Real-world testing of serum lactate dehydrogenase among patients with metastatic colorectal cancer in the USA.

Background: Serum lactate dehydrogenase (LDH) is a potential prognostic biomarker of outcomes in patients with metastatic colorectal cancer (mCRC). This retrospective, observational study assessed real-world LDH testing patterns and LDH as a prognostic factor for overall survival (OS) in US patients receiving chemotherapy for mCRC.Patients and methods: Patients with mCRC who initiated first-line chemotherapy between January 1, 2016, and November 30, 2022, were selected from a nationwide de-identified Electronic Health Record-derived database. LDH value was categorized based on laboratory reference ranges. The prognostic relationship between pretreatment LDH value and OS was assessed using Kaplan-Meier and multivariate Cox proportional-hazards models.

Results: Of 15 329 adult patients (median age 64 years), 3379 (22%) had LDH testing at or post-index; 21% had abnormal baseline values, while 40% had normal values. Patients with abnormal LDH levels were more likely to be female (47% abnormal LDH vs 41% normal LDH), age ≥65 years (52% vs 49%), African American or Black (12% vs 7%), or reside in the Northeast (30% vs 21%). The median OS (95% CI) in patients with normal baseline LDH was 29.9 (28.3-31.7) vs 16.8 (14.8-18.2) months for those with abnormal LDH. In a multivariate Cox proportional-hazards model, patients with abnormal baseline LDH had higher risk of death (HR 1.91, P < .0001) after adjustment for demographic/clinical characteristics.

Conclusion: Abnormal baseline LDH levels were associated with shorter OS; however, only one-fifth of patients receiving chemotherapy underwent LDH testing. Efforts to increase LDH testing could be valuable in helping guide treatment decisions.