IDC — Invasive Ductal Carcinoma

Invasive ductal carcinoma (IDC), sometimes called infiltrating ductal carcinoma, is the most common type of breast cancer. About 80% of all breast cancers are invasive ductal carcinomas.

Invasive means that the cancer has “invaded” or spread to the surrounding breast tissues. Ductal means that the cancer began in the milk ducts, which are the “pipes” that carry milk from the milk-producing lobules to the nipple. Carcinoma refers to any cancer that begins in the skin or other tissues that cover internal organs — such as breast tissue. All together, “invasive ductal carcinoma” refers to cancer that has broken through the wall of the milk duct and begun to invade the tissues of the breast. Over time, invasive ductal carcinoma can spread to the lymph nodes and possibly to other areas of the body.

Normal breast with invasive ductal carcinoma (IDC) in an enlarged cross-section of the duct
Breast profile:
A Ducts
B Lobules
C Dilated section of duct to hold milk
D Nipple
E Fat
F Pectoralis major muscle
G Chest wall/rib cage
Enlargement
A Normal duct cell
B Ductal cancer cells breaking through the basement membrane.
C Basement membrane



According to the American Cancer Society, more than 180,000 women in the United States find out they have invasive breast cancer each year. Most of them are diagnosed with invasive ductal carcinoma.

Although invasive ductal carcinoma can affect women at any age, it is more common as women grow older. According to the American Cancer Society, about two-thirds of women are 55 or older when they are diagnosed with an invasive breast cancer. Invasive ductal carcinoma also affects men.

DCIS — Ductal Carcinoma In Situ

Ductal carcinoma in situ (DCIS) is the most common type of non-invasive breast cancer. Ductal means that the cancer starts inside the milk ducts, carcinoma refers to any cancer that begins in the skin or other tissues (including breast tissue) that cover or line the internal organs, and in situ means "in its original place." DCIS is called "non-invasive" because it hasn’t spread beyond the milk duct into any normal surrounding breast tissue. DCIS isn’t life-threatening, but having DCIS can increase the risk of developing an invasive breast cancer later on.

When you have had DCIS, you are at higher risk for the cancer coming back or for developing a new breast cancer than a person who has never had breast cancer before. Most recurrences happen within the 5 to 10 years after initial diagnosis. The chances of a recurrence are under 30%.

Women who have breast-conserving surgery (lumpectomy) for DCIS without radiation therapy have about a 25% to 30% chance of having a recurrence at some point in the future. Including radiation therapy in the treatment plan after surgery drops the risk of recurrence to about 15%. Learn what additional steps you can take to lower your risk of a new breast cancer diagnosis or a recurrence in the Lower Your Risk section. If breast cancer does come back after earlier DCIS treatment, the recurrence is non-invasive (DCIS again) about half the time and invasive about half the time. (DCIS itself is NOT invasive.)

According to the American Cancer Society, about 60,000 cases of DCIS are diagnosed in the United States each year, accounting for about 1 out of every 5 new breast cancer cases.

There are two main reasons this number is so large and has been increasing over time:

People are living much longer lives. As we grow older, our risk of breast cancer increases.
More people are getting mammograms, and the quality of the mammograms has improved. With better screening, more cancers are being spotted early.
On the following pages you can learn about:

Types of Breast Cancer

Breast cancer can begin in different areas of the breast — the ducts, the lobules, or in some cases, the tissue in between. In this section, you can learn about the different types of breast cancer, including non-invasive, invasive, recurrent, and metastatic breast cancers, as well as the intrinsic or molecular subtypes of breast cancer. You can also read about breast cancer in men.

• DCIS — Ductal Carcinoma In Situ
• IDC — Invasive Ductal Carcinoma
• IDC Type: Tubular Carcinoma of the Breast
• IDC Type: Medullary Carcinoma of the Breast
• IDC Type: Mucinous Carcinoma of the Breast
• IDC Type: Papillary Carcinoma of the Breast
• IDC Type: Cribriform Carcinoma of the Breast
• ILC — Invasive Lobular Carcinoma
• Inflammatory Breast Cancer
• LCIS — Lobular Carcinoma In Situ
• Male Breast Cancer
• Molecular Subtypes of Breast Cancer
• Paget's Disease of the Nipple
• Phyllodes Tumors of the Breast
• Recurrent & Metastatic Breast Cancer

Symptoms of Breast Cancer

Initially, breast cancer may not cause any symptoms. A lump may be too small for you to feel or to cause any unusual changes you can notice on your own. Often, an abnormal area turns up on a screening mammogram (X-ray of the breast), which leads to further testing.

In some cases, however, the first sign of breast cancer is a new lump or mass in the breast that you or your doctor can feel. A lump that is painless, hard, and has uneven edges is more likely to be cancer. But sometimes cancers can be tender, soft, and rounded. So it's important to have anything unusual checked by your doctor.

According to the American Cancer Society, any of the following unusual changes in the breast can be a symptom of breast cancer:

swelling of all or part of the breast
skin irritation or dimpling
breast pain
nipple pain or the nipple turning inward
redness, scaliness, or thickening of the nipple or breast skin
a nipple discharge other than breast milk
a lump in the underarm area
These changes also can be signs of less serious conditions that are not cancerous, such as an infection or a cyst. It’s important to get any breast changes checked out promptly by a doctor.

In the following posts , you can learn about:

Understanding Breast Cancer

How breast cancer happens, how it progresses, the stages, and a look at risk factors.
Screening and Testing
The tests used for screening, diagnosis, and monitoring, including mammograms, ultrasound, MRI, CAT scans, PET scans, and more.

Types of Breast Cancer

The different types of breast cancer, including ductal carcinoma in situ (DCIS), invasive ductal carcinoma (IDC), invasive lobular carcinoma (ILC), inflammatory breast cancer, male breast cancer, recurrent breast cancer, metastatic breast cancer, and more.

Your Diagnosis

The characteristics of the cancer — featured on your pathology report — that might affect your treatment plan, including size, stage, lymph node status, hormone receptor status, and more.

Breast Cancer Risk and Risk Factors

You may be familiar with the statistic that says 1 in 8 women will develop invasive breast cancer. Many people misinterpret this to mean that, on any given day, they and the women they know have a 1-in-8 risk of developing the disease. That’s simply not true.

In reality, about 1 in 8 women in the United States — 12%, or about 12 out of every 100 — can expect to develop breast cancer over the course of an entire lifetime. In the U.S., an average lifetime is about 80 years. So, it’s more accurate to say that 1 in 8 women in the U.S. who reach the age of 80 can expect to develop breast cancer. In each decade of life, the risk of getting breast cancer is actually lower than 12% for most women.

People tend to have very different ways of viewing risk. For you, a 1-in-8 lifetime risk may seem like a high likelihood of getting breast cancer. Or you may turn this around and reason that there is a 7-in-8, or 87.5%, chance you will never get breast cancer, even if you live to age 80. How you view risk often depends on your individual situation — for example, whether you or many women you know have had breast cancer, or you have reason to believe you are at higher-than-normal risk for the disease — and your usual way of looking at the world.

Even though studies have found that women have a 12% lifetime risk of developing breast cancer, your individual risk may be higher or lower than that. Individual risk is affected by many different factors, such as family history, reproductive history, lifestyle, environment, and others.

What Is Breast Cancer?

Breast cancer is an uncontrolled growth of breast cells. To better understand breast cancer, it helps to understand how any cancer can develop.

Cancer occurs as a result of mutations, or abnormal changes, in the genes responsible for regulating the growth of cells and keeping them healthy. The genes are in each cell’s nucleus, which acts as the “control room” of each cell. Normally, the cells in our bodies replace themselves through an orderly process of cell growth: healthy new cells take over as old ones die out. But over time, mutations can “turn on” certain genes and “turn off” others in a cell. That changed cell gains the ability to keep dividing without control or order, producing more cells just like it and forming a tumor.

A tumor can be benign (not dangerous to health) or malignant (has the potential to be dangerous). Benign tumors are not considered cancerous: their cells are close to normal in appearance, they grow slowly, and they do not invade nearby tissues or spread to other parts of the body. Malignant tumors are cancerous. Left unchecked, malignant cells eventually can spread beyond the original tumor to other parts of the body.

The term “breast cancer” refers to a malignant tumor that has developed from cells in the breast. Usually breast cancer either begins in the cells of the lobules, which are the milk-producing glands, or the ducts, the passages that drain milk from the lobules to the nipple. Less commonly, breast cancer can begin in the stromal tissues, which include the fatty and fibrous connective tissues of the breast.

Breast profile:
A Ducts
B Lobules
C Dilated section of duct to hold milk
D Nipple
E Fat
F Pectoralis major muscle
G Chest wall/rib cage

Enlargement
A Normal duct cells
B Basement membrane
C Lumen (center of duct)

Over time, cancer cells can invade nearby healthy breast tissue and make their way into the underarm lymph nodes, small organs that filter out foreign substances in the body. If cancer cells get into the lymph nodes, they then have a pathway into other parts of the body. The breast cancer’s stage refers to how far the cancer cells have spread beyond the original tumor (see the Stages of breast cancer table for more information).

Breast cancer is always caused by a genetic abnormality (a “mistake” in the genetic material). However, only 5-10% of cancers are due to an abnormality inherited from your mother or father. Instead, 85-90% of breast cancers are due to genetic abnormalities that happen as a result of the aging process and the “wear and tear” of life in general.

There are steps every person can take to help the body stay as healthy as possible, such as eating a balanced diet, maintaining a healthy weight, not smoking, limiting alcohol, and exercising regularly . While these may have some impact on your risk of getting breast cancer, they cannot eliminate the risk.

Developing breast cancer is not your or anyone's fault. Feeling guilty, or telling yourself that breast cancer happened because of something you or anyone else did, is not productive.

Stages of breast cancer

Stage	Definition
Stage 0	Cancer cells remain inside the breast duct, without invasion into normal adjacent breast tissue.
Stage IA	The tumor measures up to 2 cm AND the cancer has not spread outside the breast; no lymph nodes are involved
Stage IB	There is no tumor in the breast; instead, small groups of cancer cells -- larger than 0.2 millimeter but not larger than 2 millimeters – are found in the lymph nodes OR there is a tumor in the breast that is no larger than 2 centimeters, and there are small groups of cancer cells – larger than 0.2 millimeter but not larger than 2 millimeters – in the lymph nodes.
Stage IIA	No tumor can be found in the breast, but cancer cells are found in the axillary lymph nodes (the lymph nodes under the arm) OR the tumor measures 2 centimeters or smaller and has spread to the axillary lymph nodes OR the tumor is larger than 2 but no larger than 5 centimeters and has not spread to the axillary lymph nodes.
Stage IIB	The tumor is larger than 2 but no larger than 5 centimeters and has spread to the axillary lymph nodes OR the tumor is larger than 5 centimeters but has not spread to the axillary lymph nodes.
Stage IIIA	No tumor is found in the breast. Cancer is found in axillary lymph nodes that are sticking together or to other structures, or cancer may be found in lymph nodes near the breastbone OR the tumor is any size. Cancer has spread to the axillary lymph nodes, which are sticking together or to other structures, or cancer may be found in lymph nodes near the breastbone.
Stage IIIB	The tumor may be any size and has spread to the chest wall and/or skin of the breast AND may have spread to axillary lymph nodes that are clumped together or sticking to other structures, or cancer may have spread to lymph nodes near the breastbone. Inflammatory breast cancer is considered at least stage IIIB.
Stage IIIC	There may either be no sign of cancer in the breast or a tumor may be any size and may have spread to the chest wall and/or the skin of the breast AND the cancer has spread to lymph nodes either above or below the collarbone AND the cancer may have spread to axillary lymph nodes or to lymph nodes near the breastbone.
Stage IV	The cancer has spread — or metastasized — to other parts