Does radiotherapy affect the immune system?

Radiotherapy, also known as radiation therapy, is a type of cancer treatment that uses high-energy particles or waves to destroy cancer cells by damaging their DNA. While radiotherapy can help reduce the size of tumors and slow down the spread of cancer, many patients wonder if it affects their immune system. In this article, we will explore whether radiotherapy has a negative impact on the human immune system.


The immune system is vital to protect our body from infections because it recognizes and neutralizes harmful microorganisms like bacteria, viruses or parasites before they cause damage. When someone undergoes radiotherapy treatments for cancer diagnosis, healthy tissue might be affected besides any malignant growths. Therefore lymphocytes – crucial white blood cells responsible for fighting foreign invaders – responding by becoming abnormally low reducing resistance against illnesses.

What Is Radiation Therapy?

Before exploring how radiation therapy affects the immune response let us cover what exactly happens during radiation therapy procedures:

It involves targeting high quantities of energy waveforms with gamma rays or ionizing radiations directly into areas where abnormal cell division occurs according to image mapping software-based plans which limits side-effects more than other recent modalities out there like High Intensity Focused Ultrasound (HIFU) or Proton Beam Therapy (PBT). Note that different types have diversely useful range elucidated in table 1 below:

Radiation Type Usage Cases
Gamma Knife Radiosurgery Brain Tumors
External-Beam Radiation Therapy Anywhere outside the Head
Internal Radiation Via Implants (Brachytherapy) Breast Cancer

Usually having one whole-body radio(radiation)^1 would equate delivery of roughly between five trillionth and forty billion Joules per gram (J/g), depending on intensity level set^2 after individual evaluation by specialists who employ computer tomography imaging scan techniques to measure tumor volume.

How Does Radiotherapy Affect The Immune System?

The impact of radiotherapy on the immune system appears to be complex and varies depending on factors such as type, dosage amount and frequency delivered in a specific course. While high doses of radiation can cause long-term suppression of immune function (1), low levels do not appear to produce significant weakening ^2. During treatment increased apoptosis occurs where cells are programmed for evident controlled death – which ensures tissues with diseased proliferation cannot survive longer and reproduce (DNA-damaged) products that circulate around organism^3.

Lymphocytes are crucial white blood cells responsible for fighting foreign invaders like bacteria, virus or parasite before they cause damage. When someone undergoes radiation therapy treatments due to cancer diagnosis healthy tissue will get affected alongside malignant growths; thus lymphocyte numbers decrease abnormally resulting in lower resistance against illnesses. Furthermore, the environment created during specialized therapy could give some tumours an advantage over healthy cells that normal defences may not succeed in countering their spread{5}.

Can Radiotherapy Increase Risk Of Infections?

Because radiotherapy weakens your immune system after sessions within six weeks but has gradually diminishing effects until 12 months post-treatment {9}. Patients receiving higher doses might require further medical care also antibiotic medication at times fend off infections taking every day precautions is essential when undergoing therapy regimens like staying away from heavily crowded places where exposure happens frequently to those people carrying contagious diseases patients have lowered ability detect extraneous elements easily making them vulnerable targets needing extra vigilance provided only by meticulous hygienic practices4.

Cases range between being extremely rare reaching up fifty percent more risk based survival rates interval it depends completely what exact route physicians take while delivering this procedure because outcomes can’t fully predictably cure everybody’s condition or turn out without unexpected complications originating elsewhere body similarly other variables outside doctor/professional control domain{5}.


In conclusion, Radiotherapy is an essential modality in treating cancer that matters a lot. It can have both positive and negative impacts on the immune system affecting individuals differently – which shows it more challenging to define general conclusions regarding this subject accurately. Understanding how the therapy works empowers you with necessary knowledge thus allow specially trained healthcare practitioners coordinate patient care precautions accordingly before treatment administration is ever started so one knows what they are getting into — be sure ANY decision made counts towards the overall goal of optimal recoveries free from health problems over time {10}.