Prostate cancer and the Will Rogers phenomenon

Area of Science:

• Oncology
• Pathology
• Biostatistics

Background:

• Tumor stage and grade are crucial for cancer prognosis and outcome comparisons.
• Changes in classification interpretation can distort apparent distributions of cancer stage or grade.
• The introduction of prostate-specific antigen testing correlated with a decline in reported low-grade prostate cancer incidence.

Purpose of the Study:

• To investigate if Gleason score reclassification contributed to the observed decline in low-grade prostate cancer incidence.
• To assess the impact of Gleason score reclassification on clinical outcomes between 1992 and 2002.

Main Methods:

• A retrospective cohort of 1858 men diagnosed with prostate cancer (1990-1992) was analyzed.
• Diagnostic prostate histology slides were re-evaluated by a pathologist blinded to original Gleason scores.
• Prostate cancer mortality rates were compared using original versus contemporary Gleason score readings.

Main Results:

• Contemporary Gleason scores were significantly higher than original scores (mean increase from 5.95 to 6.8).
• Gleason score-standardized mortality rates appeared 28% lower with contemporary readings (1.50 vs. 2.08 deaths per 100 person-years).
• This apparent mortality improvement was observed across all Gleason score categories.

Conclusions:

• The decline in reported low-grade prostate cancer incidence is likely due to Gleason score reclassification.
• Reclassification created an artifactual improvement in clinical outcomes, known as the Will Rogers phenomenon.
• This highlights the importance of consistent classification for accurate outcome assessment.