Key clinical point: After considering time-related biases such as immortal time bias (ITB) , metformin use is nonsignificantly associated with subsequent colorectal cancer (CRC) incidence in patients with type‑2 diabetes (T2D).
Major finding: Time-dependent Cox regression, landmark, or nested case-control analysis did not reveal a significant association between metformin use and CRC incidence, with hazard ratios (95% CI) for metformin ever-use (≥90 days of metformin prescription throughout follow-up) being 0.88 (0.68-1.13), 0.86 (0.65-1.12), and 1.10 (0.86-1.40), respectively, and those for average metformin prescription days/year being 0.97 (0.90-1.04), 0.95 (0.88-1.04), and 1.02 (0.95-1.10), respectively.
Study details: This observational study employed statistical methods that avoid ITB to analyze the real-world data of 41,533 patients newly diagnosed with T2D who were cancer-free at T2D diagnosis from a prospectively maintained cohort.
Disclosures: No source of funding was disclosed. The authors reported no conflicts of interest.
Source: Zhang HS et al. Metformin use is not associated with colorectal cancer incidence in type-2 diabetes patients: Evidence from methods that avoid immortal time bias. Int J Colorectal Dis. 2022;37:1827–1834 (Jul 14). Doi: 10.1007/s00384-022-04212-9