Asymptomatic Importance and Controversy

You may have heard your doctor describe a condition as asymptomatic. The term asymptomatic literally means the absence of symptoms, in contrast to the term symptomatic, meaning symptoms are present. The importance of these terms go much deeper now, however, as doctors try to diagnosis disease while it is still in the asymptomatic phase. On the surface, this seems to a no-brainer. Find a disease before symptoms occur! Yet what if the condition would never have caused symptoms? Let's look at the definition of asymptomatic in several settings, the many different things it might mean if you have an asymptomatic problem, and then talk about the controversies lurking today.

Definition of Asymptomatic

The term asymptomatic means literally the absence of symptoms. It describes a condition that is present, but in which a person does not show any outward signs or symptoms of the disease.

Examples might include asymptomatic colon cancer in which a person has colon cancer but has not had any change in bowels or bleeding, asymptomatic lung cancer in which a person has not yet developed a cough or shortness of breathm or asymptomatic breast cancer in which a breast cancer can be seen on an imaging test (such as mammogram) but has not yet caused a lump or any other symptoms.

An asymptomatic infection may be one in which the bacteria or virus has invaded the body but has not yet caused a fever or any other symptoms.

The importance of finding an asymptomatic infection in at least some cases can be illustrated with HIV. If a person tests positive for HIV but does not have any symptoms, we usually describe this as being "HIV positive." When symptoms occur, however, such as opportunistic infections (infections with organisms that do not usually cause disease in people with a healthy immune system) or uncommon cancers, we usually use the term AIDS.

Uses of the Term in Medicine

Adding confusion to the definition of asymptomatic in medicine, there are two primary ways that the term is used:

  1. When someone has experienced and subsequently recovered from a disease such that they no longer have symptoms, they are considered asymptomatic. In this case, symptoms are no longer present.
  2. When someone has a condition (such as an infection or cancer) but does not yet have any symptoms. In this case, symptoms have yet to occur (if they ever will, that is).

In contrast, a condition that is present and which has symptoms would instead be called "symptomatic."


For most diseases, there is a period of time when the disease is present and asymptomatic before it becomes symptomatic. This is sometimes called the "asymptomatic phase." In fact, the majority of cancer screening tests are designed to detect cancer when it is in this phase—i.e. the cancer is present, but a person does not as yet have any symptoms due to that cancer.

If a condition is asymptomatic, it does not mean that it is not serious. It only means that, at the current time, the disease is not causing any symptoms. Even some advanced, stage 4 cancers may be asymptomatic for a period of time. The fact that ovarian cancer is often asymptomatic until well advanced is the reason that it has been coined the "silent killer"


If you have been told you have an asymptomatic illness or condition, don't panic. There are times when this is good information—when treating a disease that has not yet shown any symptoms can make a difference in your long-term health or even survival.

Yet there are many times when the discovery of an asymptomatic condition creates unnecessary fear—bringing to light a condition which would never be a problem. In these cases, some might even say "it's better not to know," as treating a condition which would never progress not only doesn't prevent disease in the future but brings on the complications and side effects of whatever treatment is used (not to speak of the emotional implications).

Different Meanings of Asymptomatic

An asymptomatic condition could refer to any one of a number of different situations.

An Early Sign of Something Serious That Can Be Heeded

The finding of an asymptomatic condition could be an early sign, which if heeded, could improve your long-term quality of life or survival. An example of this would be the early detection of lung cancer on CT screening. In this example, screening is recommended for people between the ages of 55 and 80, who have smoked for at least 30 pack-years, and continue to smoke or have quit in the past 15 years. In finding early cancers on CT—before any symptoms are present—it’s thought that lung cancer mortality in the United States could be decreased by 20 percent since screening often picks up cancers in the earlier more treatable stages of the disease. More recent studies suggest that this number is much higher, especially for women. Of course, screening may also result in one of the other scenarios below.

The asymptomatic finding could also mean a subclinical infection. An example of this would be a positive strep test in someone without symptoms, or a positive genital herpes test in someone without symptoms (or a positive HIV test.) Being aware of the asymptomatic infection could help reduce the spread of the infection.

A Sign of Nothing, Leading to Emotional Upset

The asymptomatic finding could be nothing—meaning that early detection will not lead to either an improved quality of life or greater survival—but the need to "work up" the finding may result in emotional turmoil.

A Sign of Nothing, Leading to Physical Harm

The asymptomatic finding could be nothing—again meaning that early detection will not lead to either an improved quality of life or greater survival—but the workup needed to evaluate the finding could actually cause more harm than if the finding had not been detected. An example could be the surgical risks related to a biopsy which shows a condition found not to be cancerous.

Good For Some, Bad For Others

The asymptomatic finding could result in improved survival for some people, but harm for others. An example is a controversy surrounding PSA screening in which testing may result in unnecessary workup and treatment (harm) for some while improving survival for others.

A Sign to Heed, But Only in Certain Situations

The asymptomatic finding could mean different things to different people. An example would be the finding of bacteria in urine tests. In pregnant women or people who have compromised immune systems, awareness of this finding can be advantageous and reduce the risk of serious disease, but for otherwise healthy people could result in unneeded treatment (and the possibility of side effects and adverse reactions to those treatments).

It may be impossible to know what the asymptomatic test really means for an individual patient. The finding could resolve (go away) or it could progress and cause symptoms.

Controversy in Screening

Lately, there has been considerable controversy concerning the use of screening tests, even cancer screening tests. While colon cancer screening and lung cancer screening for example, clearly save lives, it's still not certain whether prostate screening or even breast cancer screening plays a significant role in improving survival (weighing the benefits to some vs. risks to others).

Certainly, these screening tests increase the diagnosis of cancer, which is the heart of the current controversy in cancer screening termed overdiagnosis." It's often hard to know whether an asymptomatic condition will progress or will mean nothing. If it will progress, finding the condition can save lives. If it won't, finding the condition may result in overdiagnosis, overtreatment, and the potential risks related to diagnostic procedures and treatments.

It's also important to define prevention with regard to screening tests. While screening is often referred to as prevention, it is actually secondary prevention or early detection. Screening does not reduce the chance that a disease will occur, but is only designed to attempt to find the disease early. Primary prevention refers to measures used to avoid a disease in the first place.

Bottom Line

Certainly, there are conditions in which treatment of an asymptomatic condition clearly makes a difference, so any asymptomatic finding needs to be carefully and thoroughly discussed with your doctor. That said, it's important that people are aware that not all findings are meaningful. The term often used by medical residents is "red herrings." It's not uncommon to find conditions that are essentially meaningless, but since the condition has been found, a full work-up and potential treatment are then mandated. In being your own advocate in your health care it's imperative to be aware of this emerging problem—the downside of the excellent strides and advances we've made in the diagnosis of disease.

When talking to your doctor, ask a lot of questions. Examples include:

  • What are the chances that I will develop the disease for which I'm now asymptomatic?
  • What are the chances that nothing would happen if I ignored the finding (sometimes looking at statistics is helpful)?
  • Is there concern that this condition is overdiagnosed?
  • What would you do if you were in my shoes?

Pronunciation: A-simp-tow-mat-ick

Examples: Jaynie said they found her lung cancer early on a CT screening test when it was asymptomatic.

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