Understanding What Chemorefractory Means

Most people have heard of the terms, "cancer" and "chemotherapy." But besides the fact that chemotherapy is used to treat cancer, most people are unfamiliar with the nuances associated with chemotherapy, like what the specific term "chemorefractory" means.

In short, "chemorefractory" has to do with the response to chemotherapy drugs. To best understand "chemorefractory," let's begin with the basics on chemotherapy.

Chemotherapy Basics

There are over one hundred different types of chemotherapies used by cancer doctors (called oncologists). Depending on a person's specific type of cancer and the stage of the cancer, an oncologist will choose one or a combination of chemotherapy drugs.

Administration

Chemotherapy can be given in many different ways. Some drugs can be taken by mouth (for example, as a tablet or in liquid form) whereas others are administered as an injection, either into the muscle or fatty tissue.

Other chemotherapies are administered into the cerebrospinal fluid through a spinal tap (called intrathecal chemotherapy), into the abdomen through a catheter, into the chest through a chest tube, or even topically (on top of the skin).

Overall, though, the vast majority of chemotherapies are given through a person's vein, and this is called an intravenous infusion.

Mechanism

Chemotherapy works by killing cells that grow rapidly, like cancer cells.

Some normal, healthy cells, though, also grow rapidly, like cells in the mouth and stomach, blood-forming cells, and cells that make hair. This is why some people lose their hair when taking certain types of chemotherapy, develop nausea and mouth sores, become anemic, and/or develop a low number of infection-fighting cells (called white blood cells).

While chemo works by killing cancer cells, it's purpose may vary. In other words, the goal or expected outcome of undergoing chemo is not the same for every person.

For instance, while chemotherapy is traditionally given to cure cancer, it may be used instead to shrink a tumor enough to ease pain related to the cancer (called palliative chemotherapy) or shrink a tumor prior to surgery (called conversion chemotherapy).

Response

Response, which is measured at specific periods of time (usually after two to three cycles of chemotherapy), refers to how effective the chemo drugs are at killing the cancer cells.

Doctors measure response in different ways based on the specific type of cancer. For instance, a doctor may order interval CT scans and/or blood tests to measure a tumor marker. These tests are repeated at regular periods of time, so they can be compared.

Response and Its Connection to "Chemorefractory"

The terms "chemorefractory" or "chemosensitive" cancer describe the responsiveness of a cancer to the drugs combating it.

If a cancer responds to the chemotherapy, meaning it shrinks or vanishes after a person receives the chemo drugs, the cancer is described as "chemosensitive."

On the flip side, if a cancer is "chemorefractory," it does not shrink or vanish in response to the administered chemo drugs.

Sometimes a cancer that is chemorefractory may be described as a "failure of cancer chemotherapy," or a "resistance to chemotherapy."

It's important to note that a cancer can be refractory to chemotherapy right away (like at the beginning of treatment) or it may become refractory during treatment.

In other words, a tumor may initially respond to chemotherapy and get smaller, only to stop responding and not change size, or even get bigger.

More specifically, when describing the response (or lack of response) to chemotherapy, oncologists use these terms:

• A complete response has been said to occur when all of the cancer vanishes.

• A partial response means that the cancer has shrunk but is not completely gone.
• A stable response means that the cancer has not shrunk, but it also has not grown.
• If a cancer progresses, it has grown, meaning there is more cancer present than before chemotherapy was given. In this case, a doctor may stop chemotherapy and/or change to a different chemotherapy.

Why Your Cancer May Be Chemorefractory

There are many reasons why a cancer may be chemorefractory and understanding these reasons is key to improving treatment results. One reason is that the cancer cells may undergo a change in their genetic makeup, which makes them resistant to the chemotherapy. Another devious way that cancer cells  become chemorefractory is by sneakily pumping the chemo drug out as soon as it enters their membrane.

Other ways include:

• Cancer cells may learn how to repair their own DNA breaks caused by certain chemo drugs.
• Cancer cells may develop a "thick skin" so to speak, making their membranes less permeable, so the chemo cannot enter.
• Cancer cells may even devise a way to inactivate the drug, rendering it ineffective.

This all said, it's important to note that if your cancer is chemorefractory, it's not your fault—there is nothing you did or didn't do that caused the cancer to not respond.

Minimizing Your Chances of Your Cancer Being Chemorefractory

To reduce the likelihood of a chemorefractory cancer, oncologists are precise in giving patients the best chemotherapy regimen first. This is because once a cancer becomes chemorefractory to one chemo drug or group of chemo drugs, the likelihood of it being resistant to other chemo drugs is high.

Furthermore, oncologists usually give a combination of chemo drugs to overwhelm the cancer before it can become resistant—in other words, using their strongest weapons first.

In addition to choosing the chemo drugs that show the best response rate based on research, your oncologist will also take into account other factors when choosing your chemo drugs, like your physical health outside of your cancer, as well as the toxicity profile (the side effects) of the chemotherapy.

A Word From Verywell

While being told you have a chemorefractory cancer is anxiety-ridden and distressing, it does not mean there are no options left for your cancer care. Sometimes, it means switching to a different chemotherapy regimen or a new type of treatment altogether.

Be reassured that researchers are working tirelessly to find ways to optimize cancer response rates and minimize chemotherapy resistance. Even more, the treatment of cancer is heading in new directions, as evidenced by the emergence of immunotherapies.

Sources:

American Cancer Society. (2017). Chemotherapy.

Cleveland Clinic Chemocare. (2017). What is Chemotherapy?

Krol M, Pawlowski KM, Majchrzak K, Szyszko K, Motyl T. Why chemotherapy can fail? Pol J Vet Sci. 2010;13(2):399-406.

National Cancer Institute. Definition of refractory cancer.

Sforza V. Clinical outcome of patients with chemorefractory metastatic colorectal cancer treated with trifluridine/tipiracil (TAS-102): a single Italian institution compassionate use programme. ESMO Open. 2017;2(4):e000229.