HER2 Classification for Breast Cancers
- HER2 "low" may become a new commonly classified subtype of breast cancer.
- HER2 "low" as a breast cancer type would include approximately 50% of all patients and opens the door for new treatments and research.
- Treatment for breast cancer depends on the stage and type; common breast cancer treatments include surgery, chemotherapy, and radiation.
This is exciting news for people diagnosed with breast cancer who may now have an even richer understanding of this disease as a result of new breakthroughs in medicine.
Read MoreOncLive reports how at a presentation during the 21st Annual International Breast Cancer Congress® West, Dr. Hamilton said that collaboration between pathologists and breast oncologists is a key piece regarding the classification of HER2 mutations in breast cancer.
Dr. Hamilton, who is the director of the Breast and Gynecologic Cancer Research Program at Sarah Cannon Research Institute in Nashville, Tennessee, tells OncLive, "What we traditionally classify as HER2-low is not HER2 0.”
Dr. Hamilton continues on to say that “improvements point toward the future of collaborative approaches of interpreting HER2 expression results.”
Understanding HER2 Breast Cancer
Traditionally, the presence of HER2 has been divided into two groups, either positive or negative, leaving about 50 percent of patients somewhere in the middle. These groupings are based upon the way the tumors appear under a microscope when graded by the pathologist or with additional testing a pathologist may perform.
Patients with HER2 positive tumors have tumors that show HER2 over-expression while patients with HER2 negative tumors show minimal or no expression.
Recently, however, researchers have looked to expand this definition further to include patients that have a minimal amount of HER2 expression but do not meet the classic definition for HER2-positive tumors. This group has been called HER2 "low" and is very important as it represents approximately 50 percent of all patients with breast cancer.
Treatment for HER2-Positive Breast Cancer
Treating Breast Cancer
For starters, let's take a look at what goes into the decision-making process for breast cancer treatments.
Related: What is Metastatic Breast Cancer?
Like most cancer patients, people with breast cancer are treated according to the stage of the tumor and factors specific to the tumor such as hormone receptors. Some of the most common factors in breast cancer that help physicians determine treatment include the presence or absence of the estrogen receptor, progesterone receptor and the presence of HER2 over-expression.
"These receptors, I like to imagine them like little hands on the outside of the cell, they can grab hold of what we call ligands, and these ligands are essentially the hormones that may be circulating in the bloodstream that can then be pulled into this cancer cell and used as a fertilizer, as growth support for the cells," Dr. Elizabeth Comen, a medical oncologist at Memorial Sloan Kettering Cancer Center, tells SurvivorNet.
"What we've learned is that some of these patients we thought were HER2 negative are actually HER2 low, which means that in this trial, they actually responded to targeted medications called T-DXd, or Enhertu, that targets the HER2 receptor, goes into the cancer cell, and kills it," Dr. Comen adds.
If you have or a loved one has been diagnosed with breast cancer, it's important to ask physicians about receptor status. All breast cancers should be routinely tested for these biomarkers as they are critical in helping the multidisciplinary team decide the best treatment for each patient.
For example, women with estrogen-receptor-positive breast cancers are typically treated with a combination of surgery, radiation therapy, hormonal therapy and sometimes chemotherapy.
In other women, with HER2-positive tumors, patients may also receive an additional drug called trastuzumab. Trastuzamab is a monoclonal antibody that specifically targets the HER2 receptor and typically is only given to patients with HER2 positive tumors.
Management of Metastatic Breast Cancer
Screening for Breast Cancer
The current guidelines from the American Cancer Society (ACS) say that women aged 45 to 54 with a regular risk of breast cancer should get mammograms annually.
For women with an elevated risk of breast cancer (who have a family history of the disease or carry the BRCA1 or BRCA2 gene mutation), you should begin screening before age 45. Speak with family members about your family cancer history it could save your life. Performing self-exams in the shower or at home is another good way to stay on top of breast cancer screenings; these should be done in addition to not in place of mammograms.
Related: Getting to Know Your Breasts with Self-Exams
Breast cancer is screened for via mammogram, which looks for lumps in the breast tissue and other signs of existing cancer, or cancer in its earliest stages. If a worrisome lump is detected, your radiologist or doctor will advise you on the next steps, which typically include a breast biopsy.
When Should I Get a Mammogram?
Contributing: James Taylor
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