Downstaged lateral pelvic lymph nodes require no resection after neoadjuvant therapy and total mesorectal excision.

BACKGROUND

This study evaluated lateral lymph node (LLN) downstaging on restaging magnetic resonance imaging (MRI) and its impact on local recurrence (LR) in patients with stage 3 rectal cancer undergoing neoadjuvant therapy followed by curative surgery.

METHODS

This was a retrospective review of adult patients with stage 3 rectal cancer who underwent neoadjuvant therapy followed by curative surgery between 2014 and 2023 at a high-volume center. Patients were divided into 2 groups based on LLN status: patients with negative LLN on baseline MRI (group 1) and patients with positive LLN on baseline MRI, which downstaged to negative on restaging MRI (group 2).

RESULTS

A total of 397 patients (group 1, 310; group 2, 87) underwent curative surgery for locally advanced rectal cancer. There were no significant differences between both groups regarding age, sex, body mass index, mesorectal fascia involvement, and clinical T stage. However, a significantly lower proportion of group 1 patients received total neoadjuvant therapy as neoadjuvant treatment than group 2 patients (43.5% vs 62.1%; P =.002). Group 2 had a significantly higher proportion of LLN dissection (LLND) (2.9% vs 17.2%; P <.001). However, all the surgically removed LLNs were negative for tumors. At 5-year follow-up, Kaplan-Meier curves demonstrated that there was no significant difference between both groups in LR rate (2.3% vs 4.6%; P =.21), LLN recurrence rate (0.6% vs 1.1%; P =.61), and disease-free survival (83.9% vs 86.2%; P =.61).

CONCLUSION

Observation rather than LLND may be appropriate for patients with downstaged LLNs based on restaging MRI findings after neoadjuvant therapy.