Understanding staging and types of breast cancer
From HER2 to hormone receptors, LCRP Medical Director Dr. Howard A. Zaren breaks down breast cancer types and subtypes
Invasive versus non-invasive. HER2 positive. HER2 negative. Hormone positive or negative. What does it all mean when it comes to understanding your and someone you love’s breast cancer?
Breast cancer is the most commonly diagnosed cancer in women, occurring in one out of eight females. In 2017, more than 250,000 new cases of invasive breast cancer were diagnosed in women, according to the American Cancer Society. Additionally, more than 60,000 non-invasive breast cancers were diagnosed and a total of nearly 40,000 deaths occurred because of the disease.
The good news is that the death rate is going down about 1.9 percent a year, says Dr. Howard A. Zaren, MD, FACS, Nancy N. and J.C. Lewis Cancer & Research Pavilion Medical Director.
“It’s due to better treatment, better screening and modification of lifestyle, such as discontinued use of postmenopausal hormones, stopping smoking, diet and exercise and limiting alcohol use,” Dr. Zaren says. “Women should know that it’s not the end of life with a breast cancer diagnosis.”
The stage, type of cancer and molecular subtype can help determine the best course of treatment for each individual breast cancer patient and improve survival.
How is breast cancer staged?
Staging of cancers describes how much cancer is in the body; basically, if it has spread and how far. Breast cancers are staged 0 through IV. Stages change all the time, Dr. Zaren says, as your cancer team learns more about your cancer and treats it.
Sixty percent of all breast cancers are localized to the breast, which has a five-year survival rate of 98 percent, Dr. Zaren says. Another 30 percent are localized to the breast and lymph nodes.
“The best situation with the best survival is breast cancer that involves just the breast, below five centimeters in size,” Dr. Zaren says. “The next is breast cancer that involves not only the breast but has metastasized to the lymph nodes. Still, that has a good survival rate of about 85 percent.”
Even the most advanced stage breast cancers (often referred to as metastatic breast cancer, which spreads outside the breast and lymph nodes to other organs) are seeing an improved survival rate thanks to new treatment.
What are the types of breast cancer?
There are many different types and subtypes of breast cancer. It starts with the pathology terms of either non-invasive or invasive, or infiltrating. Non-invasive cancers stay within the milk ducts or glands in the breast. Invasive cancers break through the walls of the glands or ducts and invade surrounding breast tissue, Dr. Zaren explains.
In situ breast cancer is non-invasive breast cancer and occurs in about 20 percent of all breast cancers. Ductal carcinoma in situ (DCIS) accounts for 83 percent of non-invasive cases. DCIS refers to a condition in which abnormal cells replace the normal epithelial cells that line the breast ducts. DCIS may or may not progress to invasive cancer.
Lobular carcinoma in situ (LCIS) accounts for 13 to 15 percent of the non-invasive breast cancers. LCIS refers to abnormal cells growing within and expanding some of the lobules of the breast. LCIS is more of a risk factor for developing invasive cancer as opposed to an actual cancer, Dr. Zaren says.
The most common type of breast cancer is invasive ductal carcinoma (IDC), accounting for about 80 percent of all breast cancers. IDC begins in the milk duct and grows into the surrounding normal tissue inside the breast.
To better plan treatment, invasive breast cancer can be broken down into molecular subtypes. These subtypes are determined by cancer cells’ hormone receptor status (estrogen and progesterone positive or negative) and their HER2 status.
When the hormones estrogen and progesterone attach to protein in cancer cells it fuels cancer growth. Cancers are called hormone receptor-positive or hormone receptor-negative based on whether or not they have these receptors.
HER2/neu, typically referred to as HER2, is a growth-promoting protein on the outside of all breast cells. Breast cancers with higher levels of HER2 are called HER2 positive.
Luminal A: The most common molecular subtype is luminal A, presenting in about 70 percent of patients. Luminal A is estrogen positive, progesterone positive and HER2-negative. Luminal A is the best cancer to have, Dr. Zaren says, because of its favorable prognosis in part because it’s more responsive to anti-hormone therapy.
Luminal B: Luminal B breast cancer is also hormone-receptor positive but also HER2-positive. This accounts for about 15 percent of all breast cancers. Luminal B cancers are more aggressive than luminal A, but survival is still good, Dr. Zaren says.
Triple negative breast cancer: Accounting for about 12 percent of breast cancers, triple negative is both hormone-receptor and HER2 negative. This type of breast cancer disproportionately affects African-American women and premenopausal women. There’s also a significant portion of women with triple negative breast cancer that are positive for the BRCA gene, a well-known gene that if altered increases your risk for breast and ovarian cancers.
HER2-enriched: The least likely molecular subtype of breast cancer, but also the most aggressive, is estrogen and progesterone negative but HER2 positive. This accounts for about five percent of breast cancers. The cancer spreads more aggressively than other subtypes and has a poorer short-term prognosis. However, new targeted therapies are improving outcomes for these patients.
How does staging and type determine your treatment plan?
At the Lewis Cancer & Research Pavilion, a multi-disciplinary team of oncologist, surgeons, radiation oncologists, nurse navigators and others review each individual patient case to help determine the best course of treatment. Often times, the stage and characteristics of the cancer help guide this decision.
While each case is individualized, there are several options to treat breast cancer including surgery, chemotherapy, radiation therapy and hormone therapy.
When is the last time you’ve had a mammogram?
It would be careless to talk about breast cancer without referencing screening. More than 60 percent of breast cancers are diagnosed through mammography. The other 40 percent are found by self-examination or physician examination.
Dr. Zaren recommends a mammogram every one to two years for women after the age of 40, and sooner if there’s a family history. He also recommends monthly, or at least quarterly, self breast exams. If you have a strong family history, especially a first-degree relative who had cancer at a young age, you also may want to be tested for the BRCA gene, Dr. Zaren encourages.
If it’s time for your yearly mammogram, St. Joseph’s/Candler has five area locations that offer 2D and 3D mammography. Learn more here.