Late Side Effects of Radiotherapy

42 Abstract The study carried on 40 women with breast cancer treated by radiotherapy at Atomic medical center(Bagdad/Iraq) and Gülhane hospital (Ankara –Turkey) during 2007 . The data was collected by direct interview with the patients whose age range was (48-75) years . The research done after ( 2-11) years of treatment. Mild to severe type of mouth dryness was noticed in almost all the cases with variety of teeth and gum problems.80% of the patients developed diabetes mellitus, 30% of them were with no family history of disease.Edema of the arm (lymphoedema) in the same side of the affected breast occurred in 25% of the patients. Cardiac manifestations recorded in 15% including dyspnea due to congestion and pericardial effusion (diagnosed by Echocadiography) , cardiacmyopathy due to radiotherapy may cause such manifestations . Fibrosis of the lung causing shortness of breath on exertion and liability to chest infection and allergy diagnosed by chest tomography in 10% of the patients. 10% of the patients developed cataract in one eye (in the same side of the tumor).The ionizing radiation which is used in treatment of malignancy may cause cell damage in healthy tissues exposed to it because of its high energy capable to remove electron from the atoms in the biological molecules of the cells leading to their damage and appearance of some clinical problems in the treated patients.Modern sophisticated methods are designed such as radio-immunotherapy, conformal radiotherapy that match the case precisely, using radio-sensitizer drugs and accurate dosing in order to reduce the unwanted clinical effects of radiotherapy and the doctors have to balance the likelihood of cure with the risk of side effects.


INTRODUCTION
Radiotherapy is the use of a certain type of energy (called ionizing radiation) to kill cancer cells and shrink tumors. Radiation therapy injures or destroys cells in the area being treated (the target tissue) by damaging their genetic martial, making it impossible for these cells to continue to grow and divide. Although radiation damages both cancer cells and normal cells, most normal cells can recover from the effects of radiation and function properly. The goal of radiaton therapy is to damage as many cancer cells as possible while limiting harm to nearby healthy tissues [1]. Radiation is energy that moves through space or matter at a very high speed. This energy can be in the form of particles, such as alpha or beta particles, which are emitted from radiation materials, or waves such as light, heat, radio-waves, microwaves, x-ray and gamma rays.
Radioactive materials, also known as radionuclide or radioisotopes, are atoms that are unstable in nature, there is a tendency for unstable atoms to change into a stable form, as they form, they release radiation [2].Ionizing radiation is the energetic particles or waves that have the potential to ionize an atom or molecule through atomic interactions. It is a function of the energy of the individual particles or waves present, and not a function of the number of particles or waves present .A large flood of particles or waves will not cause ionization if the individual particles or waves are not energetic enough. This ionization if enough can be destructive to biological organisms, and can cause DNA damage in individual cells. Ionizing radiation are energetic Beta particles, alpha particles which are emitted from radioactive materials or waves (photons) e.g., x-ray and gamma ray. [3].
About half of all cancer patients receive some type of radiotherapy; R.T may be used alone or in combination with other cancer treatment, such as surgery and or chemotherapy. R.T may be used to treat almost every type of solid tumors including the brain, breast, cervix, larynx, lung, pancreas, prostate, skin, spine, stomach, uterus or soft tissue sarcoma. Radiation can also be used to treat leukemia and lymphoma.
Radiation dose to each site depends on a number of factors, including the type of cancer and whether there are tissues and organs nearby that may be damaged by radiation. For some types of cancer, radiation may be given to areas that do not have evidence of cancer this is done to prevent cancer cells from growing in the area receiving the radiation. This technique is called prophylactic radiation therapy. Radiation therapy also can be given to reduce symptoms such as pain from cancer that has spread to the bones or other parts of the body. This is called palliative radiation therapy [1].
R.T may be the only treatment used to cure the cancer; this is known as radical R.T. It may be used to reduce the size of the tumor before surgery, this is called neo adjuvant treatment and it is used after surgery also to make sure that all the cancer cells are destroyed. There are two types of R.T: -1-External R.T is where a machine is used to give a dose of energy, such as X -rays to attack the cancer cells.
2-Internal R.T is where the source of radioactivity is put inside the body so it can get closer to the cancer. This can be done in two ways: -A-Brachytherapy: -This is when a solid source of radioactivity is put next to a tumor to give a high dose of R.T. This means the effect on body tissue around the cancer is as little as possible.
Brachytherapy can be used to treat the cancers of the cervix, head and neck, uterus, prostatic gland, and skin. A minor operation is needed to put the source of R.T and the patient needs to stay in the hospital for a few days while it is in the place .When the treatment is over the radioactive source will be removed and the patient will be able to go home .
B-Radioisotope therapy: this is when a radioactive liquid (usually radioactive iodine) is given either as an injection in to a vein or as liquid to be drunk. Radioisotopes treatment can be used for thyroid, adrenal and bone cancers.

PATIENTS AND METHODS
The study carried on 40 patients with breast cancer who were treated by R.T, after undergoing radical surgery (Radical Mastectomy).The data was collected by direct interview with the patients.
2) Mild to severe type of mouth dryness was noticed in almost all the cases with variety of teeth and gum problems.   Cataracts may also occur due to aging processes but mainly in older persons. [13,14,2] Kirkuk University Journal /Scientific Studies (KUJSS) When we balance the benefit of the R.T with the mentioned unwanted clinical effects our opinion will be as follow: the cure from cancer is the most important aim of the doctors and researchers, so they are working hard to do that in one hand and trying to minimize the unwanted side effects of any procedure used for that in the other.
There are many measurements used nowadays to improve the technique of R.T and reduce its risks and side effects or introduce other treatment technique for cancers such as immunotherapy.
Radio sensitizers and radio protectors are chemicals that modify a cells response to radiation.
Radio sensitizers are drugs that make cancer cells more sensitive to effects of the radiotherapy.
Several compounds are under study as radio sensitizers. In addition anti cancer drugs, such as 5flurouracil and cisplatin, make cancer cells more sensitive to radiotherapy. Radio protectors (also called radio protectant are drugs that protect normal (non cancerous) cells from the damage caused by radiation therapy. These agents promote the repair of normal cells that are exposed to radiation.

Amifostine (trade name Ethyol R) is the only drug approved by the U.S Food and Drug
Administration (PDA.) as radio protectors, it helps to reduce the dry mouth that can occur if parotid glands(which to produce saliva and located near the ear). Additional studies are under way to determine whether amifastine is effective when used with radio therapy to treat other types of cancer. Other compounds are under study as radio protectors. Researchers are also studying the use of radio labeled antibodies to deliver doses of radiation directly to the cancer site (radio immunotherapy) . Hyperthermia, the use of heat, is also being studied for its effectiveness in sensitizing diseased tissue to radiotherapy. [1,10] Doctors are trying to improve cancer treatment all the time. They are now trying to shape radiotherapy beams to fit the cancer more precisely this is called (conformal radiotherapy or intensity modulated radiotherapy). Conformal R. T is used for several different types of cancer. It means that less normal tissues will be in R.T treatment area so the risk is lower.
A number of refinements and techniques are in use or under study to improve the effectiveness of external radiation therapy. Three -dimensional (3-D) conformal radiation therapy. Traditionally, the planning of radiation treatment has been done in tow dimensions (with and height). Three-dimensional (3-DO conformal radiation therapy uses computer technology to allow doctors to more precisely target a tumor with radiation beams (using width, height, and depth). Three-dimensional (3-D) conformal radiation therapy uses computer technology to allow doctors to more precisely target a tumor with radiation beams (using width, height and depth). [1, 2, 10].

CONCLUSION
1. Radiotherapy which is used in treatment of cancer may cause damage to the healthy tissues also because of its high energy, precipitating many unwanted late clinical effects.
2.The clinical manifestations recorded during the study were , dryness of the mouth (the result of effect of R.T on the tissues of salivary glands ) , lymph edema of the arm , dyspnea due to cardiomyopathy and pericardial effusion , shortness of breath on exertion because of lung fibrosis , hyperglycemia ( effect of R.T on pancreatic tissues ) and cataract.
3.There are many measurements used recently in the centers of cancer treatment to reduce the risks of radio therapy .