Different types of breast cancer: Understanding your diagnosis
Most people know someone who has been diagnosed with breast cancer. Breast cancer is the second most common cancer in women in the United States (after skin cancer), affecting 1 in 8 women in their lifetimes.
Yet “breast cancer” isn’t one disease.
“People often expect breast cancer treatment to look a certain way, based on the experiences of friends or family members who have had the disease. But there are different types of breast cancer, and one person’s treatment plan can be completely different from someone else’s path,” says Andrea Merrill, M.D., a breast surgeon at Sentara Breast Surgery Specialists at Sentara Martha Jefferson Hospital.
If you or someone you know has been diagnosed with breast cancer, you may have a lot of questions. Here’s what to know about the different types of breast cancer.
Main subtypes of breast cancer
Cancer is defined by the place it starts. In the breast, it most often starts in one of two places:
- Lobular carcinomas start in glands called lobules, sac-like structures in the breast that produce milk.
- Ductal carcinomas start in the milk ducts inside the breast. The ducts are the tubes that carry milk from the lobules to the nipples.
Providers treat ductal and lobular carcinomas very similarly. However, lobular cancers have a different growth pattern that can be harder to detect on standard mammograms. As a result, they may be found at later stages and can be larger than they appear on a mammogram.
In situ vs. invasive breast cancer
When cancer is located only in ductal cells, it is described as cancer in situ (meaning “in the original place”—it hasn’t spread from its original location). Ductal carcinoma in situ (DCIS) is considered “stage 0” cancer, Dr. Merrill explains. “It’s kind of like a pre-cancer, but it will progress over time if it isn’t treated,” she adds.
Once cancer moves beyond the ducts into surrounding breast tissue, it’s known as invasive breast cancer. Most breast cancers—as many as 70-80 percent—are invasive ductal carcinomas.
While lobular carcinoma in situ (LCIS) sounds similar to DCIS, it is not considered a stage 0 cancer. Instead, it is considered a marker for higher future risk of breast cancer. Patients with LCIS typically do not need surgery, but they should be followed in high-risk breast clinics, Dr. Merrill explains. “These patients should consider MRI breast screening to look for signs of cancer. And some patients with LCIS may benefit from medications that reduce their risk,” she adds.
Breast cancer tests and types
If you have suspicious mammogram results, the next step is usually a needle biopsy to sample tissue from the area. By examining that tissue, doctors can identify whether cancer is present, what type it is and how likely it is to spread.
Ductal and lobular carcinomas have different subtypes based on certain characteristics of the cancer cells. Tests can reveal information about the proteins and even the genes present on the cancer cells. “By learning about the unique characteristics of each individual breast cancer, we can choose the treatment path that’s most likely to be effective,” Dr. Merrill says.
She explains some of the common cancer types.
Hormone-positive and hormone-negative breast cancers
Some breast cancers contain proteins, called receptors, that make them sensitive to the hormones estrogen or progesterone:
• Estrogen receptor (ER)-positive tumors: The presence of estrogen makes them grow.
• Progesterone receptor (PR)-positive tumors: The hormone progesterone stimulates cancer growth in these tumors.
A breast tumor could be sensitive to one hormone, both or neither. Cancers that aren’t sensitive to estrogen or progesterone are called hormone-negative or HR-. Those that are sensitive to one or both are classified as hormone-positive or HR+.
HR+ cancers are the most common type. For those cancers, treatments that block the effects of the hormones can slow or stop the cancer from growing and reduce the risk of the cancer coming back after surgery.
HER2 breast cancer
Doctors also test tumor cells for the presence of HER2, a protein that helps cancers grow. Cancers that have higher-than-usual levels of the protein are called HER2-positive.
HER2-positive cancers are more likely to grow and spread quickly. “But the good news is that we now have treatments that directly target the HER2 receptor, and HER2-positive cancers tend to respond really well to those treatments,” Dr. Merrill says.
Triple-negative breast cancer
Some cancers are negative for estrogen receptors, progesterone receptors and HER2 receptors. These are known as triple-negative cancers. “These cancers are more aggressive than other types and often require more aggressive treatment,” Dr. Merrill says. “But new treatments for triple-negative breast cancer have significantly improved outcomes and survival rates in the last few years.”
Inflammatory breast cancer
Inflammatory breast cancer is a rare type of invasive carcinoma. It’s more likely to be ductal in origin, though it can also come from the lobules. It can also follow any profile for hormone receptors.
Unlike other types, inflammatory breast cancer may not cause a lump. It often shows up as swelling and redness on the skin of the breast, Dr. Merrill explains. The skin might be firm or dimpled like an orange peel over a large portion of the breast. It typically isn’t painful and can sometimes be mistaken for an infection called mastitis.
“Inflammatory breast cancer is rare but aggressive,” Dr. Merrill says. “If you notice significant changes to the skin of your breast, including symptoms that resemble an infection, get it checked out right away.”
Targeted breast cancer treatment
Making sense of a new breast cancer diagnosis can feel overwhelming. “I often tell my patients that the pathology report is written in English—but not really,” Dr. Merrill says.
Breast cancer specialists are experts in understanding the fine print. “I walk my patients through each section of the lab report, so they understand the details and how that information helps us decide about the next steps,” she says.
Treatment can vary depending on the breast cancer type. Some patients have surgery first, then follow up with treatments like chemotherapy or radiation therapy. Others have chemotherapy or targeted drug treatment first to shrink the tumor before having surgery. Some cancers respond to immunotherapy treatments, which help the body’s immune system find and fight cancer cells.
“It’s a promising time for breast cancer treatment. There are important findings and therapies coming out all the time that are improving how we treat breast cancer,” Dr. Merrill says. “Understanding all of the unique features of the cancer helps inform our discussions as we come up with a treatment plan.”
Compassionate care at Sentara Breast Surgery Specialists
A breast cancer diagnosis is never easy. But arming yourself with information increases the chances of successful treatment.
“Don’t put off getting your mammogram, and don’t be afraid to share your wishes and concerns with your treatment team,” Dr. Merrill says. “I talk with each patient about their unique beliefs and treatment goals. That, combined with the latest science, will point us in the right direction as we discuss the best path forward.”
Andrea Merrill, M.D., is a breast surgeon with Sentara Breast Surgery Specialists at Sentara Martha Jefferson Hospital. Call 434-654-8715 to schedule an appointment.