Low anterior resection syndrome is already present in many rectal cancer patients before surgery

• In a Vancouver cohort, 42% (30 of 71) had bowel dysfunction meeting low anterior resection syndrome criteria before treatment.
• By the end of follow-up, 64% had low anterior resection syndrome.
• New-onset symptoms were linked to lower tumor height (p = 0.04). Gut microbiota did not predict who developed them.

Routine pretreatment bowel function assessment is worth doing, so surgeons can counsel patients on expected function. The microbiome findings are hypothesis-generating only: baseline profiles differed, but no bacterial marker predicted later symptoms in this single-center study with a small sample.