Clinically Node Negative, Pathologically Node Positive Rectal Cancer Patients Who Did Not Receive Neoadjuvant Therapy

Abstract

Purpose: Neoadjuvant chemoradiotherapy is the preferred standard of care for clinical stages II-III rectal cancer. It is uncertain whether clinically node negative (cN-) tumors found to be pathologically stage III could be optimally treated with surgery alone and avoid adjuvant treatments. The aim of our study was to define the outcomes of such patients.

Methods: Patients undergoing radical surgery using total mesorectal excision (TME) techniques for rectal cancer (≤12 cm from the anal verge) with curative intent during 2000-2012 and found to have stage III disease on final pathology were identified from a prospectively maintained database. Patients were staged with abdominopelvic CT, transrectal endoscopic ultrasound, and/or pelvic MRI. Exclusion criteria were cN+ without neoadjuvant chemoradiotherapy, hereditary colorectal syndromes, inflammatory bowel diseases, lack of preoperative nodal staging, intraoperative radiotherapy, and follow-up <3 years. We compared cN-/pN+ patients according to the postoperative treatment received (group 1 if no further treatment, group 2 if any postoperative treatments), using ypN+ patients (neoadjuvant chemoradiotherapy + surgery) as controls (group 3). Oncological outcomes evaluated included overall survival (OS), disease-specific survival (DSS), disease-free survival (DFS), local recurrence (LR), and distant recurrence (DR).

Results: Out of 218 patients included in the study, 77 cN- patients underwent initial surgery with a pN+ surgical specimen. Eighteen of these patients received no postoperative treatment due to associated comorbidity, patient preference, or postoperative complications while the remaining 59 (group 2) patients received chemoradiotherapy (n = 21) or chemotherapy alone (n = 38), respectively, and group 3 included 141 patients. Distal, radial resection margins and TME grading when available were comparable among groups. cN-/pN+ patients treated with surgery alone were associated with significantly poorer cancer outcomes compared with cN-/pN+ patients who received any form of adjuvant therapy and to ypN+ patients.

Conclusion: TME surgery is not sufficient to optimize outcomes among rectal cancer patients believed to be node negative and found to be stage III based on specimen pathology.

Keywords: Adjuvant therapy; Chemotherapy; Radiotherapy; Rectal cancer; Rectal cancer imaging; Surgery.