By Matthew Reiss, MSE, PhD, Manager, Precision Medicine & Navigation, GO2 for Lung Cancer 

This is the third blog post of our ongoing “Understanding Lung Cancer” series. This series aims to simplify the science behind lung cancer and help provide a deeper understanding of the disease. In the first and second parts, we introduced the basics of cells and explored how DNA damage can lead to cancer. We also discussed what drives cancer to grow and spread. This time, we’ll take a closer look at the role your immune system plays in cancer. We will also tackle how cancer cells avoid your immune system, and introduce the major types of lung cancer treatments used today, including approaches that are shaping the future of care.  

Your immune system: the body’s defense team 

Aside from the cell’s own means of identifying abnormal cells and preventing them from growing, your body has another line of defense: your immune system. The immune system is made up of cells, tissues, and organs that work together. It protects you from infections, repairs injuries, and removes cells that are damaged or no longer needed. One of its most important jobs is to identify and destroy cells that aren’t acting normally, including cells that could become cancer. Think of it like an army inside your body. It is always on the lookout for anything that doesn’t belong, ready to fight it off to keep you healthy. 

All cells have small “markers” or proteins found on their surface that tell the immune system whether they are healthy or not. If a cell seems abnormal, the immune system will target and destroy the cell before it becomes a bigger problem. 

So you may wonder: If the immune system can remove normal cells, why doesn’t it always stop cancer? 

How cancer cells avoid the immune system 

Cancer cells are clever. As they grow and change, they learn new ways to hide from or block the immune system. There are several ways cancer cells do this, but the most common ways include: 

  • Hiding their abnormal markers so that immune cells can’t recognize them 
  • Displaying markers on their surfaces that act as “don’t attack me” messages to immune cells 
  • Creating an environment around the cancer cells that weakens the immune response 
  • Growing so quickly that the immune system can’t keep up 

Cancer cells may use one or more of these methods to continue growing, even when the immune system tries to fight back. 

Applying what we’ve learned 

Now that we understand how cancer cells grow and how they avoid the immune system, we can focus on how current treatments work to address these challenges. 

In addition to surgery, which is a treatment where a surgeon aims to remove the cancer itself, there are several commonly used treatment approaches in lung cancer.

Chemotherapy: a long-standing tool in cancer care 

Chemotherapy, or “chemo,” works by attacking a cell’s ability to divide. It is known as a “systemic treatment,” meaning it travels through the bloodstream to affect the whole body, not just a specific, localized area. Unfortunately, this means that chemotherapy does not distinguish between healthy cells and cancer cells, which is why chemo often affects fast-growing cells throughout the body, including hair and blood cells. As a result, common side effects include hair loss and low blood cell counts. 

Because cancer cells divide so much faster than healthy cells, chemotherapy can still be a useful treatment option for many people. Improvements over the years have made many chemo treatments easier to tolerate. 

Radiation therapy: using energy to kill cancer cells 

Radiation therapy uses high-energy beams to damage the DNA inside cells, including cancer cells. This slows their growth or destroys them. It can be delivered from outside the body, aimed directly at the tumor. In some cases, radiation is given directly to the tumor inside the body itself.  

Because radiation has the potential to also affect healthy cells, it’s usually given in specialized ways that minimize its effect on healthy cells while directing most of the radiation to the cancer cells specifically. As a result, radiation usually affects fewer healthy cells than chemotherapy, and today’s techniques are more precise than ever before.  

Targeted therapy: targeting what makes cancer cells different 

We’ve previously talked about driver mutations. These are specific changes in the DNA of cancer cells that cause them to grow. Targeted therapies are treatments specifically designed to attack cells containing these driver mutations. Healthy cells are often spared, so people generally have fewer side effects. 

The same targeted therapy won’t work for everyone,  because not everyone will have a driver mutation that can be treated using targeted therapies. This is why biomarker testing is so important, specifically in non-small cell lung cancer (NSCLC). The targeted therapy used is matched to each person’s test results. 

There are many different kinds of targeted therapies, and new ones are being developed every day, but the 2 most commonly used targeted therapies in lung cancer are: 

  • Tyrosine kinase inhibitors (TKIs), which work by blocking the activity of the driver mutation in cancer cells to slow down or stop their growth. 
  • Antibody-drug conjugates (ADCs) that link targeting antibodies to chemotherapy-like drugs to deliver treatments directly to cancer cells. Think of it as “targeted chemo”. 

Immunotherapy: using your immune system to fight back 

Immunotherapies (sometimes called “IO”) are treatments that help the immune system recognize and attack cancer cells more effectively. Currently, immunotherapies fall into 2 main classes: 

  • Checkpoint inhibitors are a type of cancer treatment that blocks the cancer cells’ ability to hide from your immune system. This allows your immune system to better find and attack the cancer. 
  • T-cell engagers are a type of cancer treatment that helps T-cells (a type of immune cell) better connect to cancer cells. This connection helps the immune system attack the cancer more effectively. 

New treatments on the horizon 

Cancer research moves quickly. New treatments, including those that fall into the categories above, are always in development. But before they are used more widely, new treatments must first be studied in clinical trials to ensure they are safe and effective. Clinical trials give lung cancer patients a chance to try promising new treatments. They also help doctors learn what works best for future care. 

Everyone is different. The exact treatment your healthcare team recommends may include one or more of the treatments listed above. It’s important to speak with your healthcare team about which treatment is right for you. 

Coming up next: lung cancer risks and prevention  

In the final part of this series, we’ll explore the factors that can affect lung cancer risk. These include genetics, environment, and lifestyle choices. We’ll also discuss what individuals and communities can do to support prevention, early diagnosis, and better access to care.