USE OF RADIATION THERAPY IN TREATMENT OF HEAD NECK CANCER AND ITS SIDE-EFFECTS

With the advent of latest medical revolution and growth in medical technology, treatment of cancer has become feasible and life expectancy has seen a new horizon. Kind of cancer treatment always depends upon the size of tumour and severity of the patient. After analysing the overall health of the patient and stage of the cancer, treatment is opted. Apart from surgery and chemotherapy, Radiation therapy is also used by specialists these days.

What is Radiation therapy?

Radiation therapy uses high-energy x-rays or particles to destroy cancer cells or slow their rate of growth. It works by damaging the cancer cells and making it hard for them to reproduce. Your body is then naturally able to get rid of the damaged cancer cells. Radiation therapy also affects normal cells. However, your normal cells are able to repair themselves in a way that cancer cells can’t.Radiation therapy takes time to work. It takes days or weeks of treatment before cancer cells start to die. They will keep dying for weeks or months after treatment ends.

Radiation therapy can be used in many ways to treat oropharyngeal cancers. It can be used as the main treatment for small cancers.People with larger cancers may need both surgery and radiation therapy or a combination of radiation therapy and chemotherapy or a targeted drug.

After surgery, radiation therapy can be used, either alone or with chemotherapy, as an additional (adjuvant) treatment to try to kill any cancer cells that might not have been removed during surgery. This is called adjuvant radiation therapy. Most experts agree that radiation used this way should be started within 6 weeks of surgery.

Radiation therapy can also be used to help ease symptoms of advanced cancer, such as pain, bleeding, trouble swallowing, and problems caused by bone metastases (cancer that has spread to bones).

PROCEDURE

Before the of start radiation therapy, patient will have a treatment planning procedure called simulation. This is done to make sure that:

  • Your treatment area is mapped out.
  • You get the right dose of radiation.
  • The radiation dose to nearby tissue is as small as possible.

During the simulation, patients will have imaging scans and their skin will be marked with little tattoo dots. These marks help radiation cancer specialist and his team to make sure the patient is in correct position for the radiation treatments.

Positioning and Mask

Patient is made to lie on the back during simulation and treatments. To help they stay in the same position for each treatment, patient has to wear a mask that covers the face and upper body and attaches to the table. Patient will has to wear the mask during the simulation and each of treatments.

TYPES OF RADIATION THERAPY

    1. External beam radiation therapy

    The most common way to give radiation for these cancers is to carefully focus a beam of radiation from a machine outside the body. This is called external beam radiation therapy or EBRT. To reduce the risk of side effects, doctors carefully figure out the exact dose needed and aim the beam as accurately as they can to hit the tumour. The procedure itself is painless.

    Hyper fractionation: In this procedure the total radiation dose in a larger number of doses, for example giving 2 smaller doses per day instead of 1 large dose a day.

    Accelerated fractionation: In this procedure  2 or more doses each day are given so that the radiation treatment is completed faster (3 weeks instead of 6 weeks, for instance).

    Hyperfractionation and accelerated fractionation schedules may reduce the risk of cancer coming back in or near the place it started (called local recurrence) and might help some people live longer.

    Three-dimensional conformal radiation therapy (3D-CRT) and intensity modulated radiation therapy (IMRT) are two types of radiation therapy.

    Brachytherapy

    Another way to deliver radiation is by placing radioactive materials right into or near the cancer. This is called internal radiation, interstitial radiation, or brachytherapy. The radiation travels only a very short distance, which limits its effects on nearby normal tissues.

    Brachytherapy is not used often to treat oral cavity or oropharyngeal cancers because newer external radiation approaches, such as IMRT, are now very precise. When brachytherapy is used, its most often combined with external radiation to treat early lip or mouth cancers.

    Different types of brachytherapy:

    1. In one form, hollow catheters (thin tubes) are placed into or around the tumour during surgery. They’re left in place for several days while the patient stays in the hospital. Radioactive materials are put into the tubes for a short time each day.
    1. In another form, small radioactive pellets (about the size and shape of a grain of rice) are put right into the tumour. The pellets give off low levels of radioactivity for several weeks and, over time, lose their strength. The pellets themselves are just left in place and rarely cause any problems.

IMAGING TECHNIQUES USED

Patients will have to go through imaging scans while being in treatment position and wearing the mask. The scans will be used only to map the treatment area. They aren’t used for diagnosis or to find tumours.

  • X-ray scan
  • Computed tomography (CT) scan.
  • PET scan
  • Magnetic resonance imaging (MRI) scans.

Depending upon the findings of these scans, Radiation beams are then shaped and aimed at the tumour from several directions, which makes the treatments less likely to damage normal nearby tissues than older ways of giving external beam radiation.

SIDE EFFECTS OF RADIATION THERAPY

Radiation of the mouth and throat area can cause several short-term side effects, including:

  • Skin changes like a sunburn or suntan in the treated area that slowly fades away
  • Hoarseness
  • Loss of sense of taste
  • Redness and soreness or even pain in the mouth and throat
  • Sometimes open sores develop in the mouth and throat, making it hard to eat and drink during treatment.
  • Radiotherapy may also cause long-lasting or permanent side effects:
  • Damage to the salivary glands: Permanent damage to the salivary (spit) glands can cause a dry mouth. This can lead to problems eating and swallowing.
  • The lack of saliva can also lead to tooth decay (cavities). People treated with radiation to the mouth or neck need to practice careful oral hygiene to help prevent this problem. Fluoride treatments may also help.
  • Damage to the jaw bone: This problem, known as osteoradionecrosis of the jaw, can be a serious side effect of radiation treatment. This is more common after tooth infection, extraction, or trauma and it can be hard to treat. The main symptom is pain in the jaw. In some cases, the bone actually breaks. Sometimes the fractured bone heals by itself, but often the damaged bone will have to be repaired with surgery.
  • Damage to the pituitary or thyroid gland: If the pituitary or thyroid gland is exposed to radiation, their production of hormones may decrease over time. This can lead to problems with metabolism that may need to be corrected with medicine.

1. Why does radiation therapy cause side effects?

High doses of radiation therapy are used to destroy cancer cells. Side effects occur because radiation therapy can also damage healthy cells and tissues near the treatment area. Today, major advances in radiation technology have made it more precise, leading to fewer side effects.

For some people, radiation therapy causes few or no side effects. For others, the side effects are more severe. Reactions often start during the second or third week of treatment. They may last for several weeks after the final treatment.

2. Where it is used?

In treatment of early or advanced laryngeal or voice box cancers, in tonsillar and base of tongue cancers with or without chemotherapy. In oral or mouth cancers after surgery . in treatment of nasopharynx cancer  along with chemotherapy.

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