Only a quarter of Korean prostate cancer is eligible for active surveillance — and the share fell across the decade

Active surveillance is the option that lets a man with prostate cancer not be treated for it — monitored instead, with treatment held in reserve. How often it is genuinely available depends on how much of the disease being found is mild enough to watch, and until this analysis nobody had counted that in Korea.

Why the number is an upper bound#

The authors did not use a conservative definition and then report a small figure. They did the opposite: eligibility was defined as the union of low risk, potentially low risk and favourable intermediate risk, which is the widest defensible reading of who could be watched rather than treated. Under the narrower definition most guidelines have used historically — low risk alone — the figure would be 5.45 percent, with another 4.00 percent potentially low risk.

That framing matters when the number is quoted. One in four is the ceiling, not the estimate. Anyone arguing that Korean practice under-uses surveillance has to work inside that ceiling.

The trend runs the wrong way#

Eligibility fell from 27.6 percent in 2010 to 22.0 percent in 2020. In a country where screening intensity was rising over the same period, the expected direction is the opposite: more testing usually means more small, indolent cancers found, which means more men eligible to be watched. Korea moved the other way, which says the disease being detected got worse rather than milder over the decade.

Where a man lives changes the answer#

Eligibility ranged from 16.9 percent in Chungbuk to 29.3 percent in Gyeonggi — a spread of more than twelve percentage points between provinces in a country with one national insurer and one set of guidelines. Urban districts came in at 26.4 percent against 20.5 percent in rural ones.

This is not a finding about treatment preference. Eligibility was calculated from the tumour: prostate-specific antigen, clinical T stage, Gleason grade group and biopsy core involvement. A man in Chungbuk is less likely to be eligible because his cancer is further along when it is found, not because his urologist thinks differently about surveillance.

One structural caveat is worth carrying. The cohort is chart-abstracted from 51 general hospitals and covers 37.9 percent of nationally reported cases, so it is a large sample rather than a complete census, and hospitals with 200 or more beds are not evenly distributed across the country either. That works against the rural figures being flattering, not for them.