Association of Lateral Pelvic Lymph Nodes with Disease Recurrence and Organ Preservation in Patients with Distal Rectal Adenocarcinoma Treated with Total Neoadjuvant Therapy.

Abstract

To assess the significance of enlarged lateral lymph nodes (LLN) for disease recurrence, metastasis, and organ preservation in patients with rectal cancer. Optimal treatment of rectal adenocarcinoma involving LLN is subject to debate. A post hoc analysis of the Organ Preservation in Rectal Adenocarcinoma trial, a multicenter study of patients with rectal cancer treated with total neoadjuvant therapy (TNT) followed by total mesorectal excision or watch-and-wait management. We analyzed the association of visible LLN (LLN+), LLN ≥7 mm (short axis) on baseline magnetic resonance imaging (MRI), and LLN ≥4 mm on restaging MRI with recurrence, metastasis, and rectum preservation. At baseline, 57 out of 324 (18%) patients had LLN+. In 30 (53%) of 57 patients with LLN+ on baseline MRI, the LLN disappeared after TNT. Disease recurrence in LLN was rare (3.5% of patients with LLN+ and 0.4% of patients with LLN-). All patients with recurrence in LLN also had distant metastasis. The rate of organ preservation was significantly lower in patients with LLN ≥4 mm on restaging MRI ( P = 0.013). We found no significant differences in rates of local recurrence or metastasis between patients with LLN+ versus LLN- and in patients with LLN ≥7 versus <7 mm on baseline MRI. LLN dissection was performed in 3 patients; 2 of them died of distant metastasis. LLN involvement is not associated with disease recurrence or metastasis, but persistence of LLN ≥4 mm after TNT is negatively associated with rectum preservation in patients with locally advanced rectal cancer treated with TNT. Dissection of lateral nodes likely benefits few patients.