Recurrent Rate in Rectal Cancer Patients with Clinically Suspected Lateral Pelvic Lymph Node Metastasis Following Neoadjuvant Chemoradiotherapy (CRT) and Total Mesorectal Excision (TME)

Background: The presence of lateral pelvic lymph node (LPLN) metastasis in rectal cancer has been associated with poor prognosis. We aimed to determine the recurrent outcome in patients with clinically suspected LPLN metastasis following neoadjuvant chemoradiotherapy (CRT) and total mesorectal excision (TME) Materials and Methods: Rectal cancer patients who received neoadjuvant chemoradiotherapy (CRT) and total mesorectal excision (TME) between 2014 and 2023. The Patients’ characteristics, LPLNs status, MRI or CT findings, operative and pathologic findings, recurrent rate, and survival rate were analyzed retrospectively. Results: Among 131 patients, 88 were in the non-suspected group and 43 in the suspected group before CRT. After CRT, 86 patients in the non-suspected group remained non-suspected, while 2 developed newly suspected LPLN. In the suspected group, 15 patients responded to CRT, whereas 28 remained persistently suspected. The overall recurrence rate was 27.5% (36/131), including 4.6% (6/131) locoregional, 15.3% (20/131) distant, and 7.6% (10/131) both locoregional and distant recurrence. The newly suspected group had significantly worse recurrence outcomes than the non-suspected group (HR = 8.95, 95% CI: 2.02–39.63; p = 0.004). However, there were no significant differences in recurrence rates for the responded group (HR = 1.11, p = 0.865) and persistently suspected group (HR = 1.23, p = 0.607) compared to the non-suspected group. Post-treatment analysis revealed that LPLN location in the obturator region and unilateral involvement were significantly associated with increased locoregional recurrence risk. However, only 1 out of 16 patients with local recurrence developed lateral local recurrence. Conclusion: Neoadjuvant chemoradiotherapy provided comparable local disease control between patients with and without clinically suspected LPLN metastasis in rectal cancer. The progression of LPLNs after CRT was a significant risk factor for recurrence compared to non-progression, highlighting the importance of post-treatment imaging in predicting oncologic outcomes.