What Does the Term Response Rate Mean When it Comes to Cancer Treatment?

ByPrimary Researcher

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Executive Summary

  • The term response rate is used in cancer research studies and articles on cancer treatments.
  • In this article, we explain what this term means.

Introduction

Articles on cancer will frequently use the term “response rate” but usually do so without defining the term. Part of the problem in interpreting the effectiveness of cancer treatments is that oncologists, researchers, and cancer centers use words that do not measure the outcome but instead focus on an intermediate endpoint.

This article will explain what response rate means and why it is misleading.

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What is the Response Rate?

The term response rate is covered in the article What Is Palliative Chemotherapy?

Chemotherapy may be helpful in shrinking the cancer, improving or completely eliminating distressing symptoms caused by the cancer for a period of time and helping you live longer. The use of chemotherapy in these situations is called palliative chemotherapy.

This is deceptive because one of the favorite endpoints of cancer researchers and pharmaceutical companies is shrinking tumors — which has not been shown to lead to longer expected life. Furthermore, chemotherapy does not improve or eliminate distressing symptoms but has harsh adverse effects.

Now let us see what this article says about response rate.

Response Rate refers to the likelihood that your cancer will improve from the treatment. A Response Rate of 30% means that if 100 patients like you were treated, 30 patients would have their cancer shrink by one-half or more. For some cancers, the term response rate can be expanded to include those patients whose cancer did not shrink, but also did not grow. Talk to your oncologist to understand exactly how he/she is using the term response rate for your cancer.

And this is the problem. First, the response rate does not have anything to do with extended life due to the treatment, and even within what is being measured (in this case, tumor growth), it can still mean several different things.

When the term “response rate” is used, the information provider is trying to move the target away from extended life or increased curative effect of treatment to something intermediate that sounds good but is most likely not related to a better outcome.

Now let us move to the following term that is used.