Progressive Disease and Cancer

Physicians use many terms to describe the progress of a cancer or its response to treatment, one of which is progressive disease. Progressive disease means what the term implies, that a cancer is getting worse, but these terms are used to explain exactly how much worse a cancer appears to be.

There are many reasons, in turn, why a cancer could be labeled as being progressive, and your prognosis may vary significantly depending on which of these underlying processes is at play.

What do you need to know about the different terms used to describe the changes in a cancer or response to treatment, and why are these terms used? Let's take a look at some of this confusing terminology so you can understand exactly what your oncologist is saying.

It's also important to note up front that, with the new types of treatment we have, progressive disease is not always a sign that a treatment is not working.

Defining Progressive Disease

Progressive disease is a term that describes a disease that is progressing or worsening. With cancer, progressive disease is defined as at least a 20 percent growth in the size of the tumor or spread of the tumor since the beginning of treatment. In other words, if the size of a tumor is 20 percent larger on a scan it would be called progressive disease. You may also be told you have progressive disease if the size of your primary tumor has not changed significantly in size, but you have new metastases.

Historical Meaning of Progressive Disease

If you have been told you have "progressive disease" it can mean one of 3 things:

The Tumor is Growing

As noted, an increase of 20 percent in size is considered progressive disease. Keep in mind that measurements looking at the increase in a size of a tumor are approximations, and not so accurate. A tumor that is classified as being progressive disease has likely grown substantially or it would be called stable disease.

The Tumor is Spreading

Your tumor has spread to new regions or more evidence of cancer is seen in any area of previous spread.

Why Progressive Disease May Not Mean Treatment Failure

At the current time, the criteria for progression is likely changing. While once, having progressive disease meant one of the situations above, that's no longer necessarily true.

An example is with the use of immunotherapy medications. Rarely, people who have very good responses to immunotherapy drugs initially appear to have progressive disease. The term that is used to describe this situation is pseudo-progression, or the appearance of progression when a tumor has not actually progressed.

On imaging studies, a tumor may be appear to be larger or appear to have spread to new regions. When biopsies have been done, however, the apparent increase in size of the tumor is actually due to the presence of cancer-attacking lymphocytes surrounding the tumor. In some cases, the tumor is no longer present at all. The same may be true with metastases.

Due to being surrounded by immune cells, a tumor that could not previously be seen on an imaging study may now be seen because of the presence of immune cells.

What this means is that it's important to talk to your oncologist carefully if you've been told that you have progressive disease, and not give up hope.

Next Steps

Your healthcare provider may use the term progressive disease as an indicator of when to choose a new treatment. For example, it may be time to switch to a second-line treatment instead of continuing the first-line treatment. The term may also be used as part of a clinical trial to indicate an inadequate or poor response to an experimental treatment.

Other Terms Describing the Current State of a Cancer

There are several other terms that you may hear in reference to your cancer. These can include:

Stable Disease

Stable disease means that a cancer hasn't changed significantly in either direction. In other words it hasn't grown significantly or decreased significantly in size. Stable disease can actually be a positive sign during treatment. Generally, a tumor would be expected to continue growing. If it hasn't grown, it can mean the treatment is working even if hearing there is no change feels discouraging.

Complete Response

If you have a complete response it means that all detectable signs of a tumor are gone. This may also be called a complete remission or NED (no evidence of disease). In a complete response, there will be no indication of cancer present on a physical exam or on imaging studies such as a CT scan, MRI, or PET scan. It does not mean that a cancer is cured, as there may still be microscopic cells and regions of cells present that are not detectable with our current studies. 

Partial Response

A partial response means that a tumor has decreased in size by 30% but there is still detectable disease present. This may also be referred to as a partial remission. The meaning of a partial response could be very good or bad, depending on the situation.

Objective Response

The term objective response most often refers to either a partial response or a complete response to a treatment.

Clinical Benefit

Clinical benefit is an informal term referring to a situation where, as long as the cancer is prevented from getting worse, the patient is benefiting. It does not mean a patient has had a response, simply that they have derived a benefit because the cancer has not gotten worse.

Bottom Line

If you've learned you have progressive disease you may be feeling depressed. It's always hoped that a tumor will respond to treatment. If you have progressive disease, however, it does not mean that there are no options left.

Finding you have progressive disease may simply mean that it's time to switch to another line of treatment which will hopefully be more effective. With the use of targeted therapies becoming more common this will become clearer.

Often one drug is used to control the cancer until the tumor becomes resistant to that drug. This does not mean that the cancer is then untreatable. It may only mean that it's time to change to another medication to control the growth.