1. About cancer
A general term for abnormal cell growth and its uncontrolled spread. Cancer cells may grow into a lump called a malignant tumour. They may invade and damage surrounding tissue. Some may also break away from the original (primary) cancer and travel in the blood or lymphatic system to other parts of the body, where they form secondary tumours (metastases). The five main types of cancer are carcinomas, sarcomas, myelomas, lymphomas and leukaemia. Cancers at different sites in the body are discussed individually.
These cancer cells grow in an abnormal fashion, which means that the usual checks and controls that exist for the different cells in the body have been removed. As a result, cancer cells are able to continually replicate and so they increase in number.
Cells that grow abnormally are not neccessarily cancers. A benign tumour is a growth of cells in an abnormal fashion but is not a cancer. Another distinguishing feature of a cancer is its ability to spread, or metastasize. This means that cancer cells can learn to live in places in the body that are distant from where the cancer started.
Cancers appear at all ages but, typically, childhood ones are unlikely after age 18, and adult ones tend (with a few exceptions) to appear after age 40-60. About one person in three will develop a cancer in their life-time (not including skin cancers which two out of three will get).
There are over 200 different types of cancers known. One thing is common to all these different cancers though: they are all growing out of control.
Cancers usually take years to grow to a point where they threaten someone’s life. The growth rate is often thought to increase as the cancer enlarges but, as mentioned above, the rate of growth is usually constant. However this translates into a more rapid increase in size the bigger the tumour becomes. It may take as long as 10 years for a cancer to become apparent, but it may be only 1-2 years for a more rapid one to become visible.
2. Few words from statistics
Cancer is the second largest cause of death in Europe. Every year in Slovakia approximatelly 25 000 people die of cancer.
3. Ways of cancer treatment
Most used methods of the cancer treatment are:
- surgery, which is a removal of affected tissue by an operation;
- chemotherapy, which is using drugs or medicine;
There are a large number of different drugs that are used to treat cancer. Each type of cancer is only sensitive to particular drugs and there are many different types of drugs. In most cases a combination of drugs is given at the same time in order to maximise the efficiency of the treatment and in order to prevent the cancer cells from becoming resistant to the therapy. This is called combination chemotherapy. This combination of drugs (also known as a drug regimen) is tailored to each type of cancer so that side-effects are minimised, while benefits are maximised.
Chemotherapy may be given in tablet or capsules form, or by injection or infusion (slowly via a intravenous drip).
- radiotherapy.
4. Radiotherapy
Radiotherapy, also called radiation therapy, is the treatment of cancer and other diseases with ionizing radiation. This radiation deposits energy that injures or destroys cells in the area being treated by damaging their genetic material, making it impossible for these cells to continue to grow. Although radiation damages both cancer cells and normal cells, bu they are able to repair themselves and function properly. Radiotherapy may be used to treat localized solid tumors, such as cancers of the skin, tongue, larynx, brain or breast. It can also be used to treat leukemia and lymphoma (cancers of the blood-forming cells and lymphatic system). Radiation therapy may be used alone or in combination with chemotherapy or surgery.
In order to spare surrounding tissue the beam of radiation may also be rotated around the body, sparing the health tissue, while giving the maximum dose to the tumour. However, in order to achieve this level of accuracy, many X-rays films and Computed Tomography (CT) scans are taken to clearly identify where the tumour is. Once the precise location of the tumour is known, this information is then used to plan how the radiation can be delivered administered.
One type of radiation therapy commonly used involves photons, "packets" of energy. X-rays were the first form of photon radiation to be used to treat cancer. Depending on the amount of energy they possess, the rays can be used to destroy cancer cells on the surface or deeper in the body. The higher the energy of the x-ray beam, the deeper the x-rays can go into the target tissue.
Gamma rays are another form of photons used in radiotherapy. Gamma rays are produced spontaneously as certain elements, such as radium or uranium, release radiation as they decompose, or decay. Each element decays at a specific rate and gives off energy in the form of gamma rays and other particles. X-rays and gamma rays have the same effect on cancer cells.
4.1 External radiotherapy
External radiotherapy is given by focusing the radiation directly onto the tumour, using a radiotherapy machine. The process is painless and the principle is much like shining a light source or torch. By contrast, internal radiotherapy (also known as brachatherapy), is given either by implanting radioactive pellets or wires within or close to a tumour. Additionally, internal radiotherapy may be administered by giving a radioactive liquid by mouth or injection.
In external radiotherapy, a machine directs radiation onto the cancer and surrounding tissue. Different machines may be used: some are better for treating cancers near the skin, others are better for cancers deeper in the body depending on the amount of rays emitted.
4.2 Internal radiotherapy
Another technique for delivering radiation to cancer cells is to place radioactive implants directly in a tumor or body cavity. This is called internal radiotherapy. In this treatment, the radiation dose is concentrated in a small area, and the patient stays in the hospital for a few days. Internal radiotherapy is frequently used for cancers of the tongue, mouth, neck, etc.
Internal radiotherapy, is given either by implanting radioactive pellets or wires within or close to a tumour. Additionally, internal radiotherapy may be administered by giving a radioactive liquid by mouth or injection.
5. Side effects
Like all forms of cancer treatment, radiation therapy can have side effects. Possible side effects of treatment with radiation include temporary or permanent loss of hair in the area being treated, skin irritation, temporary change in skin color in the treated area, and tiredness. Other side effects are largely dependent on the area of the body that is treated.
Most people feel tired while they are having radiotherapy, particularly if they are having treatment over several weeks (even if they are not anaemic). The cause is not understood, but they should balance rest and exercise.
Radiotherapy sometimes affects the cells in the bone marrow which produce your blood cells. This is more likely if you are having a large area treated or if treatment is to the bones of the legs, chest, abdomen or pelvis. If this is likely in your case, you will have regular blood tests during your treatment to check the number of red blood cells in your blood.
If the level of red blood cells is low (anaemia), you may feel tired and need a blood transfusion or treatment with erythropoietin to boost your red blood cell count.
6. Radiotherapy machines for cancer treatment
The radiotherapy uses a much more intense form of radiation than X-rays. To put this into perspective, a radiotherapy machine will use 60-80,000 volts to produce the x-ray, a linear accelerator will use 6,000,000 - 20,000,000 volts. The machine then takes this voltage and converts it to X-rays or electrons, these are then refined and aimed so that only a single energy is used, focussed on a specific target point. The beam can be changed in size and shape but not intensity and so, to tailor the treatment for any one person, modifications are made to how it is positioned. The duration for which it is kept on, determines the total dose that is delivered. The dose of radiation is measured in Gray (abbreviated to Gy).
Linear accelerator ThoraScan™:
ThoraScan™ offers a revolutionary new way to digitally capture the thorax and uses the most efficient slot-scan technology ever designed. Its unsurpassed image quality is achieved by a 1 cm-thick, fan- shaped X-ray beam in combination with a multi-linear, scanning, solid-state X -ray detector. This unique image acquisition dramatically reduces scatter radiation, eliminating the need for a grid thus lowering patient dose. The new system has an effective exposure time of 20 ms, delivering unsurpassed image quality with all the associated workflow advantages of a direct digital system.
ThoraScan™ Digidelca-M:
The considerable increase of tuberculosis in the world is making it necessary to pay more attention to its prevention. A good method of identifying and reducing the impact of this disease is mass chest screening. Oldelft has been active in the field of tuberculosis screening since 1950. This latest screening system by Nucletron is a digital camera which has been developed from past systems such as the Electrodelca and Odelca. Benefits include a reduction in radiation from its predecessors and the cost-effectiveness of filmless screening.
7. A look into the future
Several new approaches to radiation therapy are being evaluated to determine their effectiveness in treating cancer. One such technique is intraoperative irradiation, in which a large dose of external radiation is directed at the tumor and surrounding tissue during surgery.
Another investigational approach is particle beam radiation therapy. This type of therapy differs from photon radiotherapy in that it involves the use of fast-moving subatomic particles to treat localized cancers. A very sophisticated machine is needed to produce and accelerate the particles required for this procedure. Some particles (neutrons, pions, and heavy ions) deposit more energy along the path they take through tissue than do x-rays or gamma rays, thus causing more damage to the cells they hit. This type of radiation is often referred to as high linear energy transfer (high LET) radiation.
Scientists also are looking for ways to increase the effectiveness of radiation therapy. Two types of investigational drugs are being studied for their effect on cells undergoing radiation. Radiosensitizers make the tumor cells more likely to be damaged, and radioprotectors protect normal tissues from the effects of radiation. Hyperthermia, the use of heat, is also being studied for its effectiveness in sensitizing tissue to radiation.
Other recent radiotherapy research has focused on the use of radiolabeled antibodies to deliver doses of radiation directly to the cancer site - radioimmunotherapy. Antibodies are highly specific proteins that are made by the body in response to the presence of antigens (substances recognized as foreign by the immune system). Some tumor cells contain specific antigens that trigger the production of tumor-specific antibodies. Large quantities of these antibodies can be made in the laboratory and attached to radioactive substances (a process known as radiolabeling). Once injected into the body, the antibodies actively seek out the cancer cells, which are destroyed by the cell-killing (cytotoxic) action of the radiation. This approach can minimize the risk of radiation damage to healthy cells. The success of this technique will depend upon both the identification of appropriate radioactive substances and determination of the safe and effective dose of radiation that can be delivered in this way.
8. Conclusion
We can cure many types of cancer today. The chance for absolut recovery is depending on the stage of the disease. If the stage of cancer is developed, the treatment is quite long and not effective enough. The cancer in high developed stage is the reason of such high mortality from it.
