Understanding Cancer Treatment Options: Chemotherapy vs. Radiation Therapy

by Ing Wei Khor

Chemotherapy and radiation therapy are two of the most commonly used cancer therapies. What are the differences between them, and when is each therapy applied? Answering these questions will help us understand the important role that these therapies play in treating cancer.

So, What Exactly Is Chemotherapy and Radiation Therapy?

Cancer chemotherapy encompasses all drugs used to treat cancer. In chemotherapy, drugs are injected or infused into the patient and spread throughout the body (systemic therapy). This means that chemotherapy is able to kill cancer cells that have metastasized to other organs away from the original tumor.

Radiation therapy involves the application of high doses of radiation to kill cancer cells or prevent tumors from growing. In contrast to chemotherapy, most types of radiation therapy are targeted to a specific part of the body to kill cancer cells (local therapy). Two main types of radiation therapy used to treat cancer are external beam radiation therapy and internal radiation therapy. In external beam radiation therapy, a machine administers radiation to a specific part of the body. Internal radiation therapy involves placing a radiation source inside the body where it emits radiation for some time. If the source is liquid, the radiation therapy then acts as a systemic therapy going throughout the body and killing cancer cells.

Chemotherapy vs. Radiation Therapy: What They Aim To Accomplish

Chemotherapy may be administered to cure (or eliminate) cancer, control its growth. It can also be used to manage symptoms and make the patient more comfortable (known as palliative care).

Similar to chemotherapy, radiation therapy can be used to cure cancer, control its growth, or act as palliative therapy. External beam radiation is often used for palliative care to shrink tumors and relieve the symptoms caused by the tumors including pain, breathing problems and loss of bladder control. Radiopharmaceuticals are also useful for treating cancer pain.

Chemotherapy and radiation therapy are typically not used to cure cancer. Instead, controlling cancer is a more realistic goal. Both treatments are used to shrink tumors before surgery to help improve the chances of success. Chemotherapy can also be given before radiation therapy, and vice versa, for the same reason. Chemotherapy and radiation therapy are often used after surgery to remove any cancer cells remaining after the surgery.

Dosing and Treatment Schedule

In chemotherapy, optimizing the dose and treatment schedule (or cycle) is a very important step in ensuring that the treatment is effective and does not cause overly harmful side effects. The dose of the chemotherapy drug is calculated based on a patient’s weight in kilograms or body surface area — a function of the height and weight. Chemotherapy is often given in cycles that include a dose of the drug (or drugs) on one or several days, followed by several days or even weeks without any drug. The reason for this type of cycle is to allow normal, non-cancer cells to recover from treatment side effects during the rest periods. The optimal dose and cycle varies with the drug and the stage of cancer. Often, different doses and treatment cycles of a particular drug are tested in clinical trials.

Unlike chemotherapy, radiation therapy has a lifetime cap. This means that there is a maximum amount of radiation that a specific part of the body can safely receive during the patient’s lifetime. If the lifetime maximum has been reached for one part of the body, another area that is far enough away from it can still be treated.

Efficacy of Chemotherapy vs. Radiation Therapy

The efficacy of both chemotherapy and radiation therapy is variable and depends on the type and stage of cancer. Other factors may include the patient’s age, other conditions and response to past cancer therapies.

Side Effects

Both therapies cause side effects because some normal cells are exposed to the treatment along with the cancer cells. Since radiation therapy is often local (administered to only one area of the body), it may have fewer side effects than chemotherapy which is systemic (goes throughout the body). However, the side effects will also vary depending on the radiation source and patient factors.

Cost Comparison

A 2021 global study found that ­­chemotherapy cost approximately $125 to $150 per hour. Considering that a chemotherapy cycle may involve several doses per week (each infusion ranges from minutes to hours), the duration of each cycle is from 2 to 6 weeks and that treatment often requires several cycles, the cost of a chemotherapy course may easily run into the thousands of dollars or tens of thousands of dollars. Radiation therapy varies in cost but tends to be more expensive than chemotherapy. It averages in the high thousands of dollars to tens of thousands of dollars for a course of therapy.

Both chemotherapy and radiation therapy are at least partially covered by many insurance plans. The American Cancer Society has a list of resources to help patients understand insurance coverage of treatment costs

We’re Here to Help

For 70 years,  Yosemite Pathology and Precision Pathology has advanced anatomic pathology in the Western United States. Today, our practice encompasses more than 20 board-certified anatomic pathology specialists. We offer a broad range of specialties including breast, gynecologic, hematology, thyroid, urologic and other pathologies. For more information about our treatment options and services, contact us today

Ing Wei Khor is a trained scientist and medical writer who is passionate about communicating science and medicine clearly and simply to a wide audience.


National Cancer Institute – How Is Chemotherapy Used to Treat Cancer?

National Cancer Institute – Radiation Therapy to Treat Cancer

National Cancer Institute – External Beam Radiation Therapy for Cancer

American Cancer Society – Getting Internal Radiation Therapy (Brachytherapy)

European Journal of Health Economics The cost of chemotherapy administration: a systematic review and meta-analysis

Cancer.Net – What to Expect When Having Chemotherapy