What’s The Difference Between Chemotherapy and Radiation?

Posted on December 9, 2022 in Radiation Therapy

Written by Dr. McCall

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Both chemotherapy and radiation therapy are used to treat cancer, a disease in which abnormal cells divide uncontrollably and can spread to surrounding tissue or elsewhere in the body.

  • Chemotherapy works by injecting powerful drugs in the body that kill fast-growing cells.
  • Radiation therapy uses x-rays or forms of radiation to slow or kill cancer cells.

These two cancer treatments can be prescribed individually, concurrently, or with surgery.

To help you weigh these two popular treatment options, the oncologists at SERO unpack the differences between chemo vs radiation and address common questions patients typically have.

By knowing the difference between chemo vs radiation, you will have a more active role in guiding your cancer care experience and will be more informed about why you are undergoing each treatment and what you can expect from cancer treatment.

Is Chemotherapy the Same as Radiation Therapy?

No, chemotherapy is not the same as radiation therapy.

Chemotherapy targets cancer cells throughout the body usually by using cytotoxic medications given intravenously. Radiation therapy uses high-energy beams (like x-rays or proton therapy) to target and kill cancer cells at a specific tumor site.

Further in this blog, you’ll see there are other differences between these treatments in how they kill cancer cells, how they are administered, and what side effects they cause.

Chemo vs. Radiation: What’s the Difference?

Both chemotherapy and radiation therapy are used to kill cancer cells, as well as to shrink or slow progression to other areas of the body. The techniques used in chemo vs radiation are different, however.

How Chemotherapy Works

Chemotherapy (or chemo) refers to cytotoxic anti-neoplastic drugs that are given intravenously or orally.

These drugs travel systemically (throughout the body) – this whole-body treatment is different than radiation, which is localized to one area.

Chemo is designed to disrupt cells that are rapidly dividing often by targeting specific points in the replication and division cycle of cells.

Unfortunately, healthy cells that also divide rapidly, like hair follicles and digestive tract cells, may also be damaged by certain chemo therapies. This damage to healthy cells is what accounts for some of the side effects patients experience when undergoing treatment.

How Radiation Therapy Works

Radiation therapy, also known as radiotherapy, refers to a type of cancer treatment in which ionizing radiation is delivered to cancerous tumors in the body. Several types of radiation treatment are used to treat cancer, including external beam radiation stereotactic radiosurgery, and brachytherapy.

Radiation acts primarily by disrupting the DNA of cancer cells, either directly or indirectly, which results in impaired cellular division and cell death.

Radiotherapy uses creative technology to isolate areas with cancer to limit the damage done to adjacent cells. The treatment itself takes seconds to minutes and is usually painless.

Treatment-related side effects vary greatly, but unlike chemo, the effects are typically limited to the area of the body being treated.

Chemo vs Radiation: Side Effects

Both chemotherapy and radiation therapy can damage normal cells in the process of trying to kill cancer cells. The type of side effects varies greatly depending on which modality is used.

The biggest difference between the resulting side effects of these treatments is that the side effects of radiation will be dependent on the area of the body that is exposed to the radiation.

Chemotherapy, since it’s given intravenously, can affect the entire body.

Common Side Effects of Chemotherapy

  • Fatigue: Chemotherapy can drain the body of its energy, making people feel tired despite large amounts of sleep
  • Hair Loss: Some, but not all, chemotherapy affects hair cells causing hair loss.
  • Decreased blood counts: Sometimes chemotherapy can affect the blood counts including red cells, white cells, and platelets. Low red blood cells contribute to fatigue, low platelet counts lead to easy bruising and bleeding, and low white blood cells may make people susceptible to infection. Blood counts are often monitored frequently with certain types of chemotherapy.
  • Nausea: Nausea and vomiting are common with chemotherapy and vary in severity though often respond to medications.
  • Other complications: The possible development of secondary cancers

Common Side Effects of Radiation Therapy

  • Skin conditions: Dry, inflamed skin at the radiation site or the development of breakdown or blistering.
  • Fatigue and stiffness: Can be seen in many patients undergoing radiation, usually toward the latter part of treatment.
  • Swelling (lymphedema): This is usually more associated with the presence of a tumor or recent surgery. Delayed development of swelling from radiation alone is less common, with modern treatment regimens and techniques.
  • Other complications: The possible development of secondary cancers

Side Effects of Combined Chemotherapy and Radiation

Every cancer is different depending on the cell type, location, and genetic mutations that led to the cancer’s development.

Often, treatment may require a multi-faceted approach. Attacking the cancer with multiple modalities including radiation, chemotherapy, and surgery may provide an improved chance of cure or an improved outcome.

Combined therapy can either increase or decrease the risk of side effects, depending upon the type of tumor, location, and regimens used.

Common side effects with combined modality treatment can also include fatigue, digestive issues, skin reaction, hair loss, pain, and fatigue.

Does Radiation Make You Sick Like Chemo?

Hair loss and nausea, and vomiting, commonly seen with systemic chemotherapy, are not generally a side effect experience with radiation.

These side effects can however be seen if a large portion of the abdomen or the scalp is included in the radiation fields.

Radiation side effects depend upon the site being treated, the size of the area receiving radiation, the total dose as well as the presence of prior treatment.

Radiation vs Chemo: Which is Better?

Neither radiation vs chemo is “better nor worse.”

Various treatment options are available for patients diagnosed with cancer, depending upon the type of cancer, stage, and the patient’s overall health at the time of diagnosis.

It comes down to which treatment type is more appropriate and preferable to the patient, depending upon the medical history, cancer type, and stage.

Ideally, anyone given a diagnosis of cancer should meet with a multidisciplinary team of specialists including a surgical, medical, and radiation oncologist who can present the latest and most effective treatment options for them to consider.