The Gleason Score for Prostate Cancer

The Gleason Score

Following a positive prostate biopsy result, the Gleason score is used to evaluate a patient’s risk levels and to determine the aggressive nature and overall significance of their prostate cancer. The Gleason score consists of staging and grading measures; these are used to assess cancer concentration levels and to identify appropriate treatment courses. A Pathologist will study a sample of the patient’s prostate cells using a microscope and following the staging and grading procedures, a Gleason score will be calculated and applied to patients, using PSA readings, the patient’s individual family history and any other relevant factors known to impact the assessment.

Gleason Score for Prostate Cancer
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Because an array of varying prostate cancers exist with varying levels of growth or aggression, this specific personal information can help determine the time-sensitivity of required treatment. The more aggressive the cancer, the sooner treatment is needed; slower developing cancer is more likely to be deemed less significant or non-urgent.

Gleason score staging¹

The Gleason score ultimately measures and assesses the aggressive nature of a tumour and its growth rate, adding together the two most common cell types within a tumour and scoring them from one to five. Staging and grading converts the size and scope of cancer, and the capacity to grow both within and beyond the prostate, with a ‘TNM’ score.

What are the TNM values? Tumour measurements are referred to as the T value. Cancer spreading to pelvic lymph nodes is referred to as the N value. Cancer that’s spread into others organs and beyond the prostate is referred to as the M value. TNM staging is scored between T1 and T4, as outlined below…

T values: T1- prostate-specific cancer that’s too small to feel or identify during diagnosis. T2- prostate-specific cancer that can be felt. T3- cancer growth beyond the prostate, but yet to attach to other tissues. T4- cancer growth beyond the prostate which has attached to other tissues. Then there’s the N value…

N values: Dependent on cancer sizes found in pelvic lymph nodes or other organs beyond the prostate, Urologists will give the disease an N level of 0-3. N1 equates to cancer/tumour sizes of 2cm or less, whereas N3 reflects cancer growth of 5cm or more. Finally, there are the M vales to be applied….

M values: The M stage disease value is determined and rated as being either zero, M1a, M1b or M1c; this is subject to whether or not the cancer has spread beyond the lymph nodes. When determining the severity of cancer, combining the T, N and M staging values provides a Gleason score that’s then subject to grading.

Gleason score grading¹

Gleason scores of six+ represent slow-growing low-level cancer, whereas scores above eight+ represent the opposite. Younger patients, high Gleason scores or late-stage cancer development usually dictate treatment, whereas elderly patients, low Gleason scores or early-stage cancer usually involve active monitoring; anything between is moderate.

Because early-stage cancer with high PSA levels can develop quicker than late-stage cancer with lower PSA levels, a patient’s PSA level may be re-measured, alongside the staging and grading phases, so as to monitor prostate cancer development. By combining PSA readings with Gleason scores and grading, prostate cancer risk assessments can be conducted.
A patient’s personal preference regarding treatment is essential and doctors will consider this aspect when determining the cancer risks of individual cases. Alongside the inherent side-effects, the risks of non-treatment or the dangers of succumbing to other diseases or illnesses will also be evaluated and thoroughly considered.

¹Cancer Research UK, Gleason score and Grade Groups, 31 May 2019

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