Your immune system plays a vital role in maintaining your health. Although some cancers are caused by genetic mutations, some other factors like old age and a weakened immune system can also play a significant role in causing the disease.
Your immune system plays a vital role in maintaining your health. Although some cancers are caused by genetic mutations, some other factors like old age and a weakened immune system can also play a significant role in causing the disease.

Every year, more than eight million people die from cancer. New studies and ongoing research regarding cancer prevention have helped improve treatment.

However, many questions are still unanswered. One of them is whether a weak immune system can cause cancer. Your immune system plays a vital role in maintaining your health. But if you have weakened immunity, could it increase the risk of cancer? 

Cancer is caused by genetic changes that lead to uncontrolled cell growth. This genomic instability leads to tumor formation. Although some cancers are caused by genetic mutations, some other factors can also play a significant role in causing the disease. 

For example, drinking alcohol and smoking tobacco can cause cancer. These risk factors are avoidable, but other important risk factors are not. These include old age and a weakened immune system.

What is the immune system?

The immune system is your body's defense mechanism that protects you from diseases. It's a system of biological processes that can detect various invading pathogens like bacteria, viruses, parasites, or even cancer cells. 

Anything that is not a natural part of an organism's healthy tissue is recognized and destroyed by the immune system. This way, your immune system protects your body against illnesses and infections.

What can weaken your immune system?

Some people are born with a weak immune system. On the other hand, aging can weaken your immune system, as can some unhealthy habits. Here are some factors that can contribute to a weakened immune system:

  • Unhealthy eating 
  • Lack of sleep 
  • Nutritional deficiencies 
  • Too much stress 
  • Metabolic diseases
  • Smoking 
  • Drinking alcohol

How does a weak immune system cause cancer?

Genetic mutation plays a significant role in causing cancer. As you age, the frequency of mutations increases and your immunity decreases. With increased mutations and weakened immunity, you are at a greater risk of getting cancer.

A less effective immune system makes you more susceptible to illness. The thymus gland, a part of your immune system, develops T cells. These play an essential role in building your immunity. The deterioration of your thymus gland causes it to produce fewer T cells, which weakens your immune system.

When cancer cells show up in your body, your immune system usually kills them before they can form a tumor. First, the T cells scan your body for cancer cells. Then, they locate the cancer cells in your body and destroy them.

When your immune system is weak and produces fewer T cells, they fail to scan your body for cancer cells. As a result, the abnormal cells are able to grow uncontrollably and form a tumor.


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Do cancer treatments affect your immune system?

Some cancer treatments rely on your immune system to treat cancer. Immunotherapy is one such treatment. Different types of immunotherapy may boost or reduce your immune response to fight the cancer cells more efficiently. Some types of immunotherapies are:

  • Monoclonal antibodies: These are able to recognize proteins on the surface of the cancer cells. The antibodies then attack the abnormal cells. 
  • Vaccines: Some vaccines help boost immunity so your immune system can efficiently recognize and attack cancer cells.
  • Cytokines: These are small proteins that help boost your immune system by facilitating communication between your immune system's cells.
  • CAR T-cell therapy: This is also called adoptive cell transfer. It changes the genes in your white blood cells to help them fight cancer. 

The effects of cancer on the immune system

Cancer makes the immune system weak as it spreads into the bone marrow. The bone marrow is responsible for making blood cells that fight infection and invade foreign particles such as viruses, bacteria, parasites, etc. 

Cancer stops the bone marrow from making these blood cells. This is particularly common in leukemia and lymphoma

Certain cancer treatments can also weaken your immune system because they reduce the number of white blood cells. These treatments include: 

  • Cancer treatment drugs
  • Chemotherapy
  • Radiotherapy
  • Steroids

The bottom line

If you wish to take a more active role in boosting your immune system, there are some things you can do. For example: 

  • Eat certain foods, like elderberries and yogurt 
  • Minimize daily stress
  • Spend time with pets and loved ones
  • Take a multivitamin
  • Exercise
  • Get enough sleep

Aging is not the only factor that weakens your immune system or puts you at risk of cancer. Many other factors can weaken your immune system as well. If you experience high levels of stress, stomach aches, or exhaustion on a regular basis, it's a good idea to consult a doctor.

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Medically Reviewed on 11/29/2021

American Psychological Association: "Stress weakens the immune system."

Cancer Research UK: "The immune system and cancer."

eLife: "Rejection of immunogenic tumor clones is limited by clonal fraction."

National Cancer Institute: "Risk Factors for Cancer."

National Library of Medicine: "Alcohol and the Immune System," "Diet and Immune Function," "Impact of Obesity and Metabolic Syndrome on Immunity," "Impacts of cigarette smoking on immune responsiveness," "Roles of the immune system in cancer: from tumor initiation to metastatic progression."

Mayo Clinic: "Lack of sleep: can it make you sick?"

Proceedings of the National Academy of Sciences of the United States of America: "Thymic involution and rising disease incidence with age."

World Health Organization: "Cancer."