Half of the prostate cancer found in Korea in the 2010s was high-risk, and the rural share was higher still

Prostate cancer has a reputation as the cancer men die with rather than of, built on Western screening populations where most of what gets found is small and slow. Korean national data does not describe that disease. Half of what was found here in the 2010s was high-risk at the moment of diagnosis.

What high-risk meant here#

The criteria were the universal guideline definitions in use through the 2010s: prostate-specific antigen above 20 ng/mL, clinical stage cT3a or beyond, or Gleason grade group 4 or higher. Meeting any one of those puts a man in the high-risk category. These are not marginal thresholds — a PSA above 20 is roughly five times the level that usually prompts a biopsy.

The reason this had not been reported before is worth noting, because it says something about what national databases can and cannot do. Korea's insurance-based registry records that a man has prostate cancer and what was done about it. It does not record his PSA, his clinical stage or his Gleason grade. Producing a risk distribution required abstracting charts from 51 hospitals by hand.

The direction of travel#

Low-risk disease, counting potentially low-risk cases with it, fell from 11.4 percent of diagnoses in 2010 to 7.6 percent in 2020. Over a decade in which testing became more available, not less, the share of mild disease being caught went down by a third.

The rural gap#

High-risk disease was the most prevalent category in 9 of 17 administrative regions, and 55.4 percent of high-risk cases came from rural residents against 47.7 percent from urban ones. The authors attribute this to differences in access to early detection, and the alternative explanations are thin: there is no reason for prostate cancer to be biologically more aggressive outside cities in a population this genetically homogeneous.

One limit cuts against reading the rural figure as too clean. The cohort was drawn from hospitals with 200 or more beds, which are themselves concentrated in cities, so rural men in this dataset are those who reached a large hospital. If anything that selects for the better-connected end of the rural population, which would understate rather than exaggerate the gap.