The Most Common Types of Breast Cancer: Invasive vs. Non-invasive

Invasive Ductal Carcinoma is the most common type (80%) followed by Invasive Lobular Carcinoma. DCIS: the cancer cells are still inside the malls of the ducts

Others: Lobular Carcinoma in Situ, Inflammatory Breast Cancer (looks like an infection), Paget’s Disease (involves the nipple/areola), Malignant Phyllodes Tumors (from the connective tissue of the breast)

Pathology Reports

Invasive vs. Non-invasive
Ductal vs. Lobular
Grade: how abnormal are the cells; 1-3. 1 means the cancer cells look the most similar to normal breast cells. 1 is the best, 3 is the worst.
Hormone Receptor Status: ER/PR +/-. Do the cancer cells respond to estrogen or progesterone as growth signals. We want the cancer to be receptor positive so we can use hormone therapy to treat and prevent the cancer.
HER2 Status: The HER2 gene makes HER2 proteins or HER2/neu proteins. These are receptors on breast cells that normally help control how a healthy breast cell grows, divides, and repairs itself. If the HER2 gene doesn’t work correctly and makes too many copies of itself and too many HER2 proteins we call this HER2 protein overexpression. This makes breast cells grow and divide in an uncontrolled way. The Immunohistochemistry (IHC) test gives a score of 0 to 3+. 0 or 1+ is considered negative, 2+ is considered borderline, and 3+ is considered positive. The Fluorescence In Situ Hybridization (FISH) test is more accurate but takes longer and is more expensive. With the FISH test the result is either positive or negative. We want it to be negative.
Ki-67 %: This measures a protein only produced in cells when they are actively dividing. Anywhere from 0 - 100% of cancer cells can be dividing at any time. The higher the percentage, the faster the cancer growth. <10% is considered low, 10 - 20% is considered intermediate, and >20% is considered high. We want it to be <20%.
Staging: Clinical (before surgery) versus Pathologic (based on tissue from surgery). 0 to 4. Stage 0 is non-invasive cancer, and stage IV is metastatic cancer that has spread elsewhere in the body.
TNM staging: T for tumor size and invasion, N for if the cancer cells are in the lymph nodes, M for if the cancer has spread to different organs
Lymph Node Status: lymphatic fluid travels through the body helping to get rid of waste or unwanted materials and cancer cells can use that system to spread. Lymph nodes are the filters along that system to trap bacteria, viruses, cancer cells, and other unwanted substances.
Margins: During surgery we want to remove the cancer plus a rim of healthy tissue all around it. This gives us “clear margins” when the pathologist looks at the area under the microscope.

Genetic Testing

Everyone inherits copies of genetic material (genes) from each of their parents. Some changes or mutations in the genes can tell cells to make or not make proteins that affect how the cell grows and divides. Certain mutations can cause cells to grow out of control, which leads to cancer.

Three of the most well-known genetic mutations that predispose to increased risk of breast and ovarian cancer are BRCA1, BRCA2, and PALB2

Surgery: Breast Conserving Surgery or Mastectomy

A mastectomy will remove about 95% of the breast. Breast conserving surgery (lumpectomy) involves only removing the tumor from the breast. You will require post-operative radiation if you undergo breast conserving surgery.
A lymph node evaluation is often accomplished at the time of surgery as well to check for cancer cells in the lymph nodes. This often a less invasive procedure called a sentinel lymph node biopsy where just a few nodes are removed.