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How Is Cancer Diagnosed?

Expertly reviewed by Dexter Macalintal, MD · Internal or General Medicine

Written by Samantha Beltran · Updated Mar 10, 2022

    How Is Cancer Diagnosed?

    In the Philippines, cancer is the third leading cause of death. According to the World Health Organization (WHO) 141,021 cases of cancer were diagnosed in 2018. Worldwide, cancer continues to be the second leading cause of death, with 9.6 million lives lost to the disease in 2018. How is cancer diagnosed? And how can early detection potentially be life-saving?

    What Is Cancer?

    Our bodies normally produce cells that grow and divide. Some cells die when they get too old or damaged, then the body creates new cells. Cancer is a medical term used to describe diseases where some of the body’s cells grow and divide uncontrollably. There are over 100 types of cancer that affect different parts of the body, as cancerous cells can also spread to other organs. 

    When cells overproduce, they can form a mass called a tumor, which can be either benign (non-cancerous) or malignant (cancerous). When a tumor is malignant, it can grow and spread to other parts of the body. Meanwhile, there are other types of cancer that do not develop tumors, such as leukemia.

    There are certain risk factors that can influence your chances of getting cancer. While these factors do not directly cause cancer, having one or more of these risk factors should encourage you to go for regular cancer screening. This allows for early detection and treatment of cancer before it develops into a more severe stage. Some common risk factors are:

    • Age
    • Alcohol consumption
    • Obesity
    • Family history
    • Diet and lifestyle habits
    • Smoking
    • Present health conditions
    • Environment

    How Is Cancer Diagnosed?

    Most people who develop cancer have no symptoms. Thus, by the time they feel something different in their bodies, the cancer has already progressed to a more advanced stage. This is why regular screening is important for early detection and diagnosis, and to improve your chances of recovery.

    How is cancer diagnosed? According to the American Cancer Society, there are three tests doctors commonly use to diagnose cancer.

    1. Imaging tests

    Imaging tests help doctors examine conditions in the body through X-ray energy, sound waves, radioactive particles, and magnets. The resulting image can help doctors see whether a certain body condition may be a malignant or benign tumor.

    This examination is particularly useful in helping detect early-stage cancer, determining the size and location of the tumor, and seeing whether it has spread to other areas. Patients will have to undergo imaging tests more than once to help the doctor see how the tumor is progressing within the treatment period and determine whether the cancer treatment is effective or not.

    There are several types of imaging tests for cancer diagnosis. These include:

    CT scan

    A computed tomography scan or CT scan helps doctors find the location, shape, and size of the cancer. This scan is typically an outpatient procedure, as it is painless and only takes between 10 to 30 minutes.

    This scan shows a clearer cross-section of the body, including bones, organs and soft tissues compared to a standard X-ray. It will even show the blood vessels that feed the tumor without having to perform surgery.

    A CT scan uses a pencil-thin beam to create a series of images that are displayed on a computer screen. Possible side effects after the examination include skin rashes, nausea, shortness of breath and wheezing, and the itching or swelling of the face for more than 1 hour.


    Magnetic resonance imaging or MRI is a test that helps doctors find the location and spread of cancer within the body. MRI results also help doctors determine the best treatment plan, such as surgery or radiotherapy.

    The MRI uses magnetic energy and radio frequency waves to capture images of the material that, inserted into the body through a vein. The MRI test typically lasts between 45 to 60 minutes, but can also last as long as 2 hours.

    A special breast MRI particularly targets and checks for breast cancer. Side effects of an MRI that may occur are:

    • Nausea
    • Pain at the injection site
    • Headaches that appear a few hours after the test
    • Dizziness due to a decrease in blood pressure


    An X-ray exam helps doctors find cancer cells in the bones, abdominal organs, and kidneys. Although CT scans or MRIs show more detailed results, X-rays are just as fast, easy, and are a more affordable option in diagnosing certain cancers.

    In this procedure, the use of an iodine-based contrast material, such as barium, is useful for making the organs visible on X-rays more clearly. One type of X-ray examination is mammography as a breast cancer screening test. Depending on the contrast method, the duration of the examination can take from 5 minutes to 1 hour.

    The side effects of this cancer test include a burning sensation in the injection area, nausea, vomiting, and changes in the sense of taste.

    Nuclear Scan

    Nuclear imaging can help doctors find the location and extent of cancer spread. There are several types of nuclear scans that can detect cancer. These are bone scans, PET scans, thyroid scans for thyroid cancer, MUGA (multigated acquisition) scans, and Gallium scans.

    This cancer diagnostic test creates images based on body chemistry like other imaging tests, using liquid radionuclides.

    That said, this nuclear scan is often unable to detect tumors that are very small in size.

    The duration of the examination takes 20 minutes to 3 hours, with side effects including swelling and pain at the injection site and allergic reactions.


    If the results of the X-ray are not clear, the doctor will recommend an ultrasound to find the location of the cancer. This scan uses high-frequency sound waves that pass through the body to produce images. In some cases, an ultrasound is also useful for differentiating between a cyst and ovarian cancer.

    A doctor or technician conducts an ultrasound by applying a special liquid on the surface of the skin and attaching the transducer. They then insert this tool into the esophagus, rectum, or vagina.

    That said, ultrasound images are not as detailed as CT or MRI scans, and sound waves also cannot penetrate the lungs and bones. An ultrasound is a safe test and has very little risk of side effects.

    All tests for cancer screening through scanning are very helpful. But due to their limitations, your doctor may also perform other screening tests.

    2. Endoscopic Procedures

    How is cancer diagnosed? At times, your doctor may employ endoscopic procedures. An endoscopy is a medical procedure that inserts a tube-shaped instrument into the body to see what’s inside. There are several types of endoscopic procedures, such as:

    • Bronchoscopy which aims to look for blockages in the airways such as tumors
    • Colonoscopy, which is useful for finding out the cause of drastic weight loss, bleeding in the rectum, or changes in bowel habits
    • Laparoscopy, which helps determine the cause of hip pain and take tissue samples in tumors for cervical cancer, ovarian cancer, and uterine cancer
    • Cystoscopy, which helps determine the presence of cancer in the bladder and urethra and guides the removal of small tumors in these areas

    3. Biopsy

    A biopsy is a procedure that takes a piece of tissue to examine your body cells. This test is very accurate and the result is a definite diagnosis of cancer. Therefore, a biopsy is often a combination of other cancer screening tests.

    There are several types of biopsy tests, including:

    Bone Marrow Biopsy

    Doctors will recommend this test if they detect abnormalities in the blood or suspect that the cancer has spread to the spinal cord. This test can detect cancers such as leukemia, lymphoma, and multiple myeloma.

    During a bone marrow biopsy, the doctor takes a sample of bone marrow from the back of the hipbone using a long needle. In some cases, your doctor may perform a marrow biopsy from another bone in the body. You will receive a local anesthetic before the bone marrow biopsy to minimize discomfort during the procedure.

    Endoscopic Biopsy

    Biopsy cancer test using an endoscope, a thin flexible tube that helps examine the inside tissue of the body.

    Needle Biopsy

    Needle biopsies are often performed on tumors that doctors can feel through your skin. These include breast lumps and enlarged lymph nodes.

    When combined with an imaging procedure, such as an X-ray, a needle biopsy can collect cells from suspicious areas that are not felt through the skin.

    You will receive a local anesthetic to numb the area for biopsy and minimize pain.

    Surgical Biopsy

    During a surgical biopsy, the surgeon makes incisions in the skin to access areas of suspicious cells. For example, removing a breast lump which may be a symptom of breast cancer and removal of a lymph node which may be a lymphoma.

    Your doctor may recommend surgical biopsy procedures to remove part of the abnormal cell area (incision biopsy) or remove the entire area of ​​abnormal cells (excisional biopsy).

    Some surgical biopsy procedures require general anesthesia to keep you unconscious during the procedure. Your doctor may also ask that you remain in the hospital for observation after the procedure.

    How is cancer diagnosed? The procedures above detail various methods to detect cancer. What’s important to remember is that regular screening is an important part of taking care of your health, especially if you are at risk of cancer. Consult your doctor for more information.

    Learn more about Cancer here


    Hello Health Group does not provide medical advice, diagnosis or treatment.

    Expertly reviewed by

    Dexter Macalintal, MD

    Internal or General Medicine

    Written by Samantha Beltran · Updated Mar 10, 2022

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