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Lung cancer and the immune system

The immune system is one of the largest, best-ordered systems in the human body, made up of organs, cells, and other substances that all work together to protect and defend us from foreign invaders and internal threats.

But what if the threat to our body is, in fact, cancer?

Over the years, researchers have focused their attention on one of the body’s most sophisticated systems—the immune system—and its potential ability to respond to cancer. This research has helped us better understand the way the immune system works—as well as the way cancer behaves.


How does our immune system work?

The immune system is always on active patrol for foreign invaders—like germs and viruses. Most of the time, our immune system does a fine job of keeping us healthy and preventing infections from getting in or spreading. But sometimes problems with the immune system can lead to infection or illness. For instance, an external threat (like a virus, bacteria, or parasite) can successfully invade and make you sick. Or an internal threat, like cancer cells, can begin to grow and the immune system doesn't recognize them as a threat or can't attack them fast enough.


Immune System

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We rely on 24/7 immune system surveillance

Since the immune system is always on active patrol for foreign invaders—like germs and viruses—you would think it could detect cancer cells, too. Truth is the immune system is better at recognizing cells from germs and viruses than recognizing cancer cells. That's because external threats look different from cells that belong in the body, and this allows them to be spotted as "foreign" and therefore attacked. Cancer cells, on the other hand, are internal cells that actually look a lot like normal cells with fewer clear differences. Because of this, the immune system may not always recognize them as "foreign"—and may not go into attack mode.


What provokes an immune response?

So how does the immune system work for us? When the immune system identifies a threat, either external or internal, it creates an "immune response." That basically means the immune system goes into attack mode to destroy the invader.

There are different types of immune responses

The first line of defense in the immune response is referred to as "innate immunity"

Innate immunity responses are the body's basic defenses. Examples include:

  • mucus, which traps bacteria and small particles
  • skin, which forms a protective barrier around us
  • enzymes in our tears and saliva, which break down infectious bacteria
  • stomach acid, which can destroy many varieties of bugs

The next type of defense is an "adaptive immune response," which is a more specific, sophisticated defense

In an adaptive immune response, the immune system uses its long "memory"—that is, its ability to recognize invader cells and go into attack mode when it encounters these cells again. When its memory is activated, the immune system sounds the alarms for T cells and other fighter cells to identify and attack specific invader cells.

  • T cells help in the adaptive immune response

T cells play a big role in an adaptive immune attack and contribute to the response in 2 ways: some T cells direct other cells, supervising and regulating the immune response. And some T cells attack unwanted cells directly.

  • Antigens

Some foreign cells wear a substance (usually a protein) called an "antigen" on their surface (think of a brightly colored hat), making it easier for T cells to spot them and destroy them. Cancer cells wear antigens as well—but sometimes, for complex reasons, it's harder for the immune system to recognize them.

Cancer and the immune system

When the immune system is working properly, an immune response can lead to the destruction of anything containing the antigen, such as germs or cancer cells. When the immune system doesn't work hard enough, this can result in infection. And when immune surveillance breaks down, this can result in cancer cell progression.

Scientists are working to develop potential cancer treatments that target the immune system. This field of study is referred to as immuno-oncology.

Did you know that your immune system is attempting to identify and kill cancer all the time?

One of the roles of the immune system is to identify cancerous and/or precancerous cells and eliminate them before they can cause harm. This concept is known as "tumor immune surveillance." But even in the presence of a functioning immune system, tumors can develop. This is thought to happen when the immune surveillance breaks down or is overwhelmed.


Everyone's cancer experience is different. But challenging moments are common and should be expected. Learn how to prepare now for any potential obstacles.

NEXT: Facing Potential Obstacles

NEXT: Facing Potential Obstacles


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