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Why So Many Types of Breast Cancer Treatment?


Successfully treating breast cancer means getting rid of the cancer or getting it under control for an extended period of time. But because a breast cancer is made up of many different kinds of cancer cells, getting rid of all those cells can require different types of treatments.

Your treatment plan may include a combination of the following treatments:

Designing your personal treatment strategy to treat breast cancer requires a lot of careful thought. The ideal treatment plan works against all the things inside the cells that caused the cancer to develop, are making it grow, and may make it spread to other parts of the body.


Every Cancer Is Different

Cells are the building blocks of every living thing — from tomatoes to ladybugs to salmon to people. The instructions that tell a cell what to do are in genes within the center of the cell. Those genes are made of DNA (deoxyribonucleic acid). DNA can change or be damaged over time. Some DNA changes are harmless, but others can cause disease. Cancer cells are “born” when abnormal changes in DNA tell cells to grow faster and behave differently than they should. As these cancer cells multiply to form a tumor, they continue to change — becoming more and more different from each other.

As a cancer grows, new and different types of breast cancer cells are created within that same cancer. The mixture of cells that builds up over time becomes more and more complex. So even though every cell of a cancer is related to the same original "parent" cell, all the cells that make up a cancer are not the same. The idea that different kinds of cells make up one cancer is called "tumor heterogeneity."

By the time a breast cancer tumor is one centimeter (less than half an inch), the millions of cells that make up the lump are very different from each other. And each cancer has its own genetic identity, or fingerprint, created by the DNA in its cells. So two people with breast cancer who are the same age, height, weight, and ethnicity, and who have similar medical histories, almost surely have two very different cancers. The only thing the cancers have in common is that they started from a breast tissue cell.


Different Cancer Cells Need Different Treatments

The differences among cancer cells (tumor heterogeneity) is why your pathology report, blood tests, and other tests can be so complicated and why there are so many different treatments for breast cancer. Because the cancer cells can be so different, what kills one type of cell might not do anything to another.

The best overall treatment involves getting the best out of each specialty. Surgery, radiation, chemotherapy, hormonal therapy, and targeted therapies all work in different ways on their own — plus they can be extra effective when given together.

More than one hundred medications have been approved to treat cancer, and many more are being developed. Some treatments are very specialized, designed to target only a particular gene or protein in the cancer cells. This targeted therapy might do its job well, but that's only one part of the overall fight against the cancer. Other treatments are needed to fight other targets in the cancer cells. Each treatment does its part to get rid of the whole cancer. This is why some treatments work best in combination with other treatments or before or after other therapies.

The differences in cancer cells are why two people with breast cancer may have completely different treatment plans. You may meet other people in the waiting room before your exams or therapies. It's quite common to share stories about diagnosis and treatment. Remember, though, that each cancer has a different personality and will have a different treatment plan. When you're talking to someone else, it's hard to know if her situation is similar to or different from yours. So you won't want to make decisions about your own treatment based on what someone else is doing. What's working for her may be different than what's working for you.

A more complete picture

Targeting specific characteristics of cancer cells, such as a protein that allows the cancer cells to grow in a rapid or abnormal way, has led to the development of a number of new treatments. For example:

  • Hormonal therapy medicines target hormone receptors that cause cancer cell growth.

  • HER2 inhibitors work against HER2-positive cancers by blocking the cancer cells’ ability to receive growth signals.

  • CDK4/6 inhibitors work against metastatic breast cancers that are hormone-receptor-positive and HER2-negative by stopping the cancer cells from dividing and growing.

  • PARP inhibitors work against metastatic HER2-negative breast cancer with a BRCA1 or BRCA2 mutation by making it difficult for cancer cells to fix DNA damage.

  • PI3K inhibitors work against HER2-negative breast cancers with a PIK3CA mutation.

Researchers suspect that other specific genes in individual breast cancers can be identified. Once discovered, it’s possible that treatments can be developed to target those specific genes.

Genomic tests analyze certain genes in breast cancer cells. By measuring the activity levels of specific genes, these tests calculate a recurrence score. The higher the recurrence score, the more likely the cancer is to come back. Looking at the cancer's other characteristics AND genomic test results can help predict the risk of cancer coming back. This information can help women and their doctors decide other treatments after surgery would be beneficial.

Researchers hope to develop tests that can give us a fuller, more complete picture of a cancer tumor's genetic makeup. Then treatments can be prescribed that are personalized for each cancer.


Tumor Resistance

Over time, it's possible for a tumor to develop resistance to treatment. This is when cancer cells figure out how to survive against treatments. This might happen when various treatments kill the cells they know how to kill but don't work against every last cancer cell. The cells that escaped the killing-effects of earlier treatment are called resistant cells. They survive the prior treatment attack and eventually grow. This is how recurrence can happen.

To get rid of these resistant cancer cells, you need new forms of treatment that work differently from treatments you had before. Sometimes a second round of treatments might be able to get rid of all the leftover cancer cells. But in other situations, additional rounds are needed.

— Last updated on January 21, 2022, 5:27 PM

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