Staging and Grading

N Stages

N followed by 0 to 3 refers to whether the cancer has reached the regional lymph nodes, which are located next to the prostate in the pelvic region.

M Stages

M stages refer to metastasis (tumors developing outside the prostate).

Jewett Staging System

The stages in the Jewett system are roughly equivalent to the stages in the TNM system as follows:

The Gleason Grading System

Tumors are assigned scores according to a scale known as the Gleason system, which measure how well or how poorly organized they are under the microscope. The first step is to grade the tumors:

• Grade 1: Single, well-packed tumors
• Grade 2: Single, more loosely arranged and less uniform tumors
• Grade 3: Single tumors of different sizes and patterns, with cellular breakdown becoming increasingly worse
• Grade 4: Irregular tumor masses, fused together; may show clear cells
• Grade 5: The tumors have broken down and cellular structure has markedly deteriorated

Two-thirds of prostate cancers have a mix of tumor grades. To determine a prognosis, two numbers are assigned, representing the dominant grade and then the minor grade. The cancer is then "scored" by adding the dominant grade plus the minor grade. For example, a tumor with a dominant grade of 3 and a minor grade of 4 are given a Gleason score of 7. The following scores are often used to suggest how well or poorly the tumor is differentiated. The higher the score, the more severe the break-down of their cellular structure and the more likely they are to spread aggressively:

• Score 2-4: Well-differentiated. Indicates about a 95% chance for surviving 15 years without aggressive treatment.
• Score 5-6: Moderately well differentiated. Slightly lower chance of survival that decreases with time.
• Score 7-10: Moderately poorly to poorly differentiated, with 15-year survival rates of 15 - 40%.