Impact of adjuvant chemotherapy completion on oncologic outcomes in YPTNMStage 2 rectal cancer patients

Purpose: Adjuvant chemotherapy (aCT) in rectal cancer patients who have undergone curative resection after neoadjuvant chemoradiation (nCRT) is controversial. We aimed to investigate the benefits of using aCT and the clinical impact of completing aCT in ypstage 2 rectal cancer patients. Methods: We retrospectively reviewed clinicopathological data from patients who had undergone radical resection after nCRT between January 2006 and December 2012. In total, 152 patients with ypT3/4N0M0 rectal cancer were included. Of these patients, 139 initiated aCT, while 13 did not receive aCT (no-aCT). Among those who received aCT, 132 patients completed their planned cycles (aCT-completion) whereas 7 did not (aCT-incompletion). All patients received long-course chemoradiation; a 5-fluorouracil-based regimen was used for nCRT in most patients. The prognostic factors affecting disease-free survival (DFS) and overall survival (OS) were analyzed. Results: The median follow-up duration was 41 months. Demographic data did not differ significantly among the 3 groups. In multivariate analysis, open surgery, a tumor size >2 cm, retrieval of <12 lymph nodes, circumferential resection margin (CRM) positivity and aCT incompletion were independent prognostic factors for poor DFS. Old age (≥60 years), open surgery, CRM positivity, aCT incompletion, and lack of aCT initiation compared to aCT completion were independent prognostic factors for poor OS. Conclusion: In ypstage 2 rectal cancer patients, aCT after nCRT and total mesorectal excision affected both DFS and OS; however, only patients who completed planned aCT exhibited survival benefits. Therefore, improving patients' compliance with the completion of aCT is desirable.