The impact of lymph node harvest on recurrence in rectal cancer after neoadjuvant chemoradiotherapy.

BACKGROUND

Although current guidelines recommend harvesting ≥12 lymph nodes (LNs) for rectal cancer staging, its appropriateness after neoadjuvant chemoradiotherapy (nCRT) remains debated. This study evaluated the prognostic value of harvested LNs (HLNs) after nCRT.

METHODS

We retrospectively analyzed 1596 patients who underwent radical surgery for rectal cancer after nCRT at 2 tertiary hospitals between April 2004 and December 2021. Patients were categorized by the number of HLNs (≥12 vs <12). Clinicopathologic outcomes and recurrence were compared, and multivariable analyses were performed to identify factors associated with recurrence and survival.

RESULTS

Less than 12 HLNs were found in 321 patients (20.1%), and ≥12 in 1275 (79.9%). No significant differences were observed in age, sex, tumor height, resection margins, or circumferential resection margin involvement. The ≥12 HLNs group showed more advanced ypT, ypN, and overall stage, with higher rates of venous and perineural invasion. Completeness of postoperative chemotherapy was comparable. However, the <12 HLNs group demonstrated a higher recurrence rate (24.6% vs 18.8%; P = .026). In multivariate analysis, <12 HLNs were identified as independent risk factors for overall survival (OS) (hazard ratio [HR], 1.624; P = .002) and disease-free survival (HR, 1.297; P = .047). Kaplan-Meier analysis showed 5-year OS was significantly lower in the <12 HLNs group than the ≥12 HLNs group (83.1% vs 86.1%; P = .003).

CONCLUSION

Harvesting fewer than 12 LNs was significantly associated with worse OS and remains an independent prognostic factor of rectal cancer after nCRT.