Diagnosis is not the same as detection. Cancer may be detected when symptoms or abnormalities, such as a lump or growth, are recognized by a patient or physician. After cancer is detected, it still must be carefully diagnosed.
A diagnosis is an identification of a particular type of cancer.
When making a diagnosis, the initial signs and symptoms are investigated through a variety of tests in order to identify whether cancer is causing them and, if so, what type of cancer it is. For example, breast cancer may be detected when a patient notices a lump, but it must be carefully evaluated with a number of tests in order to determine an accurate diagnosis. The diagnosis describes what type of breast cancer it is (i.e., ductal if it started in the ducts of the breast or lobular if it started in the lobes) and how advanced it is.
Diagnosing cancer involves the use of a variety of tests that provide details about abnormal cells, which may have been detected through routine medical examinations, self-examination, or reported symptoms. More information about these cells must be gathered in order to identify them as malignant (cancerous) or non-malignant (non-cancerous), and if they are malignant, to determine how serious (aggressive) the particular cancer cells are. Aggressive cancers grow and spread more quickly than less-aggressive or indolent cancers.
There are many types of tests specifically designed to evaluate cancer:
A pathology report is based on observation of abnormal cells under a microscope.
Diagnostic imaging involves visualization of abnormal masses using high-tech machines that create images, such as X-rays, computed tomography (CT), positron emission test (PET), magnetic resonance imaging (MRI), and combined PET/CT.
Blood tests measure substances in the blood that may indicate how advanced the cancer is or identify other problems related to cancer.
Tumor Marker Tests
Tumor marker tests detect substances in the blood, urine, or other tissues that occur in higher than normal levels of certain cancers.