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Explainer: How cancer is diagnosed

Tuesday August 6 2019

Cancer

WHO defines cancer as a large group of diseases characterised by the growth of abnormal cells beyond their usual boundaries. PHOTO | FILE | NATION MEDIA GROUP 

ELIZABETH MERAB
By ELIZABETH MERAB
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The World Health Organisation defines cancer as a large group of diseases characterised by the growth of abnormal cells beyond their usual boundaries that can then invade adjoining parts of the body and/or spread to other organs.

What causes cancer?

Cancer arises from the transformation of normal cells into tumours in a multi-stage process that generally progresses from a pre-cancerous lesion to a malignant tumour.

These changes are the result of the interaction between a person's genetic factors and three categories of external agents, including:

  • physical carcinogens, such as ultraviolet and ionising radiation;

  • chemical carcinogens, such as asbestos, components of tobacco smoke, aflatoxin (a food contaminant), and arsenic (a drinking water contaminant); and

  • biological carcinogens, such as infections from certain viruses, bacteria, or parasites.

Doctors often use various tests to find or diagnose cancer.

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They may refer the patient to a specialist or a surgeon but this does not mean that they (patient) has cancer or that she needs surgery.

The sooner the cancer is diagnosed, the better the odds of getting a successful treatment for it.

Diagnosing cancer:

  • BREAST CANCER

Breast self-exam:It's a good idea to know how your breasts normally look and feel so you can notice any changes.

Breast exam: Your doctor will check both of your breasts and lymph nodes in your armpit, feeling for any lumps or other abnormalities.

Breast ultrasound: It involves use of a machine that uses sound waves to make detailed pictures, called sonograms, of areas inside the breast.

Diagnostic mammogram: If you have a problem in your breast, such as lumps, or if an area of the breast looks abnormal on a screening mammogram, doctors may have you get a diagnostic mammogram. This is a more detailed x-ray of the breast. A mammogram can show breast lumps up to two years before they can be felt.

Different tests help determine if a lump may be cancer.

The ones that are not cancerous tend to have different physical features than ones that are. Imaging tests such as mammograms and ultrasounds can often see the difference.

When and if you need these imaging tests is a personal decision between you and your doctor. Most women do not start having mammograms until they're at least 40.

If you are at higher risk for breast cancer, your doctor may want you to start at a younger age.

Magnetic resonance imaging (MRI): This is a kind of body scan that uses a magnet linked to a computer. The MRI scan will make detailed pictures of areas inside the breast.

Biopsy: This is a test that removes tissue or fluid from the breast to be looked at under a microscope and do more testing. There are different kinds of biopsies (for example, fine-needle aspiration, core biopsy, or open biopsy). A biopsy is the only definitive way to make a diagnosis of breast cancer.

During a biopsy, your doctor uses a specialised needle device guided by x-ray or another imaging test to extract a core of tissue from the suspicious area.

Often, a small metal marker is left at the site within your breast so the area can be easily identified on future imaging tests.

Biopsy samples are sent to a laboratory for analysis where experts determine whether the cells are cancerous.

A biopsy sample is also analysed to determine the type of cells involved in the breast cancer, the aggressiveness (grade/stage) of the cancer, and whether the cancer cells have hormone receptors or other receptors that may influence your treatment options.

  • PROSTATE CANCER

It is caused by abnormal cell replication in the prostate — a small walnut-shaped gland in men that produces the seminal fluid that nourishes and transports sperm. 

In Kenya and globally, prostate cancer is one of the most common types of cancer in men.

Most prostate cancers are first found during screening with a prostate-specific antigen (PSA) blood test or a digital rectal exam (DRE).

Early prostate cancers usually do not cause symptoms, but more advanced cancers are sometimes first found because of symptoms they cause.

PSA blood test: The prostate-specific antigen (PSA) blood test is used mainly to screen for prostate cancer in men without symptoms. It is also one of the first tests done in men who have symptoms that might be caused by prostate cancer.

Transrectal ultrasound (TRUS): For this test, a small probe about the width of a finger is lubricated and placed in a rectum.

The probe gives off sound waves that enter the prostate and create echoes. The probe picks up the echoes, and a computer turns them into a black and white image of the prostate.

The procedure often takes less than 10 minutes and is done in the doctor's office or outpatient clinic. You will feel some pressure when the probe is inserted, but it is usually not painful.

The area may be numbed before the procedure.

TRUS is often used to look at the prostate when a man has a high prostate-specific antigen level or has an abnormal digital rectal exam result.

It is also used during a prostate biopsy to guide the needles into the correct area of the prostate.

TRUS is useful in other situations as well. It can be used to measure the size of the prostate gland, which can help determine the PSA density (described in Prostate Cancer Prevention and Early Detection) and may also affect which treatment options a man has.

TRUS is also used as a guide during some forms of treatment such as brachytherapy (internal radiation therapy) or cryotherapy.

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This image shows growth of cancer cells in the prostate. ILLUSTRATION | NATION MEDIA GROUP

Prostate biopsy: If certain symptoms or the results of tests such as a PSA blood test or DRE suggest that you might have prostate cancer, your doctor will do a prostate biopsy.

A biopsy is a procedure in which small samples of the prostate are removed and then looked at under a microscope.

A core needle biopsy is the main method used to diagnose prostate cancer. It is usually done by a urologist, a surgeon who treats cancers of the genital and urinary tract, which includes the prostate gland.

Using TRUS to "see" the prostate gland, the doctor quickly inserts a thin, hollow needle through the wall of the rectum and into the prostate.

When the needle is pulled out it removes a small cylinder (core) of prostate tissue. This is repeated several times. Most urologists will take about 12 core samples from different parts of the prostate.

Though the procedure sounds painful, each biopsy usually causes only a brief uncomfortable sensation because it is done with a special spring-loaded biopsy instrument. The device inserts and removes the needle in a fraction of a second.

Most doctors who do the biopsy will numb the area first by injecting a local anaesthetic alongside the prostate.

You might want to ask your doctor if he or she plans to do this.

The biopsy itself takes about 10 minutes and is usually done in the doctor's office.

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