Basics of cancer diagnostics

If you are suspected of having cancer based on your symptoms or the results of an early cancer screening test, your doctor will refer you for further testing. The testing will include a physical exam that includes a personal and family medical history, laboratory tests, imaging tests, and other diagnostic tests if necessary. In most cases, a biopsy will be needed to definitively confirm the diagnosis.

Laboratory tests. Too high or too low levels of certain substances in the blood, urine, or other fluids can help make a diagnosis. However, abnormal laboratory tests are not a sure sign of cancer (and vice versa, normal blood tests do not rule out cancer). For some tumors, the analysis of tumor markers is important, which you can read about in a separate article.

Imaging tests. These include techniques that create images that can help the doctor detect whether a tumor is present. There are several types of imaging tests used in oncology. Computed tomography (CT) uses x-rays to take a series of pictures of a specific part of the body from multiple angles. Often, oral or intravenous contrast is administered before the scan to increase the accuracy of the images. During the scan, the patient lies still on a table that slides through the scanner tunnel. Magnetic resonance imaging (MRI) uses powerful magnets and radio waves to produce images of layers of a specific part of the body. During the scan, the patient lies on a table that enters a long chamber. The MRI machine makes loud thumping sounds and rhythmic beats. As with CT, a contrast agent may sometimes be used to better visualize tumors. The advantage of MRI over CT is that there is no radiation to the patient or staff.

Nuclear medicine techniques. These imaging techniques use radioactive material, and are therefore also called radionuclide techniques. Before the scan, the patient is injected with a small amount of a radioactive substance (tracer), which travels through the bloodstream and accumulates in certain organs or tissues. During the scan, the patient lies on the table while the scanner detects radioactivity in the body. The radioactive material loses activity over time or is excreted in the urine or stool and does not pose a risk to the patient.

Bone scan. One of the most commonly used nuclear medicine tests in oncology. It uses a radioactive substance that specifically accumulates in bones and can detect abnormal areas in the bones. It is used in the diagnosis of bone tumors or (more often) metastases of a tumor to the bone.

Positron emission tomography (PET) and PET/CT. A nuclear medicine test that uses radioactively labeled glucose to detect cancer. The test exploits the property of malignant tumors to take up more glucose (sugar) from the blood than healthy cells. The test is performed similarly to other nuclear medicine imaging techniques, and is often combined with CT, in which case the hybrid test is called PET/CT.

Figure 1. A view of a modern CT device. CT is one of the most widely used imaging tests in oncology today, and can be used to make a diagnosis, monitor the effect of treatment, and follow up with patients after therapy.

Ultrasound. Ultrasound uses high-energy sound waves that the human ear cannot hear. The sound waves bounce off the tissue they encounter, and a computer records the reflected waves to create an image of the tissue.

X-ray. X-rays use a low dose of radiation to create an image of a specific part of the body. Unlike CT, which takes a large number of slices and thus allows for high-precision images, X-rays generally take images of the patient in one or two planes, giving a two-dimensional view of a specific region.

Biopsy. In most cases, a biopsy is necessary to confirm a cancer diagnosis. The doctor takes a piece of tumor tissue, and then a pathologist confirms or rules out the diagnosis of cancer under a microscope based on the appearance of the cells and other tests. Pathology plays a major role not only in diagnosis but also in treatment, because depending on certain molecular characteristics of the tumor, the patient may be a candidate for various types of treatment. A biopsy can be done in several ways. Using a needle, the doctor takes a sample of tissue or fluid (for example, bone marrow aspiration, cerebrospinal fluid puncture, some breast, prostate, and liver biopsies). Another form is endoscopy, where an endoscope (a long, thin tube with a camera) is used to examine places inside the body (for example, in a colonoscopy, the endoscope is inserted into the anus and the intestine is examined; in a bronchoscopy, the endoscope is inserted through the mouth or nose and the lungs are examined; in a gastroscopy, the endoscope is inserted through the mouth and the esophagus and stomach are examined). If the doctor sees suspicious tissue, endoscopy allows it to be removed at the same time or a sample to be taken for pathological analysis. A third way to obtain a tissue sample is through surgery. An excisional biopsy, in which the surgeon removes the suspicious growth in its entirety, or an incisional biopsy, in which only part of the growth is removed.

What after the diagnosis is made? After the diagnosis of cancer is confirmed, additional tests and examinations are often needed to define the stage of the disease and make a decision about treatment. Tumor tissue can also be sent for genetic testing to obtain more information about the possibilities of using certain groups of drugs.

Additional interesting facts

Many patients ask how it is possible that they are sick, and periodic blood count checks have always been without significant deviations? Unfortunately, in the blood count itself, we usually cannot find signs of malignant disease, with the exception of hematological diseases such as leukemia. Anemia can be observed in a certain number of patients with cancer, for example in patients with colon cancer because these tumors can lead to continuous minor bleeding and thus blood loss that over time can lead to anemia. However, most patients do not have deviations in their blood count that could be a sign of cancer development, and it is difficult to suspect the disease just by checking the blood count. Do you have symptoms that do not go away for a long time? Do not neglect your health. Contact our team for an examination!

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What are tumor markers?

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