How Cancer Treatments Affect Your Immune System and What You Can Do About It

Cancer treatment is an essential step in the fight against cancer. Whether it’s chemotherapy, radiotherapy, surgery, immunotherapy, or a combination of these, each therapy aims to destroy cancer cells and halt their growth. While these treatments are powerful, they can also impact your immune system; sometimes weakening it, sometimes activating it to help fight the disease.

In this article, we’ll explore how different cancer treatments interact with your immune system, what that means for your health, and how you can support your immune defences during your cancer journey.

Chemotherapy: A Double-Edged Sword

Chemotherapy is one of the most widely used treatments for cancer. It targets rapidly dividing cells—a hallmark of most cancer cells. However, some healthy cells, such as those in your bone marrow, mouth, gut, and hair follicles, also divide quickly. As a result, chemotherapy can damage these healthy cells, including those that produce white blood cells.

One of the most important impacts of chemotherapy on your immune system is neutropenia, a drop in neutrophils (white blood cells that fight infection). This makes you more vulnerable to bacterial, viral, and fungal infections, especially seven to fourteen days after a chemotherapy cycle when white blood cell levels are lowest. Additionally, chemotherapy can also affect the integrity of the skin, leading to dryness, rashes, and increased sensitivity. Understanding how chemotherapy impacts skin health is essential for managing these side effects effectively. Patients should work closely with their healthcare team to develop a skincare regimen that minimizes discomfort and promotes healing.

To protect yourself:

• Practise good hand hygiene
• Avoid large crowds
• Monitor for signs of infection, such as fever or chills

Despite these risks, chemotherapy remains a critical tool in fighting cancer. With the right precautions and guidance from your healthcare team, you can navigate these challenges and benefit from treatment.

Radiotherapy: Local Effects with a Wider Impact

Radiotherapy, or radiation therapy, uses high-energy rays to kill cancer cells. Unlike chemotherapy, it’s usually focused on a specific tumour site. Radiotherapy can also affect nearby healthy tissues, including immune cells in the treated area. For example, radiotherapy to the chest can impact lymph nodes, which are important centres of immune activity.

Interestingly, radiotherapy can sometimes stimulate the immune system. When cancer cells die from radiation, they release antigens that can attract immune cells—a process called immunogenic cell death. Some treatments even combine radiotherapy with immunotherapy to enhance this effect.

Surgery: The Immune System’s Silent Partner

Surgery is often the first step in removing solid tumours. However, surgery itself is a form of stress on the body. Stress hormones like cortisol can temporarily suppress immune function. Wound healing also diverts immune resources away from fighting cancer.

Modern surgical techniques have reduced these effects, but it’s still important to understand how surgery may affect your immune system. Discuss strategies for recovery and infection prevention with your healthcare team.

Immunotherapy: Unleashing Your Body’s Natural Defences

Immunotherapy has revolutionised cancer treatment. Instead of directly attacking cancer cells, it empowers your immune system to fight the disease.

• Checkpoint inhibitors block the signals that cancer uses to hide from your immune system, letting T-cells attack.
• CAR T-cell therapy modifies your T-cells to better target cancer.

While powerful, immunotherapies can also cause the immune system to attack healthy tissues, leading to autoimmune-like side effects that may affect the skin, gut, liver, or lungs. Your healthcare team will monitor you closely for these reactions.

Targeted Therapies: Precision Meets Immunity

Targeted therapies focus on specific molecules involved in cancer growth. They generally have fewer side effects than chemotherapy, but can still affect immune cells. Some targeted therapies might suppress immune activity, while others could cause inflammation or autoimmune issues.

Your doctor will carefully balance the benefits of treatment against these risks, adjusting your plan as needed.

Monitoring and Supporting Your Immune Health

Your healthcare team will monitor your immune health with regular blood tests to check levels of white blood cells and other key immune markers. For example, measuring PD-L1 on tumour cells can help determine whether checkpoint inhibitors will work for you.

Key strategies for supporting your immune system:

• Nutrition: Eat a balanced diet rich in fruits, vegetables, and lean proteins.
• Exercise: Gentle activities like walking or yoga can help maintain immune function.
• Sleep: Aim for 7-9 hours of sleep each night.
• Stress Management: Practice deep breathing and meditation, or talk to friends and family.
• Infection Prevention: Wash hands regularly, avoid sick contacts, and ask about vaccinations.

Working with Your Healthcare Team

Your oncologist, nurses, and other specialists are your partners in managing your immune health. Don’t hesitate to ask:

• How will this treatment affect my immune system?
• What signs of infection should I watch for?
• How can I support my immune health during treatment?

Conclusion

Cancer treatments are essential weapons against cancer, but each interacts with your immune system in unique ways. Understanding these effects empowers you to protect your immune defences, reduce the risk of infection, and stay strong throughout your treatment journey. By learning about how the immune system combats cancer, patients can make informed decisions about their care. This knowledge can also lead to proactive measures that support overall health, such as optimizing nutrition and managing stress. Ultimately, a well-supported immune system is crucial for enhancing the efficacy of cancer treatments and improving long-term outcomes.

Your immune system is not just a bystander—it’s an active ally. By working closely with your healthcare team and taking steps to support your immune health, you can build a foundation for resilience and recovery.

Edited by: Macey Tocher