Side Effects of Radiotherapy


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The aim of radiotherapy, both external radiotherapy and brachytherapy is to destroy the DNA of the cancer cells and prevent them from growing.

Unfortunately, during the process, normal, healthy cells which lie in the path of radiation are also affected by the high energy, ionising radiation rays. These damaged cells cause side effects, both immediately after the radiation process as well as delayed reactions.

The type and seriousness of these side effects will vary from person to person based on the age of the person and his/her general health. The side effects will also be different depending on the site and type of the cancer being targetted as well as the dosage and duration of radiotherapy.

Diffferent types of cells react differently to the ionising rays. Rapidly dividing and fast growing cells are affected the most - these include skin cells, cells lining the mouth and gastrointestinal (GI) tract and blood cells in the bone marrow. The cells of the hair follicles are also affected, leading to the most common side effect of hair loss.

Radiotherapy for breast cancer may affect the skin and the underlying tissues, including the bones of the ribcage and the muscles the heart and the lungs. It may also affect the tissues of the neck and the thyroid gland.

Brachytherapy causes less side effects than external beam radiotherapy since the radiation is usually located and isolated in a small area.

Side Effects of  Radiotherapy

There are two types of side effects - Early side effects and late side effects

Early Side Effects:

Early side effects may start immediately after the radiation treatment process is over or within a few days. They, however, improve over time - usually within weeks. They are:

  • Extreme Fatigue - Extreme fatigue which does not get better even on rest is one of the commonest immediate side effect. It usually occurs after a day or two of the start of the radiation process and gets worse as the treatment proceeds. Fatigue is worse when larger areas of the body are irradiated and may be considerably decreased in radiotherapy for breast cancer, espcially internal radiotherapy or brachytherapy.

  • Flu-like syptoms - Some people may be feverish with flu-like symptoms for a few days after radiotherapy.

  • Nausea and vomiting - Nausea and Vomiting is a common effect of external beam radiation. This is more common if radiation rays are targetted at the stomach or abdomen, although it may occur in radiotherapy for any type of cancer anywhere in the body. This is called Radiation sickness and it usually goes away a few weeks after the radiation therapy is finished.

  • Lack of appetite - Lack of appetite can be due to stress over the treatment. But more commonly, it is a result of side effects like sore mouth, dry mouth, problems swallowing and nausea and vomiting. The loss of appetite starts within a few days of starting the treatment. Inflammation of the esophagus (esophagitis) with sensations of difficulty in swallowing may contribute to lack of appetite.

  • Skin changes - Skin changes may occur over the radiated area. The skin may be red, dry, tender or itchy. It may appear bruised and irritated. It can peel with formation of small ulcers and sores. This can cause the skin to become wet, sore, or infected, especially under the breasts and in the folds of the skin.

    Most skin changes occur in the first 2 weeks of starting treatment and fade away within months of the end of the treatment. In some cases however, the skin changes may be permanent , leadng to discoloration and hardening of the skin.

    The skin is affected more in external radiotherpy than in internal radiotherapy.

    Radiation burn after Radiotherapy
    Skin Burn after Radiotherapy

  • Decreased Blood Cells - Destruction of red blood cells can lead to anemia. The decrease in oxygen saturation of the cells due to anemia can also cause fatigue. Destruction of white blood cells can lower the person's immune response to pathogens and leave him/her at risk for developing infections.

  • Loss of Hair - Hair loss begins about 2 to 3 weeks after radiation therapy starts. The hair regrows after about 3-6 months. The amount of hair loss depends on the amount of radiation received and the duration of treatment. When the hair regrows, the texture of the hair may be different and the growth may be sparse or patchy - this is because some of the hair cells (follicles) may not revive after the end of the treatment process.

    Hair Loss after Radiotherapy
    Hair Loss after Radiotherapy

  • Mouth Problems - There may be dryness of the mouth with decreased saliva secretion or thick saliva. Dryness can lead to small sores or cuts within the mouth.

  • Radiation pneumonitis Radiation can cause inflammation of the lung tissues. The symptoms of radiation pneumonitis most commonly occur 2 to 3 months after completing radiation therapy and can include shortness of breath, chest pain (often sharp), cough, and fever.
Delayed Side Effects of Radiotherapy:

As survival rates of breast cancer treatment has improved, the incidences of delayed side effects of breast cancer has also increased.

Delayed side effects may first occur 6 or more months after radiation therapy is over. They are more common when high doses of radiation are necessary or when the affected person is older or suffers from general ill health. In these cases, the cells may not recover completely after the treatment - the damage becomes evident months or years after the treatment process is over.

  • Skin Changes - The skin may suffer loss of elasticity with darkening or hyperpigmentation of the skin. The skin can feel thick and corrugated. There may be changes in the sensitivity of the skin.

  • Secondary Carcimonas - Rarely, secondary cancers like soft tissue sarcomas (STS) may occur in some people. It has been known for a long time that radiation can increase the risks of secondary carcinomas. Radiation can also cause blood cancers like acute myelogenous leukemia (AML), chronic myelogenous leukemia (CML), and acute lymphocytic leukemia (ALL). Risks are higher in cases where higher radiation doses are given.

  • Radiation-Induced Hypothyroidism - Radiation over the head, neck and chest can cause scarring of the thyroid tissue with resulting hypothyroidism. This is more common in women who have had radiation followed or preceded by immunotherapy.

  • Heart Problems - Heart problems such as irregular heartbeat, congestive heart failure or coronary artery disease can occur due to damage to the heart muscle. The damage weakens the heat muscles and valves. Pericardial effusion ( fluid buildup) can occur around the heart.

  • Radiation Fibrosis Syndrome - Radiation can cause inflammation and scarring of the lung tissues. The tissues become less elastic and can cause problems with breathing.

  • Pulmonary Fibrosis - Pulmonary Fibrosis is a permanent scarring and damage to the lung tissues.

Although radiotherapy can cause side effects, it must be remembered that the benefits far outweigh the risks.

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