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Diagnosis is the process of finding the underlying cause of a health problem. If cancer is suspected, the healthcare team will confirm if it is present or not, and what type of cancer it is.

The process usually begins with a person visiting their family doctor with a specific complaint or symptom or because something was detected during a routine check-up. After taking a medical history and performing a physical examination, the doctor will come up with a list of potential causes for the problem, usually referred to as a differential diagnosis. Tests (for example, laboratory tests, x-rays), procedures or an appointment with a specialist will help doctors determine the exact diagnosis. The diagnosis of cancer almost always requires an examination of a tissue sample from an abnormal area (biopsy). Examining this tissue can confirm whether or not cancer is present and also what type of cancer it is.

Diagnostic tests are usually done in a typical order, but the tests that are done and when they are done can vary. Diagnostic tests are used to:

  • confirm the presence of cancer
  • identify the type of cancer
  • identify the grade of the cancer (how abnormal the cells look and behave)
  • find the site where the cancer started (primary tumour)
  • determine the stage of the cancer (how far the cancer has progressed)
  • help plan cancer treatment
  • monitor response to treatment
  • help determine if cancer has returned (recurred)

Many factors can affect test results and what is considered normal for one person may not be the same for another person. The doctor will interpret the test results with the person’s overall health and individual situation in mind.

The process of diagnosis may seem long and frustrating, but it is important for the doctor to rule out other possible reasons for a health problem before making a cancer diagnosis.


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Cancer information in over a hundred languages

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The Canadian Cancer Society’s Cancer Information Service (CIS) is Canada’s only national, bilingual, toll-free service that offers personalized comprehensive cancer information in over 100 languages.

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