Screening and early diagnosis of cancer Sometimes cancer can be detected before it causes symptoms. Screening for people who do not have any symptoms or who are at high risk is called cancer screening. Cancer screening includes physical examinations, laboratory tests, and direct or indirect internal examinations. Laboratory tests include blood and urine tests, cervical smears, and fecal occult blood tests. Visceral examinations can be performed through a very thin tube such as a colonoscope or gastroscope, allowing the doctor to examine the inside of the stomach and large intestine directly, or indirectly through X-ray images (e.g., mammograms for tumors in the breast). There are many factors that a doctor needs to consider before recommending a particular test. Examples include the person’s age, medical history, general health, family history, and lifestyle habits. In addition, the accuracy and risk level of the test must be considered. If cancer is found, doctors need to consider the effectiveness of treatment and side effects. Usually, the earlier a tumor is detected and treated, the more effective the treatment will be. Early manifestations of cancer: Having regular medical checkups and not waiting for problems to occur is a good way to detect tumors early. However, you should also know some symptoms related to cancer: change in urinary and bowel habits, wounds that do not heal for a long time, painless, harder lumps in the breast or other parts of the body, indigestion or difficulty in swallowing, obvious changes in warts or moles, or irritating cough or hoarseness. Having these symptoms is not necessarily a sign of cancer, they can also be caused by other common illnesses. It is important, however, that if you have any of these symptoms, do not wait until you feel pain before going to the doctor; early stage cancer is usually painless. Diagnosis of cancer: If you have some symptoms related to cancer, your doctor will ask you about your condition and do a physical examination. In addition, your doctor will usually perform tests and examinations, including imaging tests to look inside your body; endoscopic examinations that allow the doctor to look directly inside certain organs; and laboratory tests. In many cases, the doctor will need to remove diseased tissue and examine it under a microscope to see if there are any cancer cells. Imaging: Imaging of an area of the body can help the doctor determine if a tumor is present. x-ray is the most common way doctors use, such as chest x-ray and x-ray of bones. There are also special X-rays, such as CT scans: a computer connected to an X-ray machine that produces a series of detailed images of the inside of the body. Magnetic Resonance Imaging (MRI): A powerful electromagnet is connected to a computer to produce images similar to a CT scan but with different effects. Radionuclide scan: A patient is given a mildly radioactive substance orally or by injection, and a scanner measures the level of radiation in certain organs, which is then analyzed by a physician for abnormal areas of radioactive concentration in an organ. Ultrasound: Another method of examining the internal structures of the body. These high-frequency sound waves, which cannot be heard, enter the body and bounce back, creating an ultrasound image. These images can be displayed on a screen like a television or printed out on paper. Endoscopy: During an endoscopy, the doctor passes a very thin tube through the throat, trachea, esophagus, intestinal cavity, vagina or uterus for direct observation, while abnormal tissue or cells can be collected for pathological analysis. Laboratory tests: Laboratory tests such as blood and urine tests can provide important information to the doctor. If cancer is present in the body, the levels of certain substances in the body may also become abnormal. Laboratory tests of blood, cerebrospinal fluid, urine, stool and sputum can indicate the presence of certain tumors. Pathology biopsy: Physical examination, imaging, endoscopy and laboratory tests can show the presence of abnormalities in the body, but only a pathology biopsy can finally confirm whether cancer is present. During a biopsy, the doctor takes a small sample of tissue from the abnormality or removes the entire tumor. The pathologist looks at it under a microscope. If it is determined that cancer is present, the pathologist can usually sort out what kind of cancer it is and can determine how fast or slow that tumor cell is growing. Staging: When cancer is detected, the doctor needs to know the stage of development of the disease i.e. early or late stage. Doctors often need to run a variety of tests to find out if the cancer has metastasized and if so, where in the body. Sometimes lymph nodes near the tumor need to be excised for pathological examination. If cancer cells are found in the lymph nodes, this means that the cancer may have metastasized to other organs in the body. Once the cancer stage is confirmed, the doctor can provide the best treatment plan for the disease.