Written by : Dr.Kishore Kumar Das, MD
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.
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:
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.
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.
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