Understanding What Chemorefractory Means

When Chemotherapy Fails

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Chemorefractory is a term that is used to describe a cancer that does not respond to chemotherapy (chemo) medications.

Cancer can be refractory to chemotherapy right away or it may become refractory during treatment. In other words, a tumor may respond to chemotherapy at the beginning and get smaller, only to stop responding and not change size—or even get bigger—later on.

This article goes over the basics of chemotherapy and why cancer can be chemorefractory. It also discusses steps healthcare providers take in an effort to prevent cancer from being unresponsive to this treatment.

What Is Chemotherapy?

There are hundreds of different types of chemotherapy. Your cancer care provider (oncologist) will choose chemo drugs based on the type of cancer you have.

For some cancers, you might only need one chemo drug. Other cancers need to be treated with a combination of chemo drugs.

How Chemo Is Given

Chemotherapy can be given in several ways. The way that is best for you will depend on the type of cancer you have and other factors about your health.

Some of the most common ways to get chemo are:

  • Through a vein (intravenous infusion)
  • A shot (injection) in a muscle or fatty tissue
  • In your cerebrospinal fluid during a procedure called a spinal tap (intrathecal chemotherapy)
  • In your abdomen through a catheter or into your chest through a chest tube

You can also get chemo in ways that don't involve a needle, including:

  • As a tablet or liquid that is taken by mouth (oral)
  • On your skin (topical) as a cream or lotion
chemotherapy infusion
 Verywell / JR Bee

How Chemo Works

Chemotherapy works by killing cells that grow very fast. This includes cancer cells.

However, there are some normal, healthy cells—like those in your mouth and stomach, blood-forming cells, and cells that make hair—that also grow fast. Unfortunately, chemo doesn't discriminate between the two.

When these healthy cells are also affected by the medication, it can cause some of the common side effects of chemo.

For example, some people lose their hair, have nausea, get mouth sores, have low numbers of red blood cell counts (anemia), or have low numbers of infection-fighting cells (white blood cells) while they are getting treatment.

While chemo's job is to kill cancer cells, the goal of having the treatment is not the same for every patient.

For example, chemotherapy can also be used to:

Response to Chemo

Response to treatment describes how effective the chemo drugs are at killing cancer cells. Your response to treatment will be measured at different times—usually, after you've had two to three cycles of chemo.

Your providers can check your response to the treatment in different ways, depending on the type of cancer you have.

For example, your provider may want you to have imaging scans to look at the tumor and your organs. You might also need to have blood tests to measure substances called tumor markers.

The tests are repeated and your provider will compare the results to get a sense of how well the treatment is—or isn't—working.

What the Terms Mean

Cancer doctors use several terms to talk about how cancer is responding to treatment:

  • Complete response: All cancer goes away
  • Partial response: Cancer has shrunk but is not completely gone
  • Stable response: Cancer has not shrunk, but it also has not gotten bigger
  • Cancer has progressed: Cancer has grown and there is more cancer now than before treatment started (in this case, chemo might be stopped and/or changed to a different type)

The terms "chemorefractory" or "chemosensitive" describe how the body is responding to cancer treatments.

  • Chemosensitive: This means cancer responds to the medications, and it shrinks or goes away after a person receives chemo.
  • Chemorefractory: This means cancer does not shrink or go away when the chemo drugs are given. Sometimes, cancer that is chemorefractory is called a "failure of cancer chemotherapy," or a "resistance to chemotherapy."

Why Cancer Is Chemorefractory

There are many reasons why your cancer could be chemorefractory.

  • Cancer cells change their genetic makeup and become resistant to chemotherapy.
  • Cancer cells pump the chemo drug out as soon as it gets inside them.
  • Cancer cells learn how to repair their own DNA breaks that were caused by chemo drugs.
  • Cancer cells may make their membranes thicker so the drugs can't get inside them.
  • Cancer cells may inactivate the chemo drug so it doesn't work anymore.

If your cancer is chemorefractory, know this: There is nothing you did or didn't do that caused your cancer to not respond to treatment.


To reduce the chances of chemorefractory cancer, oncologists take their time to make sure they are giving patients the best chemotherapy regimen first.

Once cancer becomes chemorefractory to one chemo drug or group of chemo drugs, the chances that it will be resistant to other chemo drugs is high.

Oncologists usually give a combination of chemo drugs to overwhelm cancer before it can become resistant—in other words, they try to use their strongest weapons first.

In addition to choosing the chemo drugs that show the best response rate based on research, your oncologist (cancer specialist) will also consider other factors when choosing your chemo drugs.

For example, your overall health and the side effects of the chemotherapy are also important to factor in.


While a person is having chemo, their oncologist will look at how well a treatment is working.

If the chemo drugs are killing the cells well, the cancer is chemosensitive. However, if the drugs are not working, the cancer is chemorefractory.

Cancer cells can be chemorefractory right from the start of treatment or become resistant to treatment over time.

A Word From Verywell

If you've been told that you have chemorefractory cancer, it does not mean there are no options left for your care. Your oncologist might switch you to a different chemotherapy regimen or a new type of treatment.

Researchers are trying to find ways to optimize cancer response rates and make it less likely that cancer will resist chemotherapy.

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12 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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