BACKGROUND: Lymphovascular invasion (LVI) plays an important role in determining the risk of lymph node metastasis (LNM) in T1 colorectal cancer (CRC) patients and influencing treatment decisions and patient outcomes. OBJECTIVE: This study evaluated how the detection of LVI varies between Dutch laboratories and investigated its impact on the treatment and oncological outcomes of T1 CRC patients. METHODS: Pathology reports and clinical data of T1 CRC patients who underwent local resection between 2015 and 2019 were obtained from the Dutch nationwide pathology databank (Palga cohort, n = 5513). Data on the standard of LVI diagnosis (H&E/Immunohistochemistry) were not available. We categorized laboratories as low, average, or high detectors and evaluated the impact of LVI detection practice on the surgical resection rate and the proportion of LNM-negative (LNM-) surgeries. In the second part of the study, we used the Dutch T1 CRC Working Group cohort (n = 1268) to evaluate the impact of LVI detection practice on cancer recurrences during follow-up. Multivariable logistic regression analyses and Cox proportional hazard regression were used to study the association between LVI detection practice and the outcomes. RESULTS: In the PALGA cohort, the proportion of surgical resections after local resection of a T1 CRC was significantly higher among patients diagnosed by laboratories with a high LVI detection rate (high vs. low: adjusted OR [aOR] 1.87; 95% confidence interval [CI] 1.52-2.31) as was the proportion of LNM-surgeries (aOR 1.73; 95% CI 1.39-2.15). In the second cohort, no significant difference was observed in cancer recurrences among patients diagnosed in laboratories with high detection rates compared with low detection rates (aHR 2.23; 95% CI 0.94-5.23). CONCLUSION: These findings suggest that a high detection rate of LVI does not improve oncological outcomes and may expose more patients to unnecessary oncological surgery, emphasizing the need for standardization of LVI diagnosis.