Is My Radiation Treatment Working?

Posted on July 1, 2022 in Radiation Therapy

Written by Dr. Wild

Learn more about the author

If radiation therapy is part of your cancer treatment plan, you may wonder how quickly the radiation will kill cancer cells and when you will be able to “see” results. 

Though this eagerness is normal, it is important to remember that cancer is a silent disease. Rarely is it something you can visualize with the naked eye.

That being said, only tumor marker tests, blood tests, and imaging scans can determine if your radiation treatment is working. 

Your SERO provider will use these tools throughout your treatment to monitor your progress. If your cancer does not respond to radiation, they may introduce an additional therapy (adjuvant therapy) or a different treatment altogether (second-line treatment).

Keep reading to learn about how to determine if your radiation treatment is working.

What Is Radiation Therapy?

Radiation therapy, also called radiotherapy, is a type of cancer treatment that uses high doses of radiation to kill cancer cells. This treatment modality is localized, meaning it can be directed at a specific part of the body with extreme precision. Chemotherapy, for comparison, is considered a systemic treatment.

Signs Radiation Therapy Is Working

For most patients, the success of radiation therapy is determined in the weeks or months following the completion of the treatment. 

This is due to the fact that there is often a delay from the start of radiation to the time that the tumor shrinks or disappears. 

It can be difficult for patients to tell if their tumor is responding to radiation therapy. If the tumor is causing pain or bleeding, some patients will see rapid improvement. 

For other patients, there may be no physical changes to indicate a response. Fortunately, there are several medical tests your doctor can use to see if your tumor has responded to treatment. These tests include:

Tumor Marker Tests

Tumor marker tests can show different substances in your blood, urine, or body tissues. More specifically, these tests look for proteins, enzymes, and other chemicals released by tumors as they grow. A decrease in the level of a tumor marker may suggest that the cancer is responding to treatment. 

Imaging Tests

Imaging technology is often used to help radiation oncologists visualize cancer in the body. These tests can indicate if cancerous tumors have shrunk, grown, or stayed the same. They may also indicate if the cancer has spread to other areas. 

Most of the time, imaging tests are done after the radiation is complete. There are certain circumstances where your doctor may perform daily imaging tests and may be able to tell if the tumor is shrinking in the midst of treatment.

Common imaging tests include:

  • Bone scan
  • X-ray
  • CT scan
  • MRI
  • Ultrasound
  • Mammogram
  • PET scan

The frequency of tumor marker or imaging tests will depend on your cancer type and stage. It may also vary depending on what your cancer health insurance will and will not cover. Your oncology team will determine which tests to perform and the optimal frequency for your cancer. 

What If Radiation Does Not Work?

During radiation therapy, your radiation oncologist and nurse will monitor your progress. This progress will likely be slow, especially at first. It can take days or even weeks for cancer cells to die and for tumors to shrink. 

Though it is important to be patient, you should also be aware of symptoms that may indicate radiation therapy is not working. 

Contact your doctor if you experience any of the following:

  • A new or growing lump under your skin
  • Pain that gets worse
  • Broken bones—a sign that the cancer has spread to your bones 
  • Headaches, seizures, confusion, dizziness
  • Coughing or trouble breathing
  • Yellowing of the eyes
  • Stomach pain
  • Unexplained weight loss
  • Persistent fever 

If doctors determine that your cancer is not responding to your current course of treatment, they may adjust your radiation dose. 

They may also recommend adjuvant therapy—additional therapy that is given to maximize the effectiveness of the primary treatment. 

Or they may recommend a second-line treatment—a different treatment that is likely to be more effective.  Depending on your cancer type and stage, your oncologist may suggest:


Chemotherapy uses powerful drugs to target and destroy fast-growing cells in your body. A course of chemo typically takes three to six months. 

Targeted Therapy

This treatment option is a type of chemotherapy. However, the drugs are less toxic to healthy cells.   


Doctors may recommend surgery to remove a cancerous tumor. Sometimes, radiation therapy is used before surgery to make the lesion smaller. 


Immunotherapy boosts a patient’s own immune system, allowing it to find and attack cancer cells. 

Stem or Bone Marrow Transplant

Stem cell transplants help replace the bone marrow cells that have been destroyed by other cancer treatments like chemotherapy or radiotherapy.

Some cancers rely on hormones, or substances created by the body, to grow. Hormone therapy blocks or alters certain hormones to treat cancer.

Second Opinion for Cancer Treatment

If your cancer is not responding to your current treatment plan, you may consider consulting another physician. Though many individuals are reluctant to see a different doctor—fearing it could create an uncomfortable situation with their current oncologist—most medical professionals encourage patients to get a second opinion. Your oncologist may even have suggestions or referrals.

Why are second opinions so important?

First and foremost, they offer peace of mind. Another physician can confirm the prognosis determined by your original care team, quelling any “what ifs” you may have. 

On the contrary, another medical institution may have access to different treatment modalities, such as more advanced radiation technology or emerging clinical trials. This could be life-saving for some patients, especially those who have exhausted other treatment options.

Advanced & Effective Radiotherapy

At SERO, our radiation oncologists are dedicated to offering patients the most advanced, state-of-the-art radiotherapy techniques available. We serve patients who have recently been diagnosed as well as individuals who are seeking a second opinion. 

To learn more about your cancer treatment options, contact us to schedule an appointment at one of our 20 locations in the Charlotte Metro area.