Large variation between hospitals and pathology laboratories in lymph node evaluation in colon cancer and its impact on survival, a nationwide population-based study in The Netherlands

Background: Adequate lymph node (LN) evaluation is important for planning treatment in patients with colon cancer. Aims of this study were to identify factors associated with adequate nodal examination and to determine its relationship with stage distribution and survival. Patients and methods: Data from patients with colon carcinoma stages I-III who underwent surgical treatment and diagnosed in the period 2000-2006 were retrieved from the Netherlands Cancer Registry. Multilevel logistic analysis was carried out to examine the influence of relevant factors on the number of evaluated LNs. The relationship with survival was analysed using Cox regression analysis. Results: The number of examined LN was determined for 30 682 of 33 206 tumours. Median number of evaluated LN was 8, ranging from 4 to 15 between pathology laboratories. Females, younger patients, right-sided pN+ tumours with higher pT stage and patients diagnosed in an academic centre were less likely to have nine or less LN evaluated. Unexplained variation between hospitals and pathology laboratories remained, leading to differences in stage distribution. With increasing number of evaluated LN, the risk of death decreased. Conclusion: There was large diversity in nodal examination among patients with colon cancer, leading to differences in stage distribution and being associated with survival.