Diagnosis

The diagnosis of cancer involves an attempt to accurately identify the location in the body where the cancer originated, the type of cells involved in the malignancy, and the severity of the condition.

The body part in which cancer first develops is known as the primary site, and the cancer is labeled according to this location, regardless of whether the cancer spreads to other areas. The secondary site refers to the body part(s) where cancer cells have spread, or metastasized. The most common primary sites include the skin, lungs, breasts (in females), prostate, colon and rectum, and uterus. A cancer's primary site may determine how the tumor will behave, the likelihood that it will spread, and the probable symptoms that it will cause (1).

There are many signs and symptoms that are associated with the presence of cancer. These may be observed through a physical examination, imaging technologies such as a CT scan, or confirmed by lab tests taken from blood, urine samples, or tissue sample (1). Tissue samples are typically examined under a microscope by a pathologist in what is known as a histological exam. The histological exam of biopsied tissue (i.e., tissue that has been extracted from the body) is the most definitive method of confirming cancer (1, 2).

Once a diagnosis of cancer has been confirmed, a pathologist categorized cells based on how "aggressive" the tissue appears under a microscope. The more aggressive the tissue, the less the cancer cells appear to resemble healthy cells, which indicates a higher level of malignancy. Malignant cells are rated according to Grades 1-4: Grade 1 is also known as "well differentiated," and it means that the cancer cells appear similar to their healthy counterparts. Grades 2 and 3 are "moderately differentiated" and "poorly differentiated," respectively. Grade 4 indicates that the cells are "undifferentiated," which means that the cells are unlike healthy cells, and are highly malignant (1, 3).

The cancer diagnosis also involves classifying the condition according to stage, which describes how far the cancer has progressed in terms of size and where, if anywhere, it has spread. Depending on the cancer and the classification system, there are typically four stages of cancer, with Stage 1 being the least severe, and Stage 4 indicating that the tumor has grown and spread to an advanced stage (4).

'Diagnosis' Sources:
  1. "Cancer Diagnosis." From Cancer as a Disease, a training module from the U.S. National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) program. Available: http://training.seer.cancer.gov/module_cancer_disease/unit4_cancer_diagnosis.html (Accessed July 18, 2007).
  2. "Histology." From the National Cancer Institute's Dictionary of Cancer terms. Available: http://www.cancer.gov/Templates/db_alpha.aspx?CdrID=44171 (Accessed July 18, 2007).
  3. "Undifferentiated Cancer." From Medterms.com. Available: http://www.medterms.com/script/main/art.asp?articlekey=20476 (Accessed July 18, 2007).
  4. "The Stages of Lung Cancer." From Cancerhelp.org.uk. Available: http://www.cancerhelp.org.uk/help/default.asp?page=6706 (Accessed July 18, 2007).

 

 

 

 

 
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