Radiation: Does it cause cancer or treat it?

July 02 07:14 2025 Print This Article

Summary

Radiation therapy is one of the popular options under cancer treatment. The reason being – its efficacy in destroying tumour cells. However, there used to be a small risk of other primary-cancers developing in the long run, due to this therapy. But in the last couple of decades, radiation therapy has become more advanced and sophisticated. This has hugely reduced the risk of developing new cancers over time. Even if there is a very small probability of risk that exists, radiation is still worth it, say doctors. In this article, we will understand why.

Introduction: What is Radiation 

‘Radiation’ is a generic word for the emission of energy in any form – whether it is light, heat, sound, wind energy, cosmic rays, static energy, etc. However, ever since radioactivity and microwaves were discovered or demonstrated by some of the legendary scientists of the 20^th century, the word Radiation has been adopted to indicate a certain set of, or types of – energy sources. Wilhelm Conrad Röntgen discovered Radiation. Some of these sources of energy are used in radiation therapy, which is one of the options for cancer treatment.

Sources of Radiation 

Natural 

The universe is full of naturally occurring radiation sources. Ultraviolet rays of the sun, cosmic radiation (experienced by astronauts), Radon gas and radioactive metals are naturally occurring sources of radiation. Thorium sands of Kerala are another example of naturally occurring radioactive materials. Radon is a gas formed when Radium, one of the radioactive metals breaks down. It is found in rocks and certain minerals, where Radium used to be present previously and has been breaking down over time. Radon gas can accumulate in walls, floors and building spaces. Long term exposure to Radon gas increases the risk of lung cancer (it is a good idea to get your home tested for radon levels).

Man-made

• All radio-active metals emit harmful radiation. These metals are used in nuclear-power plants and for making nuclear weapons. Employees of facilities where these metals are used are at high risk of radiation exposure. The accidents at Chernobyl nuclear-plant in Russia and Fukushima-Daichii nuclear-plant in Japan have exposed thousands of people in the vicinity to radiation. The aftermath of atomic bomb-blasts at Hiroshima and Nagasaki are well-known. Incidentally, mildly radioactive metals or their compounds are used in medical diagnosis (example – barium drink).
• Similarly, Radio Frequency waves or microwaves of different wavelengths are also treated as radiation that can cause varying extents of harm to human beings. These are used in Radars, cell-phones and Wi-Fi Routers.
• Other than the above, X-rays, gamma rays, alpha particles, beta particles, protons, neutrons and electrons have all been harnessed by science for various purposes. For example, these are used extensively in imaging technologies for medical diagnosis, such as X-ray, CT scan and MRI scan.

Also Read: What is Radiotherapy? – What You Need to Know

Types of Radiation

All the above types of radiation can be broadly divided into two types:

Ionizing radiation: These forms of radiation have enough energy to dislodge electrons from an atom and convert it into an ion, hence the name. Radioactive metals used in nuclear-power plants and nuclear weapons, Radon gas, special rays used for cancer treatment and in medical-imaging devices – are all sources of this type of radiation.

Non-ionizing radiation: These forms of energy are not so intense that they can create ions out of atoms. However, they can cause changes in the vibrational and rotational energy of molecules. These changes are then dissipated as heat, which can be mild to moderate to intense heat. RF waves and microwaves used in radar, RF devices, Wi-Fi routers, cell-phones, as well as UV light from the sun – are all sources of this type of radiation.

Why is Radiation used in cancer treatment? 

As mentioned above, ionizing radiation can create ions out of atoms, in non-living matter. In living matter, they can cause major chemical disruptions that are powerful enough to change the DNA or genetic-code of a cell, or group of cells. Further, these genetic changes are permanent. This point becomes useful in cancer treatment.

When radiation is applied to a tumour or a lump of cancerous tissue, there are changes being forced on to the genetic code of these cancer cells. In the absence of a correct code or the original code, these cells do not understand how to replicate (multiply or divide). In the process, they start dying out slowly. So effectively, the cancerous tissue is destroyed.

So today, Radiation therapy is being used to:

• Shrink tumours before other cancer treatments like a surgery becomes necessary (this is called a neo-adjuvant therapy).
• Destroy any cancer cells that are still remaining after definite surgery (called ‘adjuvant therapy’).
• Along with chemotherapy where in Radiotherapy is given daily and chemotherapy given every week or 3-weekly (concurrent chemo radiation)
• Kill cancer cells that come back after the previous treatment, because some of them were circulating in the blood and settled down at the spot to grow again (this is called a cancer relapse)
• Destroy benign or non-cancerous tumours that are causing some symptoms

Can Radiation therapy cause another primary cancer? 

While radiation can destroy cancer cells as explained above, they can also destroy healthy cells. This is because, healthy cells in the vicinity of the cancerous tissue also get exposed to some of the radiation. In the process, their DNA also goes through changes or genetic mutations. Over time (and not immediately), these mutations can lead to a new cancer (called a second primary-cancer) in a nearby or another part of the body. So how has this outcome been handled by medical treatments for cancer or other ailments?

In the past

Before the risks of radiation was understood, radiation was used both for treating cancer and other ailments. This led to new cancers developing over time. For example:

• Radiation used to treat peptic ulcer disease (PUD) was linked to a higher risk of stomach and pancreatic cancers in the patient.
• Radiation used to treat ringworm of the scalp was linked to a higher risk of basal-cell skin cancers.
• Radium injections used to treat ankylosing spondylitis was linked to a higher risk of leukaemia, bone sarcoma, and other cancers.
• Radiation used to treat some benign head and neck conditions was linked to a higher risk of cancers of the salivary gland, thyroid, brain and spinal-cord.

Even imaging tests have been linked to new cancer development at a later time in life. For example:

• Women who have had several sessions of fluoroscopy (for tuberculosis treatment) as a teenager or early adult had a higher risk of breast cancer several years later.
• Similarly, teenage girls and young women who have had several x-rays of the spine to monitor scoliosis showed a higher risk of breast cancer in later life.
• People who have had certain types of dental x-rays every year showed a higher risk of a benign tumour of the brain called meningioma.
• Children who have higher doses of radiation during CT scans showed a higher risk of leukaemia and brain tumours.

Now, in all the above cases, the higher risk did not mean that the person developed that particular cancer. Further, the risk of radiation creating another primary cancer depends on various factors such as:

• The dose or intensity of radiation
• The part of the body that is being treated with radiation (some parts are more vulnerable than others)
• The age of the person (younger people are at higher risk because their immune systems may not be that strong)
• The use of other cancer treatments such as chemotherapy along with radiation
• Genes: some people are more prone to genetic mutations than others, due to radiation

In the present

In the last couple of decades, since the medical community understands the risks from radiation, radiation therapy has advanced several folds. According to radiation oncologists, the intensity of radiation, the delivery mechanism used, the ability to focus radiation on cancer cells while isolating them from healthy cells, have all improved, or become more sophisticated. This has significantly reduced the risk of developing new cancers with time. At this juncture, it’s useful to understand how radiation therapy is done today. We have principles, quality assurances and regulatory boards to guide in maintaining close intensity of radiation therapy.

Types of Radiation therapy 

There are 2 broad types: external beam radiation therapy and internal radiation therapy.

External Beam Radiation Therapy (EBRT)

In this, the radiation source is kept outside the body and the radiation focused on that part of the body where the cancer is present. Type of radiation used is X-rays, electrons or protons. The different forms are:

• 3D conformal radiation therapy: This uses CT scans and computer software to create an image of the tumour which is used as a guide while directing radiation.
• Intensity-modulated radiation therapy (IMRT): This delivers higher doses of radiation to the centre of the tumour and lower doses to edges, where healthy tissues are present.
• Arc-based radiotherapy: A variation of IMRT where the energy beams form a rotational arc-like pattern.
• Image-guided radiotherapy (IGRT): Here, a low-dose X-ray or mini-CT scan is done before each session, which helps re-align the radiation more precisely every time.
• Particle therapy: This uses radiation therapy that consists of protons instead of photons or X-rays.
• Stereotactic radiosurgery, such as Gamma Knife surgery: uses high-intensity radiation with surgical precision to destroy small tumours in the brain.
• Stereotactic body radiation therapy (SBRT): Similar to the above, but where the cancer is outside the brain.
• Intraoperative radiation (IORT): This is done during surgery and also after surgery to destroy remaining cells that cannot be surgically removed.

Internal radiation therapy (IRT)

According to radiation oncologists, here, the radiation source is injected into the body, as close to the cancer site as possible. This is used to treat small cancers of the head, neck, prostate, cervix, breast and uterus. The radiation source may be solid or liquid, so there are 2 types:

• Brachytherapy: In this, a small radioactive ‘seed’ is implanted inside or beside a tumour using various techniques. This focuses the radiation on the tumour while sparing healthy cells.
• Systemic therapy: In this, liquid radioactive material is flushed through the blood to seek out and destroy cancer cells, in a targeted fashion.

Real Stories. Real Healing.

Thank you Kauvery hospitals Radiation therapy team. I had my radiation therapy at this Place for 25days.I am under the care of Dr Andrew C Fenn. He is so patient friendly, warm and gentle. The staff are all extremely friendly towards me. God bless you all.
– Shobana Padmanabhan

Especially the radiation treatment has been given to the patient by the team is very excellent level. It show’s that’ their treatment has not compared with others. There team are unique in caring with lots of love to each patient without any partiality.
– Prabhas

Outlook 

What does all this imply? That, while previously, radiation could both cure and cause cancer, today, its only curing cancer. Advances in radiation therapy have reduced the risk of developing newer cancers over time, drastically. Even if there is a very tiny probability of new cancers developing, radiation therapy is still worth the risk. That is the unanimous verdict of both the medical and scientific communities.

To learn more or seek guidance on radiation therapy, contact Kauvery Hospital, a leading healthcare provider in Tamil Nadu. With branches in Chennai, Hosur, Salem, Tirunelveli, and Trichy, our dedicated oncologists are ready to provide you with personalized care and comprehensive cancer treatment options.

Got Questions About Radiation Treatment? We’ve Got Answers

Can radiation therapy cause cancer?
Yes, though rare, radiation therapy may increase the risk of developing a second cancer years later. However, with today’s advanced, focused techniques, this risk is very low and the benefits of treating the existing cancer far outweigh potential long-term risks.

How does radiation therapy work in treating cancer?
Radiation therapy uses high-energy rays to damage the DNA of cancer cells. This stops them from growing and multiplying, eventually destroying them. It’s a common, effective treatment for many types of cancer.

Is radiation therapy painful?
No, the therapy itself is painless. However, some patients may experience side effects such as fatigue or skin irritation in the treated area, depending on the type and dose of radiation used.

What are the modern types of radiation therapy?

There are two main types:

• External Beam Radiation Therapy (EBRT) – like IMRT, IGRT, SBRT
• Internal Radiation Therapy – like brachytherapy and systemic therapy.

Modern technology ensures precision and minimal damage to healthy tissues.

Who decides if radiation is the right cancer treatment?
A radiation oncologist, often as part of a multidisciplinary cancer team, evaluates the type, location, and stage of the cancer to decide if radiation therapy is appropriate for a patient.

Is radiation therapy safer now than in the past?
Absolutely. Advances in imaging, planning, and targeting have made radiation therapy far more precise, significantly reducing exposure to surrounding healthy tissues and minimizing long-term risks.

Kauvery Hospital is globally known for its multidisciplinary services at all its Centers of Excellence, and for its comprehensive, Avant-Grade technology, especially in diagnostics and remedial care in heart diseases, transplantation, vascular and neurosciences medicine. Located in the heart of Trichy (Tennur, Royal Road and Alexandria Road (Cantonment), Chennai (Alwarpet, Vadapalani & Radial Road), Hosur, Salem, Tirunelveli and Bengaluru, the hospital also renders adult and paediatric trauma care.

Chennai Alwarpet – 044 4000 6000 • Chennai Vadapalani – 044 4000 6000 • Chennai Radial Road – 044 40504050 • Trichy – Cantonment – 0431 4077777 • Trichy – Heartcity – 0431 4003500 • Trichy – Tennur – 0431 4022555 • Hosur – 04344 272727 • Salem – 0427 2677777 • Tirunelveli – 0462 4006000 • Bengaluru – 080 6801 6801