Cancer Treatment: Radiation Therapy
Radiation therapy is one of the many tools used to combat cancers. Radiation treatments utilize high-energy waves such as x-rays to kill cancer cells. Radiation can be used alone or in conjunction with other treatments (e.g. chemotherapy and surgery) to cure or stabilize cancer.
Like other therapies, the choice to use radiation to treat a particular cancer depends on a wide range of factors. These include, but are not limited to, the type of cancer, the physical state of the patient, the stage of the cancer, and the location of the tumor.
Radiation can harm both cancerous and normal tissues, the treatment is based on the fact that fast growing cells, such as those found in tumors, are more sensitive to radiation damage. The radiotherapy technique used depends on the type, extent and location of the cancer, and the goal of treatment.
Internal radiation called brachytherapy is the process of implanting radioactive material onto or near the tumor or placing radioactive sources into the body. It can be temporary or permanent. Depending on the location of the implant the treatment may be handled as either an in- or out-patient procedure.
External radiation therapy utilizes a machine to deliver radiation to the tumor. This therapy is primarily an outpatient treatment. Most protocols last approximately 4-7 weeks with treatments given 5 days per week.
Both internal and external therapies act to destroy the ability of the cancer cells to reproduce. There are several different types of radiation that may be utilized:
Photon radiation: uses high energy rays composed of particles of energy called photons. Photon radiation acts by disrupting the molecules of the target cells, interfering with normal cell functions. There are several types of photon radiation:
- Gamma rays: are produced by the breakdown of radioactive isotopes of elements such as Cobalt-60 and radium
- X-rays: originate from machines that excite electrons using cathode ray tubes or linear accelerators.
Particle radiation: Uses subatomic particles, particles that make up an atom, to disrupt cells. There has been limited use of particle radiotherapy, such as proton therapy, in clinical practice due to the complex and costly equipment for its production, but there are some advantages for using this method. It can deliver higher dose of radiation to the target volumes with less damage to the surrounding tissue. This should allow for treatment with fewer margins, more effective treatments and reduced side effects.
Radiation Cancer Treatment
Aim for Radiation Cancer Treatment
The aim of radiation therapy is to cure cancer, where possible, whilst maintaining acceptable function and cosmesis. Radiation can be used alone or with chemotherapy or surgery.
Where cure is not possible, the aim is the relief of symptoms (palliation) of cancer, thereby improving the person's well-being. The treatment with radiation is held off until the patient needs it to alleviate pain after the tumor has spread. Radiation may be withheld until it will be most beneficial for the patient's comfort.
Indications for Radiation Therapy
Radiation therapy is the principal treatment for various skin cancers; cancers of the mouth, nasal cavity, pharynx and larynx; brain tumours and many gynaecological, lung cancers, and prostate cancers.
Radiation therapy plays a leading role in conjunction with surgery and/or chemotherapy in breast cancer, bowel cancer, bladder cancer, Hodgkin's disease, leukemia and lymphomas, thyroid cancer, childhood cancers, gynaecological and testis tumours, as well as many other cancers and certain benign conditions.
Action of Radiation Therapy
Radiation therapy works by destroying cells, either directly or by interfering with cell reproduction using high-energy X-rays, electron beams or radioactive isotopes. When a radiated cell attempts to divide and reproduce itself, it fails to do so and dies in the attempt.
Normal cells are able to repair the effects of radiation better than are malignant and other abnormal cells. Thus, normal cells are able to recover from exposure to radiation and maintain integrity and viability better than malignant cells.
If the dose and delivery of radiation are well chosen and the disease is localized to the region of treatment, the cancer dies, whereas the normal tissues survive and the patient is made well again.
If fewer than all the cancer cells are killed, improvement may only be short lived and the cancer may regrow. Since normal tissues are less able to withstand the effects of further radiation, repeated treatments at a later date are seldom beneficial.
Chemotherapy treatment uses medicine to weaken and destroy cancer cells in the body, including cells at the original cancer site and any cancer cells that may have spread to another part of the body. Chemotherapy, often shortened to just "chemo," is a systemic therapy, which means it affects the whole body by going through the bloodstream.
There are quite a few chemotherapy medicines. In many cases, a combination of two or more medicines will be used as chemotherapy treatment for breast cancer.
Chemotherapy is used to treat:
- early-stage invasive breast cancer to get rid of any cancer cells that may be left behind after surgery and to reduce the risk of the cancer coming back
- advanced-stage breast cancer to destroy or damage the cancer cells as much as possible
In some cases, chemotherapy is given before surgery to shrink the cancer.
In this section, you'll learn more about how chemotherapy works, chemotherapy medicines, and what to expect with chemotherapy. You also can learn about chemotherapy side effects and ways to manage them.
