HER2+ Breast Cancer

Hello P4P Community!

It’s Whitney, here to tell you about HER2+ breast cancer. After recently finishing a project for my AP Biology class regarding this topic, I wanted to share my newly acquired knowledge.



HER2+ breast cancer is breast cancer that tests positive for human epidermal growth factor receptor 2 (HER2). This is a protein that promotes the growth of cancer cells. To provide some context, about 13% of women in the US will develop breast cancer, 20% of which will be HER2 positive.


The most common symptoms of HER2+ breast cancer are breast lumps, unusual breast swelling or tenderness, discomfort, thickening, or redness in a breast or nipple, unusual nipple discharge, or breast skin that appears irritated or dimpled.

Biological Explanation

Now, let's get into the biology of HER2! The HER2 gene creates HER2 proteins, which are hormone receptors. These receptors help control the growth and repair of breast cells. HER2 proteins also inhibit the mitochondrial pathway for apoptosis, which normally allows for the death of cancer cells. An over-expression of HER2 receptors leads to an overabundance of ligands carrying signals to reproduce breast cells, causing out of control cell reproduction.


Although HER2+ breast cancers are more aggressive than other types of breast cancer, treatments are very effective. Therefore, it has a relatively optimistic prognosis.

HER2+ breast cancer is commonly treated by surgery. Two examples of surgical procedures to treat breast cancer are a mastectomy, which is a complete removal of all breast tissue, and a lumpectomy, which is the removal of only a cancerous lump. Radiation is typically used prior to surgery in order to shrink tumors and widen margins for surgeons.

Arguably the most cutting-edge advancements in HER2+ breast cancer treatment lie within targeted therapies. For instance, Trastuzumab attaches itself directly to the HER2 protein in order to block cancer cells from receiving chemical signals that lead to growth. Pertuzumab is another drug that works similarly to Trastuzumab, but attaches to a different part of the HER2 protein. Often, Pertuzumab is used in combination with Trastuzumab, or with HER2+ breast cancer that cannot be removed by surgery. Finally, Lapatinib is a drug which blocks proteins that cause uncontrolled cell growth. This can delay the progression of metastatic breast cancer, even after it becomes resistant to Trastuzumab.


Finally, I want to share some intriguing research that I have recently begun working on with Dr. Joshua Drago, a medical oncologist at Memorial Sloan Kettering Cancer Center. Dr. Drago is conducting research on the effects of Antibody Drug Conjugates (ADC’s) on HER2+ breast cancer. In short, ADC’s are like little antibody missiles that detect certain antigens (you can think of antigens as identifying tags on cells) on HER2 proteins. ADC’s are very toxic but also very targeted, so they are able to kill cancerous cells while preserving healthy tissue. This allows doctors to spare patients from toxic treatments where the negatives outweigh the positives, hopefully improving patient outcomes.


I hope you enjoyed my shared information and I personally can’t wait to continue my research in this intriguing field.

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