Prognostic Value of Lymph Node Ratio in Locally Advanced Rectal Cancer Patients After Preoperative Chemoradiotherapy Followed by Total Mesorectal Excision

Abstract

Although the absolute number of positive lymph nodes (LNs) has been established as 1 of the most important prognostic factors in rectal cancers, many researchers have proposed that the lymph node ratio (LNR) may have better predicted outcomes. We conducted a retrospective study to compare the predictive ability of LNR and ypN category in rectal cancer.A total of 264 locally advanced rectal cancer (LARC) patients who underwent preoperative chemoradiotherapy (CRT) followed by total mesorectal excision (TME) between 2005 and 2012 were reviewed. All patients were categorized into 3 groups or patients with metastatic LNs were categorized into 2 groups according to the LNR. The prognostic effect on overall survival (OS) and disease-free survival (DFS) was evaluated.With a median follow-up of 45 months, the OS and DFS were 68.4% and 59.3% for the entire cohort, respectively. The respective 5-year OS and DFS rates for the 3 groups (LNR = 0, 0 < LNR ≤ 0.20, and 0.20 < LNR ≤ 1.0) were as follows: 83.2%, 72.6%, and 49.4% (P < 0.001) and 79.5%, 57.3%, and 33.5% (P < 0.001), respectively. Multivariate analysis revealed that LNR and differentiation, but not the number of positive LNs, had independent prognostic value for OS (hazard ratio [HR] = 2.328, 95% confidence interval [CI]: 1.850–4.526, P < 0.001) and DFS (HR = 3.004, 95% CI: 1.616–5.980, P < 0.001). As for patients with positive LNs, the respective 5-year OS and DFS rates for the 2 groups (0 < LNR ≤ 0.20, and 0.20 < LNR ≤ 1.0) were 72.6% and 49.4% (P < 0.001) and 57.3% and 33.5% (P < 0.001), respectively. Multivariate analysis revealed that only LNR was an independent factor for OS (HR = 3.214, 95% CI: 1.726–5.986, P < 0.001) and DFS (HR = 4.230, 95% CI: 1.825–6.458, P < 0.001). Subgroups analysis demonstrated that the ypN category had no impact on survival whereas increased LNR was a significantly prognostic indicator for worse survival in the LNs < 12 subgroup.LNR is an independent prognostic factor in LARC patients treated with preoperative CRT followed by TME. It may be a better independent staging method than the number of metastatic LNs when <12 LNs are harvested after preoperative CRT.

Lymph node ratio is an independent prognostic factor for rectal cancer after neoadjuvant therapy: A meta‐analysis

“…The remaining 21 studies were reviewed with full texts, among which two studies had unclear reporting of neoadjuvant therapy, one lacked endpoint data, and five lacked comparison between LNR groups. Finally, 13 studies with 4023 participants were included in the meta‐analysis, and all were published in recent years (from 2011 up to now). Table offers the baseline characteristics of all included studies.…”

“…OS, as the primary outcome, was extracted from 11 studies with available data. Among them, eight studies reported high and low LNRs with one cut‐off value, and a pooled HR of 2.94 (95% CI:1.97 to 3.91, P < 0.001) demonstrated that a high LNR is a predictor of poor OS in rectal cancer after neoadjuvant therapy (Figure ). Minor heterogeneity (I 2 < 0.0%, P = 0.949) was found, and a fixed‐effects model was used.…”

“…OS, as the primary outcome, was extracted from 11 studies 25,26,[28][29][30][31][32][33][35][36][37] with available data. Among them, eight studies 25,26,29,32,33,[35][36][37] was found, and a fixed-effects model was used. The other three studies 28,30,31 reported two cut-off values dividing the participants into low, medium, and high LNR groups, and the studies showed that medium and high LNRs were related to poor OS compared with low LNRs (HR:1.31, 95% CI:1.08 to 1.54, P < 0.001; HR:1.68, 95% CI:1.31 to 2.04, P < 0.001, respectively).…”

Prognostic value of pathological node status after neoadjuvant radiotherapy for rectal cancer

“…Kim and colleagues recently demonstrated that ypN status underestimated the risk of future distant metastasis compared with the corresponding pathological nodal category obtained after surgery alone. Studies that evaluated ypN status as a prognostic factor following neoadjuvant radiotherapy have reported contradictory results. In some series ypN category was associated with overall and disease‐free survival, whereas others failed to demonstrate it was an independent factor.…”

“…Studies that evaluated ypN status as a prognostic factor following neoadjuvant radiotherapy have reported contradictory results. In some series ypN category was associated with overall and disease‐free survival, whereas others failed to demonstrate it was an independent factor. Owing to these controversies, some current guidelines recommend basing prognostic evaluation and the decision regarding adjuvant chemotherapy on clinical nodal status (cN) rather than pathological status in patients with rectal cancer treated with neoadjuvant radiotherapy.…”