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What You Need to Know about the Types of Breast Cancer

Understanding the different types of breast cancer can be confusing. Here are the most important things to know.

Awareness is the first step to taking control of your health and well-being. Each year, there are about 246,000 cases of breast cancer diagnosed in women. Familiarizing yourself with the different types of breast cancer can help you understand the importance of screening and being proactive regarding your breast health.

The Three Subtypes

If you’ve ever searched online for “breast cancer types,” you’ve probably come across more than a few confusing lists of medical jargon. The most basic way to understand breast cancer is to know the main subtypes that categorize all breast cancers.

“Breast cancers fall under three categories: hormone receptor-positive, driven by the hormones estrogen and progesterone; HER2-positive, driven by a protein called human epidermal growth factor receptor 2 (HER2); and triple-negative, cancer that doesn’t contain any of the three growth receptors—estrogen, progesterone or HER2,” says oncologist Dr. Casey Degen.

The most common type of breast cancer is hormone receptor-positive, making up about 60% of cases. HER2-positive and triple-negative each make up about 10% to 15% of breast cancer cases.

Breast cancer subtypes can be diagnosed by a pathologist who uses a microscope to look at a biopsy of the tumor with staining to see if it expresses the marker for hormone receptors, HER2 or none of the above.

Differences Among Subtypes

In general, these three types of breast cancers can all present in similar ways—from a small tumor that only shows on a mammogram to a very large, palpable tumor. “The biggest difference is that HER2-positive and triple-negative cancers tend to be more aggressive,” says Dr. Degen. “They can grow more rapidly than those driven by estrogen or progesterone alone.”

The other main difference between the types of breast cancer is in the way they’re treated. “It’s imperative for us to determine which subtype markers are present to come up with a treatment plan for each patient,” says Dr. Degen. For instance, if the cancer is hormone receptor-positive, hormone-blocking medication may be part of the treatment plan, but this same medication isn’t effective in treating HER2-positive or triple-negative breast cancer.

Outlook and Treatment Options

The outlook for breast cancer most often depends on the stage at which it’s diagnosed. “This is why regular screening is so important—finding cancer at an earlier stage means it’s easier to treat and it may even be curable,” says Dr. Degen. Breast cancer found in stages I through III is mainly treated through surgery, often accompanied by chemotherapy, radiation or other medications.

Metastatic breast cancer, considered stage IV, has spread to a distant location of the body, making it incurable but still treatable. “Generally we don’t recommend surgery for metastatic cancer, because the treatment needs to target the cancer in all areas of the body where it’s present,” says Dr. Degen. “Chemotherapy, immunotherapy or occasionally pills or injections are used in treating this type of cancer.”

Another factor that determines treatment options for breast cancer is the clinical presentation of the tumor. For instance, inflammatory breast cancer tends to affect the skin and lymphatic system instead of forming a mass in the breast—this means the cancer presents as red, inflamed and often thickened skin on the breast. “For inflammatory breast cancer, which is rare and often aggressive, we may recommend neoadjuvant chemotherapy,” says Dr. Degen. “This means we will use chemo to shrink and control the tumor before we use surgery to remove it.”

Risk Factors and Screening

The most common risk factors for breast cancer are older age and strong family history. “There are some types of breast cancer that are commonly associated with inherited syndromes,” says Dr. Degen. “People with the BRCA1 gene are often diagnosed with triple-negative breast cancer, while people with the BRCA2 gene often experience estrogen-positive breast cancer.”

All women should get yearly mammograms starting at age 40. Some may benefit from screening even earlier, especially if they have a strong family history, a previous pre-malignant breast lesion or a history of radiation to the chest area. If you have questions about your risk of breast cancer or how to get screened, talk to your primary care provider.

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