The Role of Adjuvant Chemotherapy in ypT0N0 Rectal Adenocarcinoma

Background: In patients who develop a complete pathologic response (ypT0N0) following neoadjuvant chemoradiation, the benefits of postoperative chemotherapy remain uncertain. This study aims to determine whether treatment with adjuvant chemotherapy in ypT0N0 patients affects short- and long-term outcomes. Methods: From January 2000 to December 2015, 992 patients at our institution underwent surgery for rectal adenocarcinoma following treatment with neoadjuvant chemoradiation. A complete pathologic response was noted in 96 (9.7%) patients. Adjuvant chemotherapy was administered to 60 (62.5%) patients. We reviewed clinical and pathological records and compared outcomes in ypT0N0 patients who received adjuvant chemotherapy to those who did not. Results: The mean age of patients who received adjuvant chemotherapy was 55.6 ± 11.5 years, compared to 62.1 ± 11.7 years for those who did not (p = 0.008). Among the two groups, mean follow-up time after surgery was 5.3 ± 4.1 years for the adjuvant group and 8.3 ± 5.5 years for the non-adjuvant cohort (p = 0.003). The 1, 3, and 5-year survival rates were 100.0%, 97.7%, and 92.1% for patients who received adjuvant chemotherapy and 97.2%, 94.1%, and 90.7% for those who did not (p = 0.382). In a subanalysis of patients with available follow-up information, we observed 3/53 (5.7%) disease recurrences in patients who received adjuvant chemotherapy, compared to 2/18 (11.1%) in those who were not treated postoperatively (p = 0.456). Conclusion: In patients with ypT0N0 rectal adenocarcinoma, we found equivalent survival and recurrence outcomes. Further study will be necessary to determine the importance of adjuvant chemotherapy following ypT0N0 resection.