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What is the Difference Between Chemo and Radiation?

Chemotherapy vs. Radiation

Receiving a cancer diagnosis can be overwhelming and it is normal to have questions.

When receiving your treatment plan, you will likely hear about chemotherapy and radiation treatments, or even a combination of the two. Learning about the difference between the two can help you better understand your diagnosis and treatment.

The Differences between Chemotherapy and Radiation Therapy

What Is Chemotherapy?

Chemotherapy, also commonly known as chemo, treats cancer by using drugs.

Chemotherapy is a “systemic” treatment, meaning it will work throughout the entire body to prevent the cancer from spreading further.

A medical oncology health professional, most likely a nurse or physician, will administer the chemotherapy. There are a variety of ways that chemo can be delivered — as an outpatient procedure, at a hospital, at a physician office, or even at home.

Administering chemotherapy can happen as:

  • An injection into a muscle, vein, or artery
  • Orally(by mouth)
  • An injection into the body (such as the abdomen)
  • Direct skin application

What Are the Side Effects of Chemotherapy?

Side effects of chemo will vary but can include:

  • Anemia and/or an increased risk of infection or bruising
  • Temporary hair loss
  • Loss of appetite, constipation, diarrhea, or nausea

What is Radiation Therapy?

Radiotherapy uses high-energy particles to damage or destroy cancer cells. Those particles or waves of radiation are sent in high doses to the cancer cells or tumour. Some normal cells will be affected by the radiation, but they are capable of repairing themselves, while cancer cells cannot.

Radiation can be used to directly treat the cancer or can be used to potentially improve the way you feel, minimising bone pain, for example. Radiotherapy can used on its own, but often it is combined with chemotherapy to best treat the cancer.

Types of radiotherapy

There are two ways to administer the radiation: internally or externally.

External Radiotherapy:

Known as beam radiation, this type of radiotherapy is delivered from a machine in a way that is very similar to receiving a chest x-ray. The average treatment is administered five days a week for one to 10 weeks. The duration depends on the overall health of the patient, the location of the tumour, and type of cancer.

When receiving treatment, you will be asked to lie flat on a treatment table placed under the radiation machine. Special shields or blocks will be used to protect other parts of your body, if needed.

Administering the radiation will only take a few minutes.

Types of external treatments

  • 3D conformal radiation therapy: using imaging, the tumour is mapped, which allows for beams of radiation to treat the cancer.
  • Stereotactic radiosurgery (SRS): using concentrated beams in high doses, oncologists can deliver treatment to hard-to-reach areas of the body, such as a head and neck, spine, or brain.
  • Intensity-Modulate Radiation Therapy: this process will give the oncologists the ability to find a “custom sculpt” of the shape of the tumour which can be more precise. With this information, the right amount of radiation can be more precisely delivered which helps to preserve the healthy tissue around the tumour.

Internal Radiotherapy:

Brachytherapy or internal radiation therapy is radiation placed inside the body. A source of radiation called an implant is placed on or near the tumour, which allows large doses of radiation to be delivered directly to the source of the cancer.

The implants, which can look like a wire, pellet, or seeds, may come with specific instructions such as limiting your time around children and pregnant women, or even avoiding them completely. The implant will stop giving off radiation in a few weeks to months and you can return to your normal activity. Once placed, the implant will permanently remain in your body.

The most common types of cancers treated with brachytherapy are:

  • Breast
  • Pelvic, ovarian, cervical
  • Head and neck
  • Lung
  • Perianal
  • Prostate

For more information, talk with your consultant and request an appointment to see a radiation oncologist at UPMC Kildare Hospital, UPMC Whitfield Hospital, UPMC Aut Even Hospital, or at Bon Secours Radiotherapy Cork in Partnership with UPMC Hillman Cancer Centre.