Prostate cancer in South Korea: what the evidence says about who is found late, and what happens next

South Korea is cited around the world as the country that found too much cancer. Its thyroid cancer incidence rose more than tenfold on the back of ultrasound scanning that nobody had asked for, while deaths did not move. This publication has covered that in detail.

Prostate cancer in the same country, over the same period, is the other failure. This article is the summary of what our reporting on it has established, and of the two questions it has repeatedly been unable to answer.

The distribution at diagnosis#

Korea's insurance claims record that a cancer was diagnosed but not how advanced it was, so the national risk distribution was assembled directly, from the clinicopathological records of every biopsy-confirmed case at 51 general hospitals in six sample years between 2010 and 2020.

The trend runs in the wrong direction, and it runs unequally: high-risk disease was 55.4 percent of rural cases and 47.7 percent of urban ones. Only about a quarter of newly diagnosed men were eligible for active surveillance even under a deliberately generous definition, and that share fell over the decade too.

Whether to test#

The randomised evidence on PSA screening is now mature. At 23 years the European trial found prostate cancer mortality 13 percent lower in screened men, an absolute risk reduction of 0.22 percent, one death prevented per 456 men invited — and 30 percent more cancer diagnosed. A single invitation, tested in 415,357 British men, reduced prostate cancer deaths from 0.78 to 0.69 percent at 15 years.

Those trials were designed against overdiagnosis. Korean testing does not look like the thing they tested: among 166,848 men newly registered with prostate cancer, only 26.7 percent had been repeatedly PSA-tested beforehand, and for 42.2 percent the first test came within three months of registration. A first PSA test in the same quarter as the cancer registration is not screening.

Whether to treat, and with what#

At 15 years ProtecT found no significant difference in prostate cancer death between active monitoring, prostatectomy and radiotherapy — 3.1, 2.2 and 2.9 percent, P equals 0.53 — while metastasis and clinical progression were roughly twice as common under monitoring. Of the men assigned to monitoring, 24.4 percent were alive at fifteen years having never been treated at all.

The functional trade is close to an exchange. Surgery does the most lasting damage to continence and erections; radiotherapy largely spares continence and instead affects the bowel, with bloody stools becoming more frequent over time rather than resolving. Korean series report far lower rates than that, for reasons that are mostly about the measuring instrument rather than about Korean patients.

Two Korean findings sharpen the decision rather than restating it. Membranous urethral length, measured on the staging MRI a man has already had, predicts incontinence after robotic prostatectomy at an odds ratio of 0.83 per millimetre — a number available before the choice is made. And which hospital a Korean man attends changes how long he stays on surveillance, without changing what is found if he leaves it.

The two things this evidence does not contain#

Every piece in this coverage ended at one of two absences, and naming them precisely is more useful than another summary of what is known.

1. No Korean dataset records patient-reported continence or sexual function. Korea's national data records diagnosis, treatment and cost. The best Korean functional evidence is clinician-graded toxicity from single institutions, which systematically records less than patients report. Until a Korean series reports patient-reported function at fixed intervals, the trade-off at the centre of this decision is undocumented in Korean practice.
2. Nothing establishes that testing more Korean men would help them. The Korean data is cross-sectional: it describes who was found, in what state, and what was done. The association between repeated testing and localised treatment is stated by its own authors as an association. The randomised evidence on screening was conducted in European and British men.

Korea has spent a decade correcting an epidemic of thyroid cancers that did not need finding. The prostate data raises the parallel question, which has had far less attention: whether the same health system is finding the cancers that do, whether the men it misses are the ones furthest from a hospital, and whether anyone is recording what happens to the men it finds.