Oncologic Outcomes according to the Treatment Strategy in Radiologic Complete Responders after Neoadjuvant Chemoradiation for Rectal Cancer.

OBJECTIVE: This study aimed to compare the oncologic outcomes between treatment strategies for rectal cancer [radical surgery, local excision (LE), and the wait-and-see approach] in radiologic complete responders after neoadjuvant chemoradiation (nCRT).

METHODS: We retrospectively reviewed rectal cancer patients and included 52 radiologic complete responders after nCRT defined as no residual tumor or residual fibrosis and no suspicious metastatic lymph nodes on magnetic resonance imaging (MRI). Clinicopathologic features and oncologic outcomes were compared according to the treatment strategies.

RESULTS: The median follow-up period was 41 months (range, 6-80). Twenty-eight patients underwent radical surgery, whereas 16 underwent LE, and 8 were closely monitored without initial surgery. The pathologic complete response rate was 40.9%. Patients who underwent radical surgery showed better prognosis compared to those who underwent LE or wait-and-see (3-year disease-free survival: radical surgery 85.0% vs. LE 62.5%, wait-and-see 75.0%, p = 0.019; 3-year local recurrence-free survival: radical surgery 96.4% vs. LE 67.0%, wait-and-see 75.0%, p = 0.009). After recurrence, patients who underwent salvage surgery showed a relatively good oncologic outcome.

CONCLUSION: Pursuing LE or the wait-and-see approach instead of radical surgery in rectal cancer patients undergoing nCRT may bring about a detrimental oncologic outcome if clinical complete response is solely determined by MRI.