this early stage of breast cancer can be cured. A mammogram is often the best way to find DCIS early.
When DCIS is diagnosed, the pathologist (a doctor specializing in diagnosing disease from tissue samples) will look for an area of dead or dying cancer cells, called tumor necrosis, within the tissue sample. If necrosis is present, the tumor is likely to be more aggressive. The term comedocarcinoma is often used to describe DCIS with necrosis.
Lobular Carcinoma In Situ (LCIS)
Although not a true cancer, LCIS (also called lobular neoplasia) is sometimes classified as a type of non-invasive breast cancer, and this is why it is included here. It begins in the milk-producing glands but does not grow through the wall of the lobules.
Most breast cancer specialists think that LCIS itself does not become an invasive cancer very often, but women with this condition do have a higher risk of developing an invasive breast cancer in the same breast or in the opposite breast. For this reason, women with LCIS should pay close attention to having regular mammograms.
Invasive (or Infiltrating) Ductal Carcinoma (IDC)
This is the most common type of breast cancer. It starts in a milk passage (duct) of the breast, has broken through the wall of the duct, and invaded the fatty tissue of the breast. At this point, it may have the ability to spread (metastasize) to other parts of the body through the lymphatic system and bloodstream. About 8 out of 10 invasive breast cancers are infiltrating ductal carcinomas.
Invasive (or Infiltrating) Lobular Carcinoma (ILC)
Invasive lobular carcinoma starts in the milk-producing glands (lobules). Like IDC, it can spread (metastasize) to other parts of the body. About 1 out of 10 invasive breast cancers are ILCs. Invasive lobular carcinoma may be harder to detect by a mammogram than invasive ductal carcinoma.
Less Common Types of Breast Cancer
Inflammatory breast cancer: This uncommon type of invasive breast cancer accounts for about 1% to 3% of all breast cancers. Usually there is no single lump or tumor. Instead, inflammatory breast cancer (IBC) makes the skin of the breast look red and feel warm and gives the skin a thick, pitted appearance that looks a lot like an orange peel. Doctors now know that these changes are not caused by inflammation or infection, but by cancer cells blocking lymph vessels in the skin. The affected breast may become larger or firmer, tender, or itchy. Inflammatory breast cancer is often mistaken for infection (mastitis) in its early stages. Because there is no defined lump, it may not appear on a mammogram, which may make it even harder to catch it early. It typically has a higher chance of spreading and a worse outlook than typical invasive ductal or lobular cancer.
Mixed tumors: Mixed tumors are those that contain a variety of cell types, such as invasive ductal cancer combined with invasive lobular breast cancer. In this situation, the tumor is treated as if it were an invasive ductal cancer.
Medullary cancer: This special type of infiltrating breast cancer has a rather well-defined, distinct boundary between tumor tissue and normal tissue. It also has some other special features, including the large size of the cancer cells and the presence of immune system cells at the edges of the tumor. Medullary carcinoma accounts for about 3% to 5% of breast cancers. The outlook (prognosis) for this kind of breast cancer is generally better than for the more common types of invasive breast cancer. These are often hard to distinguish from invasive ductal carcinoma. Most cancer specialists think that true medullary cancer is very rare, and that cancers that are called medullary cancer should be treated as the usual invasive ductal breast cancer.
Metaplastic carcinoma: Metaplastic carcinoma (also known as carcinoma with metaplasia) is a very rare variant of invasive ductal cancer. These tumors include cells that are normally not found in the breast, such as cells that look like skin cells (squamous cells) or cells that make bone. These tumors are treated like invasive ductal cancer.
Mucinous carcinoma: Also known as colloid carcinoma, this rare type of invasive breast cancer is formed by mucus-producing cancer cells. The prognosis for mucinous carcinoma is usually better than for the more common types of invasive breast cancer.
Paget disease of the nipple: This type of breast cancer starts in the breast ducts and spreads to the skin of the nipple and then to the areola, the dark circle around the nipple. It is rare, accounting for only about 1% of all cases of breast cancer. The skin of the nipple and areola often appears crusted, scaly, and red, with areas of bleeding or oozing. The woman may notice burning or itching.
Paget disease is almost always associated with either ductal carcinoma in situ (DCIS) or, more often, with infiltrating ductal carcinoma. If no lump can be felt in the breast tissue and the biopsy shows DCIS but no invasive cancer, the prognosis is excellent.
Tubular carcinoma: Tubular carcinomas are another special type of invasive ductal breast carcinoma. It was named tubular because of the way the cells look under the microscope. Tubular carcinomas account for about 2% of all breast cancers and tend to have a better prognosis than infiltrating ductal or lobular carcinomas.
Papillary carcinoma: The cells of these cancers tend to be arranged in small, finger-like projections when viewed under the microscope. These cancers are most often considered to be a subtype of ductal carcinoma in situ (DCIS), and are treated as such. In rare cases they are invasive, in which case they are treated like invasive ductal carcinoma, although the outlook is likely to be better. These cancers make up no more than 1% or 2% of all breast cancers, and they tend to be diagnosed in older women.
Adenoid cystic carcinoma (adenocystic carcinoma): These cancers are so named because they have both glandular (adenoid) and cylinder-like (cystic) features when viewed under the microscope. They make up less than 1% of breast cancers. They rarely spread to the lymph nodes or distant areas, and they tend to have a very good prognosis.
: This very rare breast tumor develops in the stroma (connective tissue) of the breast, in contrast to carcinomas, which develop in the ducts or lobules. Other names for these tumors include phylloides tumor and cystosarcoma phyllodes. These tumors are usually benign but on rare occasions may be malignant.
Benign phyllodes tumors are treated by removing the mass along with a margin of normal breast tissue. A malignant phyllodes tumor is treated by removing it along with a wider margin of normal tissue, or by mastectomy. While surgery is often all that is needed, these cancers may not respond as well to the other treatments used for invasive ductal or lobular breast cancer.
Angiosarcoma: This is a form of cancer that starts from cells that line blood vessels. It rarely occurs in the breasts. When it does, it is usually seen as a complication of radiation to the breast. It tends to develop about 5 to 10 years after radiation treatment. However, this is an extremely rare complication of breast radiation therapy. Angiosarcoma can also occur in the arm of women who develop lymphedema as a result of lymph node surgery or radiation therapy to treat breast cancer. (For information on lymphedema, see the section, “How Is Breast Cancer Treated?”) These cancers tend to grow and spread quickly. Treatment is generally the same as for other sarcomas.
treatment
The main treatments for breast cancer are
- Surgery
- Radiotherapy
- Hormone therapy
- Chemotherapy
- Biological treatments (such as Herceptin)
You may have any of these treatments, or all of them, depending on your situation. It is impossible to generalise about breast cancer treatment because there are so many different sets of circumstances. Your doctor will take many different factors into account when deciding how to treat you. Some of the factors to be considered are
- Whether you have had your menopause
- The type of breast cancer you have
- The size of your breast tumour
- The stage of your breast cancer
- The grade of your cancer cells
- The results of tests on your cancer cells
- Your general health
If you feel strongly about having or not having any particular treatment, do tell your doctor. There may be other options for you. And if you are set on a particular treatment, but your specialist hasn’t suggested it, do ask them. There are almost certainly very good reasons why and your specialist should be able to explain them to you.
Stage and grade
Both of these are important for helping to decide which treatments you need. The stage of your breast cancer means how far it has grown and whether it has spread. Grade means what the cancer cells look like under the microscope. Breast cancers can be
- Low grade or grade 1 (slow growing)
- Intermediate grade or grade 2
- High grade or grade 3 (fast growing)
Low grade cancers tend to grow more slowly than high grade. High grade cancers are more likely to come back after they have first been treated. But these are both rules of thumb, and can only provide a guideline about how any individual cancer will behave. Having said that, doctors will look grade, as well as stage, when deciding which treatments to offer you.
If you have a high grade cancer, your doctor will probably want to give you chemotherapy after surgery, even if there is no sign of cancer spread. This reduces the chance of the cancer coming back.
If you’ve got a cancer that has spread beyond the breast and lymph nodes in the armpit by the time it is diagnosed, your specialist may say that there is no point in putting you through an operation that will only get rid of the cancer in the breast. You may have radiotherapy and chemotherapy instead, combined with other treatments.
Tests on your cancer cells
Your breast cancer cells can be tested to see if they have ‘hormone receptors’ or biological therapy receptors. There are oestrogen receptors and progesterone receptors. You may hear your doctor talk about ‘your oestrogen receptor status’, ‘ER status’ or ‘PR status’. Sometimes, doctors may say you are ‘ER positive’ or ‘ER negative’.
Oestrogen and progesterone are female sex hormones. Many breast cancers are stimulated to grow by the female sex hormones. Now these tests can show whether the receptors are present on the surface of your breast cancer cells. If they are, your cancer is likely to respond to hormone therapy.
A hormone receptor is like a lock on the surface of the cell. The ‘lock’ is the same shape as an oestrogen molecule or a progesterone molecule. The hormone acts like the key to the lock. When it fits into its receptor, the cancer cell is stimulated to grow and divide into 2 new cells. So the breast cancer grows.
If your cancer has oestrogen receptors, then it is also likely to respond to treatment that blocks oestrogen – hormone therapy. Women with breast cancers that are ‘ER positive’ will usually have hormone therapy to help stop their cancer coming back. Current national guidelines for breast cancer treatment recommend that:
- if you are ER positive you should have hormone therapy
- if you are ER negative you should have chemotherapy
You may have hormone therapy if your cancer cells are progesterone receptor positive, even if they are oestrogen receptor negative. In some circumstances, doctors recommend both types of treatment. Younger women who are ER positive will probably have chemotherapy as well as hormone therapy. They will get benefit from both. The chemotherapy can stop the ovaries from working and so cut off the hormone supply to the cancer (see the section below about switching off the ovaries). Older women who have a small, ER negative cancer with a low risk of it coming back might not always have chemotherapy. It depends on how much benefit the doctor thinks it would give. There is more about chemotherapy and hormone therapy further down the page.
You may have heard of another test called Her2. This test is to see if your breast cancer would respond to the biological therapy called trastuzumab (Herceptin). Your breast cancer will only respond to Herceptin if the cells test strongly positive for a protein called Her2. You may also see this written as HER2neu or erbB2. This protein is on the surface of the cells of up to 1 in 4 breast cancers. It is the protein that Herceptin targets. If your breast cancer cells don’t have this protein, Herceptin won’t help you. There is more about Her2 testing in the breast cancer questions section.
Switching off the ovaries
Women who haven’t had their menopause before being diagnosed with breast cancer are still producing oestrogen. If you have an ER positive cancer, then oestrogen can stimulate the breast cancer cells to grow. So doctors recommend treatment to stop oestrogen production. They call this ovarian ablation. There are various ways of doing it. To stop your ovaries working permanently, you may have
- Chemotherapy
- Surgery to remove your ovaries
Chemotherapy is used most often. If you do not want your ovaries to stop working permanently, there is another option that may be suitable. This is to take a drug called an ‘LHRH analogue’ or ‘pituitary downregulator’ for 2 to 3 years. These drugs switch off the ovaries. When you stop having the drug, your ovaries should start to work again. But the nearer you are to the age at which you would naturally have the menopause, the more likely it is that these drugs will switch off your ovaries permanently. There is more about pituitary downregulators in the section on hormone therapy for breast cancer.
All these methods are likely to cause menopausal symptoms. These are often quite intense, as you will have gone into menopause in such a short space of time. The moenpause is immediate if you had surgery or pituitary downregulators.
Researchers are looking into the role of ovarian ablation and chemotherapy for younger women. In May 2007, the journal ‘The Lancet’ published a review of the research into LHRH analogues. The reviewers found that switching off the ovaries with an LHRH analogue is an alternative to chemotherapy for women under 40, with hormone sensitive breast cancer. The advantage of an LHRH analogue compared to other methods of ovarian ablation is that for most women it is temporary. Their periods return 6 to 12 months after finishing treatment and they will become fertile again. For most women, any other menopausal symptoms they’ve had will also stop soon after treatment ends.
There are ongoing trials to find out more about the role of ovarian ablation in treating breast cancer. There is more information about these trials in our what’s new page in this section.
Surgery and radiotherapy
You will probably have some choice about your treatment. Most people begin their treatment with surgery. There are different types of surgery. Depending on the size and position of the tumour, you may be able to have just the cancerous lump removed (lumpectomy) plus several weeks of radiotherapy to the rest of the breast. Or you may prefer the idea of a mastectomy. To help you decide, you may want to consider
- How you feel about having a breast removed
- How you feel about having only part of the breast removed
- How you feel about having radiotherapy
- How quickly you want the treatment to be finished
- How you would cope with travelling to hospital daily for radiotherapy
There are no right and wrong answers to many treatment decisions. Some women feel that they must keep their breast if at all possible. Others feel that once the breast has had cancer in it, they would rather have it removed completely.
Some women feel strongly against radiotherapy. Others welcome it if it means keeping their breast. The most important thing is to take time to find out how you feel and make the right decision for you.
Unfortunately some women do not have much of a choice about surgery. If the cancer is too big, or right in the centre of the breast, the only option may be to remove the whole breast.
Remember – You don’t have to make an ‘on the spot’ decision about treatment. You can say that you need some time to think over your options. Use the time to discuss the issues with family or friends, find out more about the treatments, or just to quietly reflect on your own about how you really feel.
There is more information about these treatments in the CancerHelp UK sections about surgery for breast cancer and radiotherapy for breast cancer.
Breast reconstruction
This is an operation to make a new breast shape after having a breast removed. You should be able to choose whether you would like breast reconstruction or not if you have a mastectomy. There is more about breast reconstruction in CancerHelp UK.
Hormone therapy and chemotherapy
You may have chemotherapy or hormone therapy before or after your surgery and radiotherapy.
Doctors call cancer treatment before surgery ‘neo-adjuvant treatment’, or sometimes ‘primary treatment’. You may have chemotherapy before surgery to try to make the cancer smaller and easier to remove. In older women with locally advanced breast cancer, doctors sometimes use an aromatase inhibitor as a first treatment. These drugs can be very effective at shrinking the cancer in the breast. It will usually be obvious within 6 weeks of starting this treatment how well it is going to work.
Chemotherapy or hormone therapy after surgery is called adjuvant treatment. Your doctor will suggest this because it helps to lower the chance of the cancer coming back. Which treatment you have depends on
- Whether you have had your menopause
- Tests on your cancer cells that help show whether hormone therapy or Herceptin will work for you
- The grade of your cancer cells
- The size of the cancer in the breast and whether it has spread to your lymph nodes
Biological therapy
This is the newest type of cancer treatment. Trastuzumab or Herceptin is a type of biological therapy that can be used to treat breast cancer. If you have early breast cancer, there is now evidence that Herceptin may help to stop your HER2 positive breast cancer from coming back. If you have advanced breast cancer, it may help to keep it under control for longer.
In 2002 NICE approved Herceptin to treat advanced breast cancer. And in August 2006, they approved it for women with early breast cancer. There is information about the NICE guidance on Herceptin in early breast cancer in this section. Herceptin is not suitable for everyone. You may not be able to have it if you have certain heart problems. The links above will take you to more information about who can have treatment with Herceptin.
Swapping notes
When you are first diagnosed with breast cancer, the treatment can sometimes seem very complicated. As you can see there are quite a few different ways of treating it. And it can seem even more confusing if other people you meet are having different treatments. The variation in treatment may be because the other people have different circumstances to you. They may
- Be older or younger than you
- Have a different type of breast cancer
- Have a different stage of breast cancer
- Have a cancer with different hormone receptor status
Don’t be afraid to ask your doctor or nurse if something is puzzling you. This is a complicated area of medicine, even for doctors. And no one will think it strange that you are asking questions about your treatment.
Second opinions
If you do not feel you are getting the treatment you want or need, you can ask for a second opinion. This means going to see another specialist with your test results and X-rays and asking them what treatment they think you should have. It does not usually mean they take over your treatment and care. Just that they discuss with your doctor the right approach to take. Most doctors are quite happy to arrange this for you. It takes time to arrange a second opinion and so your treatment may be delayed for a while.
It is worth discussing your specialists’ approach with them first. Once you have heard why they want to treat you in a certain way you may feel more confident.
