What is Radiation Therapy?
Radiation uses high doses of ionizing energy such as photons or protons to damage the DNA of cancer cells ultimately leading to cancer cell death. Radiation therapy (also called radiotherapy) damages both normal and cancer cells, but while normal cells repair themselves, cancer cells die or shrink after treatment.
Radiation therapy is usually reserved for high-risk or advanced cases of melanoma where surgery is not possible or may be complicated. It is rarely used to treat primary melanoma. Exceptions include patients who are not good candidates for surgery or those who refuse surgical treatment.
In patients with metastatic melanoma, radiation therapy is primarily used to palliate or lessen symptoms. Although radiation cannot cure advanced melanoma, it can frequently shrink tumors that cause discomfort. In the case of brain metastases, however, it can be a primary treatment, with the goal being relief of symptoms such as partial paralysis, headaches, and seizures or to prevent further tumor growth even in patients without symptoms.
Radiation Side Effects
Unlike chemotherapy—a systemic treatment that travels throughout the body via the bloodstream—radiation therapy is a localized treatment that is directed toward a specific site. Therefore, patients experience side effects related to the area of the body receiving radiation therapy. The type and severity of side effects vary from patient to patient.
Side effects from radiation are usually caused by irritation of normal tissue in the treatment area. While cancer cells are particularly sensitive to radiation and are irreparably damaged by it, normal tissue cells have the ability to repair themselves after being exposed to radiation. Therefore, most of the side effects caused by radiation therapy resolve in time after completion of treatment.
Be sure to alert your physician when side effects occur so that s/he may monitor you and provide the appropriate interventions to keep you as comfortable as possible.
TYPES OF RADIATION THERAPY BY STAGE
Primary tumors (Stage I-III)
Surgery is the standard treatment for a primary melanoma tumor. Rarely, radiation can be used to treat a primary melanoma in patients who are unable to undergo surgery or for whom complete resection is not possible.
Stage III Patients
Purpose: For those with multiple or large cancerous nodes, radiotherapy can be used after surgery to prevent the tumors from returning at that site, but radiation does not impact survival or the spread of tumors to other sites.
How it Works: Radiation damages both normal cells and cancer cells, but normal cells are better able to repair themselves. Radiation is given along with adjuvant therapy to help prevent cancer cells from growing back in that region.
Which Patients: Radiation may be given to Stage III patients who are at high risk for tumor recurrence in and around the lymph node region because they have multiple nodes with melanoma (≥3 nodes); large nodes (>3 cm); or lymph nodes with extracapsular extension. It is also used for Stage III patients who have tumors that are hard to remove because of their location. These include thick tumors or those on the head and neck where the surgeon is unable to get an adequate margin around the tumor.
How It’s Given:
- Patients receive treatment in a hospital or at an outpatient treatment center.
- In most cases, a linear accelerator—a high-energy x-ray machine—directs radiation to the affected area.
- A total dose of external beam radiation therapy is fractionated, or divided into several smaller doses (fractions), over a period of days (conventional fractionation).
- Treatment lasts a few minutes at a time, usually for five days a week over the course of two weeks.
- Hypofractionation is a type of radiation treatment that is being explored to understand the effectiveness of giving higher doses of radiation in fewer treatments, and the delivery of more than one dose of radiation within the same day.
Effectiveness: Radiation therapy does improve the control of disease recurrence at the site of resected disease in patients with high-risk features. However, it has not been shown to reduce the risk of distant disease.
Side Effects: The side effects of radiation therapy vary by location on the body, but can include hearing loss, skin breakdown, bone exposure, ear pain, hair loss, and lymphedema.
Stage IV Patients
Purpose: Radiation therapy in Stage IV patients is primarily used to relieve symptoms by shrinking the tumors. Where there is a single tumor it is hoped that in combination with newer medical treatments, radiation may prolong survival.
How it Works: Radiation damages both normal cells and cancer cells, but normal cells are better able to repair themselves. Radiation is given to help shrink the tumors with the goal of relieving symptoms.
Which Patients: Radiation may be given to Stage IV patients whose melanoma has spread to the bones or to parts of the body that make it difficult to remove the tumor surgically. Radiation may also be given when there is a single tumor.
How It’s Given:
- Patients receive treatment in a hospital or at an outpatient treatment center.
- In most cases, a linear accelerator—a high-energy x-ray machine—directs radiation to the affected area.
- A total dose of external beam radiation therapy is fractionated, or divided into several smaller doses (fractions), over a period of days (conventional fractionation).
- Treatment lasts a few minutes at a time, usually for five days a week over the course of two weeks.
- Hypofractionation is a type of radiation treatment that is being explored to understand the effectiveness of giving higher doses of radiation in fewer treatments, and the delivery of more than one dose of radiation within the same day.
Effectiveness: Radiation therapy is used with the goal of relieving symptoms, which is called palliative therapy. The radiation therapy is not expected to cure the cancer, but it may help shrink it for a period of time.
Side Effects: The side effects of radiation therapy vary by location on the body, but can include hearing loss, skin breakdown, bone exposure, ear pain, hair loss, and lymphedema.
Stage IV Patients with Brain Metastases
Purpose: Radiation therapy in Stage IV patients with brain metastases is primarily used to control the growth of or shrink melanoma tumors in the brain, in a precise manner.
How it Works: SRS (stereotactic radiosurgery) uses several powerful beams of radiation located at different angles around the head which come together to focus precisely on the tumor. Gamma Knife is one of the most advanced forms of SRS. The “knife” is formed by many intersecting beams of gamma radiation that deliver a concentrated dose to a precise area of the brain. This noninvasive procedure is the preferred treatment for metastatic brain tumors that were previously considered inoperable or at a very high risk for standard brain surgery.
Which Patients: Radiation may be given to Stage IV patients with brain metastases.
How It’s Given:
- Prior to the operation, imaging techniques including CT scans and MRIs are used to pinpoint tumor location.
- One treatment session is often all that is required. Gamma knife radiosurgery is available at many major medical centers.
Effectiveness: SRS is most effective when there are only a few small metastases. Typically, patients who have too many brain metastases to be suitable for SRS may be treated with whole-brain radiation (WBXRT).
Side Effects: SRS has fewer side effects than more diffuse radiation but still can cause hair loss, hearing loss, memory problems, and speech problems, depending on the location of the brain tumor.