Prostate Cancer Staging and Grading
There are two terms that patients should understand regarding the diagnosis and treatment of their cancer: staging and grading. These terms are used by the doctor when it comes to planning treatment, prescribing medications, deciding on surgical treatments or even estimating the likely long-term outcome or course of the disease.
Staging is a way to describe the extent or severity of an individual’s cancer. As the tumor develops, it can invade nearby organs and tissues, or cells can break off and enter the bloodstream or lymphatic system. The cancer then spreads (also called metastasizing) to form new tumors in other organs.
Doctors determine a cancer’s “clinical stage” by using a combination of physical examinations, imaging (such as CT or MRI scans), laboratory tests, biopsies, pathology reports and even physical symptoms a patient describes. If the tumor is removed, microscopic examination by the pathologist often reveals a more complete “pathologic stage”.
Although competing staging systems still exist for some types of cancer, the universally-accepted staging system is that of the “TNM Classification”. The “T” describes the size of the tumor and whether it has invaded nearby tissue, the “N” describes regional lymph nodes that are involved, and the “M” describes distant metastasis (spread of cancer from one body part to another).
Cancer grading (also called tumor grading) is a system used to classify the aggressiveness of cancer cells in terms of how abnormal they look under a microscope and how quickly the tumor is likely to grow and spread. This information can be obtained from a small sample (biopsy) of the tumor. However, as in staging, the information can be more accurate by microscopic examination of the entire tumor following complete removal. For most cancers, grades are described on a scale from 1 to 3 (or 4) from least to most aggressive. However, grading systems can be different for each type of cancer. For example, the Gleason system grades prostate cancer cells on a scale from Grade 6 to Grade 10.
Prostate Cancer Staging:
T1: tumor present, but not detectable clinically or with imaging
T1a: tumor was incidentally found in less than 5% of prostate tissue resected for other reasons
T1b: tumor was incidentally found in greater than 5% of prostate tissue resected for other reasons
T1c: tumor was found in a needle biopsy performed due to an elevated PSA blood test
T2: the tumor can be felt (palpated) on examination, but has not spread outside the prostate
T2a: the tumor is in half or less than half of one of the prostate gland’s two lobes
T2b: the tumor is in more than half of one lobe, but not both T2c: the tumor is in both lobes *
T3: the tumor has spread through the prostatic capsule (if it is only part-way through, it is still T2)
T3a: the tumor has spread through the capsule on one or both sides
T3b: the tumor has invaded one or both seminal vesicles
T4: the tumor has invaded other nearby structures
* It should be stressed that the designation “T2c” implies a tumor which is palpable in both lobes of the prostate. Tumors which are found to be bilateral on biopsy only but which are not palpable bilaterally should not be staged as T2c.