Acute urinary retention and risk of cancer: population based Danish cohort study.

Objective: To examine the risk of urogenital, colorectal, and neurological cancers after a first diagnosis of acute urinary retention.

Design: Nationwide population based cohort study.

Setting: All hospitals in Denmark.

Participants: 75 983 patients aged 50 years or older with a first hospital admission for acute urinary retention during 1995-2017.

Main Outcome Measures: Absolute risk of urogenital, colorectal, and neurological cancer and excess risk of these cancers among patients with acute urinary retention compared with the general population.

Results: The absolute risk of prostate cancer after a first diagnosis of acute urinary retention was 5.1% (n=3198) at three months, 6.7% (n=4233) at one year, and 8.5% (n=5217) at five years. Within three months of follow-up, 218 excess cases of prostate cancer per 1000 person years were detected. An additional 21 excess cases per 1000 person years were detected during three to less than 12 months of follow-up, but beyond 12 months the excess risk was negligible. Within three months of follow-up the excess risk for urinary tract cancer was 56 per 1000 person years, for genital cancer in women was 24 per 1000 person years, for colorectal cancer was 12 per 1000 person years, and for neurological cancer was 2 per 1000 person years. For most of the studied cancers, the excess risk was confined to within three months of follow-up, but the risk of prostate and urinary tract cancer remained increased during three to less than 12 months of follow-up. In women, an excess risk of invasive bladder cancer persisted for several years.

Conclusions: Acute urinary retention might be a clinical marker for occult urogenital, colorectal, and neurological cancers. Occult cancer should possibly be considered in patients aged 50 years or older presenting with acute urinary retention and no obvious underlying cause.