The Difference Between Radiotherapy and Chemotherapy

27th April 2016  

With cancer still being one among the leading killer diseases of the day, various treatments are used to suppress the disease. The administration of a certain treatment depends on what type of cancer a person has, how advanced the cancer is, the overall health and preferences of the patient.

There are too many types of cancer. Fortunately, some of them can be prevented through leading a healthy lifestyle. Immunisation is another way of preventing certain cancers.

radiotherapy vs chemotherapy

Some cancer patients can have a single treatment while others have combined treatments, for instance, surgery with radiation therapy and/or chemotherapy.

Another option can be clinical therapies. A multidisciplinary team (different kinds of doctors) frequently work hand in hand to come up with a strategy, which integrates different types of treatments for a patient.

Radiotherapy and chemotherapy are seen to be among the most effective as well as common cancer treatments that doctors recommend. Most people do not know the difference between radiotherapy and chemotherapy, specifically those who have never been treated using either of the two.

Continue reading to understand the difference between the two.

Radiotherapy Vs. Chemotherapy


Chemotherapy also referred to as chemo, is a form of cancer treatment, which utilises chemical substances, one or more anti-cancer drugs to kill cancer cells.

Radiation therapy, also known as radiotherapy is, on the other hand, a cancer treatment approach, which utilises high radiation doses to kill cancer cells as well as shrink tumours.

X-rays make use of radiation at low doses to see inside the body, as with broken bones or teeth x-rays.

cancer treatments


Radiation focuses on damaging the DNA of only the cancer cells. The damage of DNA happens as a result of one or two energy forms: photon or charged particle.

Such damage is either indirect or direct ionisation of atoms that form the DNA chain, particularly hydroxyl radicals that then damage the DNA. Radiation minimises tumours as well. The Approach is also referred to as X-ray therapy, irradiation or radiotherapy.

Chemotherapy makes use of the bloodstream to attack cancer cells. Most chemotherapeutic drugs act by impairing cell division, effectively aiming at fast dividing cells.

The drugs are referred to as cytotoxic because they cause damage to the cells. Such drugs prevent mitosis through different mechanisms, for instance, damaging DNA as well as inhibition of cellular machinery that participate in cell division.As a result, cells cannot duplicate themselves. Inducing apoptosis (a programmed kind of cell death) and is among the theories as to why such drugs kill the cancer cells.

The problem is that their action does not only target cancer cells. One limitation of such drugs is the inability to differentiate between cancerous & non-cancerous cells. Eventually, they harm both of them.


Radioactive therapy can be administered in two ways: internal radiation therapy or external beam radiotherapy.

signs of skin cancer

Internal Radiation therapy

Here, a radiation source is placed inside the body. Such a radiation source may be in a liquid or solid form. If the source is solid then such therapy is known as brachytherapy. In such a treatment, radiation is placed in the body in or near to the tumour. Such radiation is in the form of ribbons, seeds or capsules.

Liquid radiation is administered via an IV line. It travels through the body trying to find and kill cancerous cells.

External Beam Radiotherapy

Is a form of radiation coming from a machine that aims the radiation to your cancer.

Such a machine can be huge and noisy. It does not make conduct with the patient, however, it moves around the patient sending radiation from different directions to a part of the body.

This form of therapy treats a particular part of your body. For instance, a patient with lung cancer will only have radiation on the chest and not the entire body.

Chemotherapy, on the other hand, can be administered in different ways including the following:

  • Oral- chemo can come in liquids, pills, or capsules to swallow.
  • Injection- chemo can be administered as a shot in the muscle of the hip, thigh, arm, or even under your skin in a fatty part of the leg, belly, or arm.
  • Intravenous (IV)- it can be administered directly into some vein.
  • Intrathecal- injected into the space between layers of the tissue covering the spinal cord and the brain.
  • Intra-arterial (“IA)- injected directly into an artery leading to the cancer.
  • Intraperitoneal (IP) – chemo goes into the peritoneal directly.
  • Topical- this is chemo in form of a cream rubbed on the skin Indications.

Radiotherapy focuses on solid tumours including those of the spine, skin, cervix, and larynx prostate. It is often utilised in the case of breast cancer.

Chemotherapy, however, is utilised when dealing with cancers such as lymphoma, leukemia, and multiple myelomas. In addition, it can be used in the case of cancers of the lungs, breast, and ovaries.

When Given

chemotherapy treatment

Radiotherapy can be given at different events:

  • Radical Treatment (Curative)- given for prolonged benefits. Can be given alone or combined with other treatment.
  • Before a surgery to shrink some tumours or after surgery to suppress the development of any remaining cancer cells.
  • Before, during, or after Chemo/Hormone treatment- to enhance overall results.
  • Palliative Radiotherapy- given to shrink tumours as well as relieve cancer symptoms or even to prolong life too.

Chemotherapy, on the other hand, is given in the following events:

  • Neo-adjuvant therapy- given prior to a surgery to shrink a tumour.
  • Adjuvant Therapy- to minimise the chances of cancer returning by destroying cancer cells after surgery.
  • Peri-operative therapy- given prior to and after surgery.
  • Chemoradiation- chemo integrated with radiotherapy.
  • Palliative chemo- to help relieve cancer symptoms as well as slow cancer development after it has spread to other parts of the body.

Side Effects

Radiotherapy causes the following side effects:

Damaged non-cancerous cells may cause side effects. Fatigue is a popular side effect of radiotherapy. It is a feeling of exhaustion. This may occur little by little or at once. It varies between different people.

radiotherapy side effects

Other side effects include hair loss, and skin problems like sore skin, burning sensations, itching, peeling, or dryness. Such problems can go on for a number of weeks.

Chemo, on the other hand, affects different people differently. The chemo drugs taken are a major determinant. Common side effects include:

  • Skin problems
  • Headaches
  • Fatigue
  • Muscle pain
  • Loss of appetite
  • Abdominal pains
  • Nausea and vomiting
  • Constipation and diarrhoea
  • Other related problems

Though the approaches appear to be quite different, some of the side effects they cause are common, for instance, fatigue, hair loss, and skin problems.

However, there are certain products available which can help to relieve the side effects caused by cancer treatment including burn soothing gels to help reduce burning sensations caused by treatments that inflict burns.

For further information and advice on relieving post treatment ailments consult with your doctor who will be able to tell you the best course of action.


Both chemotherapy and radiotherapy are known to be effective in treating different types of cancer at varying stages, and which treatment is used will largely depend on each individual’s case and the type of cancer being treated.