Background: the prognostic value of the number of lymph nodes isolated (< 12 versus >= 12) in the surgical specimen continues to be controversial. In this study, the impact of isolating fewer or more than 12 lymph nodes in stage II colon cancer with a high-risk biologic phenotype was analyzed, such as the presence of perineural invasion.
Methods: all cases of stage II disease (T3-4N0M0) with perineural invasion (PNI+) were retrospectively identified from a prospective database of patients undergoing surgery for colon cancer. The cohort was divided into two groups depending on the number of lymph nodes isolated (< 12 vs >= 12). Apart from clinical and surgical data, the patterns of recurrence, overall (OS) and disease-free survival (DFS) at five and ten years were analyzed.
Results: sixty patients met the inclusion criteria, 31.7 % had < 12 lymph nodes isolated and 68.3 % had more than 12 isolated. There were no clinical or surgical differences between the two groups. OS at five and ten years was significantly lower in the patients with < 12 lymph nodes isolated (84.2 %, 62.7 % vs 94.6 % and 91.6 %, p = 0.01). DFS at five and ten years was 51 % vs 86.5 %, respectively (p = 0.005).
Conclusion: the number of lymph nodes isolated (with a cutoff of 12) in stage II colon cancer with PNI+ has prognostic value and should therefore be borne in mind when planning adjuvant chemotherapy.