Types of Breast Cancer

Overview and Ductal Carcinoma

The first step in educating yourself about breast cancer is to learn about the different forms of the disease. There are many different types of breast cancer, but the vast majority (over 80%) begins in either the milk ducts or the lobular (milk-producing) tissue. These two types are called ductal carcinoma and lobular carcinoma. Either type, if diagnosed early enough, may be called “in situ”, which means that the cancer has not yet reached the stage where it will invade nearby tissue or lymph nodes and therefore is highly curable. The prognosis (outcome) for the invasive version of either type depends on many factors, such as the stage of the cancer, your age, and your general health.

The other types of breast cancer are less common, sometimes called “special types”, and each has its own specific prognosis.

Ductal Carcinomas

Ductal carcinoma is the most common form of breast cancer. It develops in the ducts that carry the milk from the lobules (milk glands) to the nipple. Ductal carcinomas can be either in situ (DCIS) or invasive breast cancer (IDC).

Ductal Carcinoma In Situ (DCIS)

Ductal carcinoma in situ or DCIS is a non-spreading form of breast cancer. The cells themselves have typical features of cancer, but they are limited to the inside of the milk ducts within the breast. Inside the ducts, the cancer cells divide and multiply, “spreading” up and down the ducts, but they do not invade through the duct walls or move into the blood or lymphatic systems.

Depending on the amount of cancer that is present, and the number of ducts that contain cancer cells, DCIS is described as either localized or diffuse. Treatment options may differ depending on how DCIS is categorized.

If the cancer cells spread up the ducts all the way to the nipple(s), the nipple(s) can appear crusted, scaly and red and cause burning, itching, or ooze a bloody discharge. This condition is known as Paget’s disease of the nipple. (see Paget’s below)

Mammography may or may not show microcalcifications (tiny calcium deposits) in the ducts. DCIS is nearly 100% curable because the cancer is found and treated at such an early stage. If DCIS is not detected, however, the cancer cells may develop the ability to invade the duct walls and nearby tissues. The cancer would then be viewed as invasive ductal carcinoma or IDC.

Invasive Ductal Carcinoma (IDC)

Invasive ductal carcinoma accounts for 70 - 80% of breast cancers. Like DCIS, the cancer begins in the milk ducts but IDC invades the fatty tissues of the breast.

In most cases, breast cancer is slow-growing. Cancer may have been developing for months or years before a lump can be felt. IDC cells, however, will eventually move into nearby breast tissue, and then into the lymphatic channels and travel to nearby lymph nodes (usually the nodes in the armpit area). For those with IDC, it is common to have lymphatic nodes biopsied or removed so they can be examined under a microscope to see if the cancer has spread. It is important to detect and treat IDC before it has had time to metastasize (spread) to the liver, lungs, bones, or other organs.

On mammography, the lump appears opaque with irregular borders and it is common for microcalcifications to be seen. On manual exam, the lump feels hard and immovable and the skin over that area (or over the nipple) may look puckered (retracted). IDC has the ability to spread to other parts of the body (metastasize) by traveling through the blood or lymph systems.

Paget's Disease of the Nipple

Paget’s disease of the breast is an eczema-like change in the skin of the nipple, and 90% of women who have it have an underlying breast cancer. The underlying breast cancer may be a DCIS or invasive breast cancer. This type of breast cancer starts in the milk ducts and spreads to the skin of the nipple and areola (the dark circle around the nipple). Approximately 50% of those who have Paget’s disease will have a palpable (able to be felt with the hand) lump in their breast when they are diagnosed.

Paget's disease is an uncommon form of breast cancer, occurring in only 1% - 2% of all cases of breast cancer. It usually occurs in women in their fifties, but it can occur at a later age. (It can affect men too but this is extremely rare.) If no lump can be felt in the breast tissue and the biopsy shows the growth to be in situ and not invasive, treatment for Paget's disease is very effective.

Lobular Carcinoma

Lobular carcinoma tumors grow in the milk-producing glands of the breast. It is far less common than ductal carcinoma, only about 10% of all breast cancers, but it can present itself in both breasts more often than other types of breast cancer. Lobular carcinoma can be either in situ (LCIS) or invasive breast cancer (ILC).

Lobular Carcinoma In Situ (LCIS)

Lobular carcinoma in situ (also called lobular neoplasia) is a precancerous growth that begins in the milk-producing glands of the breast and does not penetrate through the wall of the lobule(s). Most researchers believe it does not usually become an invasive breast cancer. Women who develop LCIS, however, have a higher risk of developing invasive breast cancer in the same or opposite breast in the future.

Invasive Lobular Carcinoma (ILC)

Invasive lobular carcinoma begins in the milk-producing glands and then moves into the fatty tissue of the breast. Like invasive ductal carcinoma, ILC has the ability to metastasize and spread to other parts of the body. About 5%-10% of breast cancers are invasive lobular carcinomas. It occurs most frequently in women between the ages of 45 and 56.

Invasive lobular carcinoma can be more difficult to detect by mammogram. Instead of a distinct lump with firm borders (like IDC), it normally presents as a diffuse swelling or thickening in the upper outer quadrant (the part of your breast nearer your armpit). Compared to ductal carcinoma, however, lobular carcinoma is associated with a better prognosis.

In about 30% of cases, ILC is found in the opposite breast as well. It is also often found in other parts of the same breast (called multicentric ILC) and is more likely to spread to the uterus and ovaries (ductal carcinomas tend to spread to the bones, liver, and lungs). Most tumors are positive for estrogen and progesterone receptors and so they will respond well to hormonal therapy.
Less Common Types of Breast Cancer

Inflammatory Breast Cancer (IBC)

Inflammatory Breast Cancer (IBC) is a very aggressive type of invasive breast cancer. Some sources say it accounts for less than 1% of all breast cancers but newer estimates figure it to be more like 5%. In IBC, cancer cells block the normal flow of lymph within the breast, causing the skin to appear thick and pitted like the outside of an orange (a symptom called “peau d’orange”). The affected breast(s) may feel warm to the touch and look red. Misdiagnosis can contribute to the poor prognosis – it can be confused with an infection or inflammatory skin condition and often occurs without the typical "lump" most people associate with breast cancer - by delaying proper diagnosis and treatment. Medullary Carcinoma. The tumor in medullary carcinoma is usually a soft, well-defined lump. The well-defined border of the tumor helps prevent the rapid spread of the cancer. Because it is less likely to spread to the lymph nodes, treatment is often more effective against this cancer type than others, leading to a better outcome (prognosis).

Tubular Carcinoma

Tubular carcinoma is rare, accounting for only 3%-4% of all breast cancers. The tumors are usually small, but due to advances in screening techniques, more tubular carcinomas have been detected in recent years. Treatment is more effective for this type of invasive cancer than other forms – with a prognosis of about 80% survival at 5 years.

Mucinous Carcinoma

Mucinous carcinoma, another rare type of invasive breast cancer, also has a good prognosis because it does not easily spread to the lymph nodes. The cancer is formed by mucus-producing cancer cells that spread the disease to surrounding breast tissue. More common in older women, mucinous carcinoma accounts for about 2% of all breast cancers.

Cribriform Carcinoma

This type of invasive breast cancer accounts for only 3% of all breast cancers and has a good prognosis after treatment.

Papillary Carcinoma

Papillary carcinomas account for about 2% of all breast cancers and have a better prognosis than ductal carcinoma.

Phyllodes Tumor

This rare type of breast tumor forms in the connective tissue (stroma) of the breast, unlike the carcinomas that develop in the ducts or lobules. These tumors are usually benign, but in rare cases can be malignant. Malignant phyllodes tumors account for less than 1% of all breast cancers and are responsible for less than 10 breast cancer deaths per year.

Phyllodes tumors do not respond to hormonal therapy and are less likely to respond to other standard breast cancer therapies like chemotherapy and radiation. They are treated surgically by removing the tumor and some of the surrounding healthy tissue or by removing the entire breast (mastectomy).