Prostate cancer is common, but its aggressiveness varies. Some grow slowly, while others spread quickly. Understanding this variation is crucial for treatment decisions. This article explains how prostate cancer aggressiveness is classified and its prevalence.
Understanding Aggressiveness
Prostate cancer aggressiveness is determined by examining biopsy tissue. Pathologists analyze cell patterns under a microscope, assigning a Gleason score. This grading system adds two primary patterns, ranging from 6 to 10. For example, 3+3=6 indicates less aggressive cancer, while 4+5=9 signifies a more aggressive form.
A modern system, the Grade Group, is often used with or instead of the Gleason score for clearer communication. Grade Groups range from 1 to 5, correlating with specific Gleason scores. Grade Group 1 (Gleason 6) represents the least aggressive cancers. Grade Group 2 and 3 align with Gleason 7 (3+4 and 4+3), indicating intermediate aggressiveness.
Higher Grade Groups, like Grade Group 4 (Gleason 8) and Grade Group 5 (Gleason 9-10), denote more aggressive cancers. While Gleason score and Grade Group are central, other factors contribute to risk assessment. These include prostate-specific antigen (PSA) level at diagnosis and clinical stage (T-stage), which describes cancer extent within or beyond the prostate. These factors help categorize cancer into specific risk groups.
Prevalence of Aggressive Prostate Cancer
The proportion of aggressive prostate cancers varies by definition. Using the common risk stratification system, cancers are grouped into low, intermediate, and high-risk categories. Low-risk prostate cancer (Gleason 6/Grade Group 1, PSA below 10 ng/mL, confined to prostate T1 or T2a) accounts for a large portion of new diagnoses, around 40% to 50%. These are considered non-aggressive or indolent.
Intermediate-risk prostate cancer includes Gleason 7 (Grade Group 2 or 3) and/or PSA between 10-20 ng/mL, or extensive T2 disease. This represents a large group, with about half of diagnoses falling into this category. This group is further divided into “favorable” and “unfavorable” intermediate risk, based on specific Gleason patterns (e.g., 3+4 vs. 4+3) and biopsy core involvement.
High-risk prostate cancer is defined by Gleason 8-10 (Grade Group 4 or 5), PSA above 20 ng/mL, or cancer spread slightly beyond the prostate (T3 or T4). This aggressive form accounts for about 15% to 20% of all diagnoses. While most prostate cancers are not aggressive, these statistics show a significant percentage of men face a challenging form of the disease.
Factors Affecting Aggressiveness
Several factors contribute to prostate cancer aggressiveness. Age is a factor; incidence increases with age, with most diagnoses in men over 65.
PSA level at diagnosis is another indicator. Higher PSA levels are associated with a higher likelihood of more advanced or aggressive disease. Similarly, clinical stage, describing tumor extent within or beyond the prostate, reflects aggressiveness.
Genetic and hereditary factors also influence aggressiveness. A strong family history, especially if relatives were diagnosed young, increases the risk of aggressive cancer. Certain inherited genetic mutations, like BRCA1 or BRCA2, are linked to a higher risk of aggressive prostate cancer. Race is also a factor; African American men have a higher risk of aggressive prostate cancer and are often diagnosed younger.
Why Aggressiveness Matters
Understanding prostate cancer aggressiveness is important because it influences treatment decisions and prognosis. For low-risk, less aggressive cancers, active surveillance is a suitable strategy. This involves monitoring cancer progression through regular PSA tests, digital rectal exams, and occasional biopsies, allowing men to avoid or delay treatment and its side effects.
Conversely, more aggressive cancers require immediate and intensive treatments, such as radical prostatectomy or radiation therapy, sometimes with hormone therapy. The goal is to eradicate cancer before it spreads widely, which would worsen the prognosis. Understanding aggressiveness helps tailor the treatment plan to the tumor’s characteristics.
Prognosis, or the likely course of the disease, is tied to aggressiveness. Less aggressive cancers have good long-term outcomes, with many men never experiencing health issues from their cancer. More aggressive cancers, if untreated or resistant to treatment, carry a higher risk of progression, metastasis, and a less favorable prognosis. Aggressiveness also dictates the intensity and frequency of post-treatment monitoring and follow-up care.