Superficial X-Ray Therapy for Skin Cancers
Radiation therapy (or radiotherapy) is the treatment of cancer using radiation. During radiation treatment, radiation is directed to the target tissue and transmits energy that damages and destroys the cancer cells. It does this by damaging the genetic material of the cells which triggers cell death. The radiation damages genetic material in both normal and malignant cells and does not discriminate between them. However, normal cells are able to recover from the damage, whilst the cancer cells do not. Radiation therapy aims to maximize the number of cancer cells destroyed, while minimizing the damage to nearby normal cells.
The main type of radiation used for the treatment of skin cancers are x-rays. X-rays can be generated with different energy levels. High energy x-rays are able to penetrate deep into the body, and are used to treat internal cancers. In contrast, low energy x-rays do not penetrate very deep into the body and transmit most of their energy into the skin and are therefore used for the treatment of skin cancers. These low energy x-rays are often called superficial or orthovoltage x-rays. In addition, electron beams and gamma rays are other forms of radiation that are sometimes used to treat skin cancers.
Radiation therapy is not suitable for all types of skin cancers. Some of the factors affecting whether radiation therapy can be used include:
- Type of cancer
- Site of the cancer
- Previous use of radiation therapy
- Suitability of other treatments
- Patient preference
- Type of cancer
Different cancers vary in their sensitivities to radiation induced damage, which influences how successful the radiation therapy will be. For example, melanomas are less sensitive to radiation, and are rarely treated with radiation therapy. Skin cancers which are relatively sensitive to radiation and commonly treated with radiation therapy include:
- Basal cell carcinoma
- Squamous cell carcinoma
- Cutaneous lymphomas
- Kaposi sarcoma
- Merkel cell carcinoma
- Site of the cancer
Radiation therapy is often used in sites in which surgery may be difficult, such as the eyelids. Some areas of the body are more likely to develop side effects from radiation therapy, such as the lower legs, and in these areas other treatments may be preferred.
If a site has previously been treated with radiation, then further radiation therapy cannot be used. If a skin recurs after radiation treatment then other treatments, such as surgical excision are usually preferred.
In addition to the factors above, there are a number of other factors that determine the suitability of radiation therapy. Your dermatologist will be able to advise you whether your skin cancer is suitable for radiation therapy.
