Oncological Implications of Lymph Nodes Retrieval and Perineural Invasion in Colorectal Cancer: Outcomes from a Referral Center.

Background: In colorectal cancer (CRC), regional lymphadenectomy provides prognostic information and guides management. The current consensus states that at least 12 lymph nodes (LN) should be evaluated. The aims of this study were to identify whether the number of LN is a predictor for survival and recurrence, and to reveal the role of LN ratio (LNR) and perineural invasion (PNI) in predicting prognosis after curative resection of CRC.
Methods: We included all patients who underwent surgery for CRC between 2000 and 2016 in an academic medical center in Mexico. The LNR cutoff value was 0.25. We analyzed two groups according to the number of LN retrieved: Group 1 (≥ 12 LN) and Group 2 (< 12 LN).
Results: We included 305 patients, 13.8% in Stage I, 45.6% in Stage II, and 40.6% in Stage III. The male: female ratio was 1.1. The mean age was 62.6 ± 14 years (range, 19-92). In 233 patients (76.4%), ≥ 12 LN were obtained. Recurrence rates in Groups 1 and 2 were 20.2% versus 26.4%, respectively (p = 0.16). PNI was present in 34 patients (13.2%). An LN harvest < 10 increased local and distant recurrences (p = 0.03). Stage III patients with an LNR ≥ 0.25 had higher overall recurrence rates (p = 0.012) and mortality (p = 0.029). In a multivariate Cox regression analysis, PNI-negative tumors were an independent prognostic factor for disease-free survival (p = 0.011, hazard ratio = 2.78, 95% confidence interval = 1.26-6.16).
Conclusions: An LN retrieval < 10 increased local and distant recurrence rates. LNR was an independent prognostic factor for survival in Stage III tumors. PNI was the only significant independent prognostic factor affecting disease-free survival in our patients.
(Copyright: © 2017 SecretarÍa de Salud.)