Side Effects of Radiation Therapy

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Radiation therapy reduces tumors by directing streams of high-energy particles at cancer cells. As the powerful rays pass through the patient’s skin, tissues and muscles before reaching their intended target, they can also damage healthy cells and cause skin changes, bladder irritation, fatigue and nausea.

Most side effects develop as tissue damage accumulates over several sessions of radiation therapy. A single cycle may last up to eight weeks, during which the patient may begin to notice side effects. As treatment progresses, side effects are often more severe.

Side effects of radiation therapy are most often temporary and limited to the treatment site. However, some may also be chronic, appearing months or years after the patient has finished treatment

Side Effects of Radiation to the Chest (Pleural Mesothelioma)

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  • Difficulty Swallowing
  • Shortness of Breath
  • Potential Scarring of the Lungs (Fibrosis)
  • Cough
  • Breast Tenderness (In Females)

Side Effects of Radiation to the Abdomen (Peritoneal Mesothelioma)

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  • Nausea/Vomiting
  • Diarrhea
  • Cough
  • Bladder Irritation

Advanced methods of delivering radiation therapy can help reduce the amount of surrounding tissue that is exposed to radiation, but some side effects may still occur in the area where the radiation entered the body. Side effects of radiation are typically more constrained than the side effects of chemotherapy, which can affect the entire body.

Factors that Affect a Patient's Likelihood of Developing Side Effects from Radiation Therapy

  • Patient's overall health
  • Additional treatments
  • Area of the body receiving radiation therapy
  • Daily dose of radiation administered
  • Total dose of radiation
  • Genetics

Skin Problems

Skin Symptoms

  • Darkening of the skin
  • Peeling
  • Redness, Tenderness or Irritation

Temporary skin irritation is the most common side effect of radiation therapy. Skin problems from radiation therapy closely resemble a sunburn. These complications can include rashes, redness, a tight feeling or swelling. Radiation-related irritation, known as radiodermatitis, is most common at the point where the radiation beam was focused. Pleural mesothelioma patients, for example, will notice the skin irritation in their chest area, while peritoneal mesothelioma patients will notice it in the skin on their abdomen.

To manage skin irritations from radiation therapy, adopt a skin care regimen designed to alleviate some of the pain and irritation. Keep the irritated area clean and moist. Excessive washing may lead to further dryness, so wash gently and only when necessary using lukewarm water and mild soap. Pat “ not scrub “ the area with a towel to dry it. Avoid scratching the area or applying traditional cosmetic lotions; use a mild unscented cream instead. Patients should avoid sun exposure or tanning beds during this portion of their treatment.

Quick tip! Wear loose-fitting clothing of light, breezy materials such as cotton to protect the irritated skin and reduce itching.

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Bladder Irritation

When radiation is directed at the abdomen, the bladder may be affected by the powerful rays, resulting in bladder irritation. Radiation therapy may make it difficult to completely empty your bladder, urinate at normal intervals or control the flow of urine from your bladder when you cough or sneeze. It may also cause cystitis, or an inflammation in the bladder. In rare cases, urine may appear bloody or the bladder may begin to cramp or spasm. These side effects may appear within three to five weeks of treatment.

Although bladder irritation typically resolves itself within two to eight weeks of the last radiation therapy session, doctors can prescribe antibiotics to reduce infection-related issues. Patients can also take several steps to reduce the irritation as it occurs. Consuming six to eight cups of water, broth or juice per day so that urine runs clear, as well as avoiding caffeinated beverages, alcohol, tobacco and spicy foods can help alleviate bladder pain, burning and spasms.


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Fatigue is also common during radiation therapy. It is typically most severe two to four hours after a radiation session. It may also peak between the third and fifth week of treatment as the healing process uses more and more of the patient's energy. Fatigue usually disappears several weeks after a patient completes their entire radiation therapy regimen.

Nausea and Vomiting

Nausea and vomiting are less common than other radiation therapy side effects. In a study of 22 malignant pleural mesothelioma patients who received palliative radiation therapy, only one patient experienced nausea and vomiting in the three month span after treatment. These side effects are most common in patients who receive radiation to the abdomen and sustain damage to their gastrointestinal tract, but they are also common in patients receiving other types of mesothelioma treatment, especially chemotherapy.

Anti-nausea medications are available for mesothelioma patients receiving radiation therapy. One of the most common anti-nausea drugs for cancer patients is ondansetron (Zofran).

Nutrition Recommendations to Manage Radiation-Induced Nausea

    Reduce Consumption

  • Large Meals
  • Fried, Greasy or Spicy Food
  • Foods with a Strong Smell
  • Increase Consumption

  • Small Meals and Snacks
  • Nutrient-dense Foods
  • Soft, Easily Digestible Foods such as Toast and Eggs
Learn more about nutrition needs for mesothelioma patients

Rare but Major Complications

Methods of radiation delivery that may reduce the potential for side effects include:

  • Smartbeam Image Modulated Radiation Therapy
  • Stereotactic Radiation Therapy
  • Proton Therapy

Radiation therapy can also cause severe complications, although these conditions are rare. Pleural mesothelioma patients are more at risk for these complications because their radiation is directed at the lung. Scar tissue may accumulate on the lung after repeated sessions, but this side effect is thought to be reversible. Radiation for pleural mesothelioma also has the potential to cause inflammation of the lungs and/or the lining of the heart as well as compression of the heart.

Radiation to the chest can also cause damage to the heart muscle, a condition known as cardiac toxicity. This condition can disrupt the natural rhythm of the heart or reduce the heart's ability to pump enough blood to the rest of the body. This condition can also be caused by certain chemotherapeutic drugs, including doxorubicin, which is commonly administered alongside radiation therapy in the treatment of mesothelioma.

These complications are less common in patients who receive highly specialized forms of radiation therapy. Some of the most sophisticated machines are able to specifically target the cancerous area and reduce the amount of surrounding tissue that is exposed to radiation.

A Study of Radiation Therapy's Effects on Mesothelioma Patients

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In 2000, the Memorial Sloan-Kettering Cancer Center conducted a study of post-surgical radiation therapy in 88 malignant pleural mesothelioma patients. Most patients experienced multiple symptoms. Fifty-five patients experienced skin irritation, 55 reported nausea and vomiting and 54 experienced fatigue. These side effects were ranked in severity on a scale of zero (most mild) to four (most severe). The majority of patients ranked their side effects as a zero or one, and only four patients experienced a side effect that they ranked as a four.

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  1. American Society of Clinical Oncology – Side Effects of Radiation Therapy. (2010 July 12). Retrieved from:
  2. Bissett, D. (1991). The role of palliative radiotherapy in malignant mesothelioma. Clinical Oncology, 3(6), 315-317. Retrieved from:
  3. Cleveland Clinic – Common Radiation Therapy Side Effects. (2009). Retrieved from:
  4. National Cancer Institute. (2010, June). Radiation Therapy and You: Support for People With Cancer (NIH No. 11-7157). Bethesda, MY.
  5. National Cancer Institute – Radiation Therapy for Cancer. (2011). Retrieved from:

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