Breast Cancer

What is Breast Cancer

Breast cancer is the most common cancer diagnosed in women. Breast cancer are cells that are formed in the breast and grow out of control. The kind of breast cancer is determined by the cells in the breast that turned into cancer. Breast cancer is not localized, therefore, can begin in any parts of the breast. Breast cancer though majority common in women can also occur in men as well.

Breast Cancer discovery

Breast cancer is often discovered on a mammogram. If there appears to be a suspicious area on the breast; then, a biopsy will take place. After it has been confirmed that it is cancer, your doctor will start the staging process. This process is to determine if the cancer has spread and how to treat it. Your doctor will provide you with a clinical stage before surgery by using the sample from the biopsy to determine the diagnoses, stage, and treatment plan for your breast cancer. Diagnostic testing, such as a biopsy, CT scan, PET scan, and MRI provides additional information about your tumor. Medical providers group the tumor by a system known as


  • Tumor (T): Tumor (T): T1, T2, T3, and T4 are primarily used to explain the extent of the original tumor. For instance, the size and location of the tumor will be taken into consideration.
  • Node (N): N1 is used to show that cancer cells are present in the lymph nodes. This group will indicate if the tumor has spread to the lymph nodes and how many lymph nodes are involved.
  • Metastasis (M): is usually used to show that cancer cells have/ have not spread to other parts of the body. This group will indicate where the cancer has spread to and how much of the body/organ is impacted.

Types of Breast Cancer

Determining where the breast cancer started and has spread to, will determine the classification of the cancer and the treatment plan. Invasive (or infiltrating) carcinoma begins in the lobule of the cells lining a duct

Invasive Lobular Carcinoma
Breast cancer that starts in the lobules is called Invasive Lobular Carcinoma (ILC). It is also referred to as infiltrating lobular carcinoma and is the second most common form of breast cancer. This type of breast cancer starts in the lobules, the cells lining a duct (milk passage) of the breast and can potentially spread to other parts of the body. ILC is more likely to appear in both breasts. ILC accounts for a smaller percentage of breast cancer.

Invasive Ductal Carcinoma
Meanwhile, breast cancer that starts in the ducts and grows through into surrounding tissue is called Invasive Ductal Carcinoma. IDC is the most common form of invasive breast cancer. The cancer can potentially spread to other parts of the body, referred to as metastasis.

Ductal Carcinoma in Situ

Cancer that starts in the ducts, which is the most common form of non-invasive breast cancer, is called Ductal Carcinoma in Situ (DCIS). DCIS can also be referred to as intraductal carcinoma and/or Stage 0 breast cancer. DCIS is an indication that the cells lining the duct have become cancerous. This form of cancer is noninvasive or pre-invasive breast cancer.

Breast Cancer Stages

Note: Early-stage breast cancer is stage 0, I, and II

Stage 0
This stage of breast cancer is noninvasive, started in the milk duct and has not spread anywhere else in the body. The term “in situ”, meaning the cancer has remained in its original place.

Stage I (characterized into two groups, IA and IB)
During Stage IA, breast cancer has spread into fatty breast tissue The tumor appears to be smaller than a shelled peanut. On the other hand, Stage IB is a detection of tiny cancer cells and may present in some lymph nodes.

Stage II (characterized into two groups, IIA and IIB)

Stage II indicates that breast cancer is progressively growing. The two stages are distinguished by the size of the tumor and/or whether the breast cancer has advanced to the lymph nodes. Breast cancer may only be in the breast and/or has spread to nearby lymph nodes. Stage IIA Breast Cancer is identified by the following characteristics: the tumor is still small, or a tumor may not be present. Cancer may not exist in lymph nodes or has spread to no more than three lymph nodes. Yet, Stage IIB the cancer appears bigger in size (compared to a lime). The lymph node may or may not be involved. 

Stage III(characterized into two groups, IIA, IIB, and IIC)
This stage is identified as being a locally advanced form of the disease. The tumor is larger and is about 2 inches in diameter. Stage IIIA describes the tumor as ranging from 2-5 cm with the involvement of further lymph nodes of the axilla and the breastbone. The breastbone lymph nodes are affected with or without the presence of a tumor. This is also attached to the lymph nodes under the arm. In the same token, Stage IIIB indicates that several lymph nodes under the arm and near the breastbone are affected; this is with any size of the tumor. Additionally, inflammatory breast cancer has reached the skin of the breast and the chest wall. Stage IIIC diagnosis implies there is skin and chest wall involvement with no obvious sign of cancer. The lymph nodes around the breastbone and the collarbone are affected together with axillary lymph nodes.

Stage IV
Apart from the other stages of breast cancer, Stage IV is more aggressive. Taking that into account, the cancer has spread beyond the breast and lymph nodes. Often, the cancer will spread to the bones, brain, liver, or lungs. Stage IV is more aggressive, which means treatment must be aggrieved. Depending on where the cancer has spread, treatment plans will vary.

Receptor Status

Estrogen (ER+) and Progestin (PR+)
Breast cancer is not a single disease. The disease is broken down in different subtypes, such as the receptor status of the tumor. Roughly 70% of breast cancer are hormone receptor- positive and will appear on the pathology report. The pathology report, obtained by one’s biopsy and/or surgery, will indicate the hormone receptor status. Medical providers tend to focus on the estrogen and progestin status. Estrogen and progestin receptors impact the growth of the cancer cells. Cancerous breast cells, such as ER+ and PR+ will attach to receptors and fuels the cell growth and division. To illustrate, hormone receptors are much like proteins on the surface of breast cells. When the hormone receptors bind (fasten onto) to the cancer cells, the cells start to grow and divide. Equally important, knowing one’s menopause status is important. Pre-menopause stage suggests that the ovaries are producing the greatest amount of estrogen. Meanwhile, post-menopause indicates that less estrogen is being produced. However, the body continues to produce androgens (male type of hormone), which is converted into estrogen.

Human Epidermal Growth Factor Receptor Proteins (HER2)
HER2 promotes the growth of cancerous cells in the body and tends to be more aggressive. If one is diagnosed with invasive breast cancer, the presence of HER2 is often tested. HER2 receptors are involved in normal cell growth and are located on the breast cells. When abnormally high levels of HER2 receptors are produced, this can cause some types of breast cancer to spread and grow. HER2 positive breast cancer cells contain 40-100 more receptors than HER2 negative. By knowing the protein and/or hormonal levels, medical providers can address and stop the spread of the breast cancer.

Triple Negative and other Factors
Some breast cancer can have different receptors. For instance, ER+, PR-, and HER2+ can exist. In cases where ER-, PR-, and HER2- (referred to as Triple Negative) indicates the growth of the cancer cells are not fueled by excessive HER2 proteins and the hormones estrogen and progesterone.

Understanding Your Pathology Report

Discovering a lump or spot on the breast does not always indicate cancer is present. In order to distinguish normal cells from cancer cells (atypical cells), a biopsy will be completed. When a tissue is taken from the body to check for cancerous, a pathology report is completed. The results of the removed tissue will be noted on the pathology report. Pathology reports help medical providers understand the cancer and the form of needed treatment. Specimens for breast cancer are either taken from the breast, lymph nodes, or both areas. If the cancer has spread to other areas of the body, such as the liver, tissue samples from that area may also be taken. The pathology report will identify the characteristics and type of breast cancer.

(Note: different labs may use different languages to describe the specimen).

To begin with, the type of cancer, such as DCIS or IDC) will be noted in the pathology report. Next the Grade will be provided, which is different from the stages of breast cancer. The grade helps to differentiate normal cells from cancer cells.

There are three grades provided:

Grade 1

Grade 2

Grade 3

Low grade

intermediate, and
differentiated from
normal cells

High grade, poorly
differentiated, and
looks quite different
from normal cells.

Appears a little
different from normal

Cancer cells are
slowly growing

Cancer cells are
growing a little faster
than normal cells

Cancer cells are
growing faster.

The pathology report may also show the Ki-67, which describes the rate of the cancer cell’s growth. Much like ER+ and PR+, Ki-76 is considered a cancer’s protein. The protein is found in dividing and growing cells. Tumor cells are measured by the percentage of Ki-67 that test positive. Ki-67 positive indicates the cancer cells are quickly growing and forming new cells.


10% considered low

10%-20% considered intermediate/borderline

20% considered high