Abstract
Postoperative adjuvant chemotherapy for patients with stage III colon cancer (CC) is regarded as the standard treatment worldwide for outcome improvement and relapse prevention. Similarly, high-risk stage II CC requires adjuvant chemotherapy because of its high recurrence rate. Previous randomized controlled trials showed that oxaliplatin (OX), in addition to fluorinated pyrimidine-based therapy for patients with stage II/III CC, significantly improves cancer survival but it remains controversial as to which patient groups should receive OX-containing regimens. Among 1,150 consecutive patients who underwent curative resection for stage II/III CC between 2009 and 2016 at two tertiary hospitals, 349 patients treated with only peroral (PO) fluorinated pyrimidine-based chemotherapy and 149 patients who received fluorinated pyrimidine-based chemotherapy with OX as adjuvant chemotherapy were retrospectively reviewed. The primary outcome was recurrence-free survival (RFS). Clinicopathological factors were more advanced in patients treated with OX than in patients treated only with PO fluorinated pyrimidine agents. Multivariate analysis for 5-year RFS showed that T4 [hazard ratio (HR), 2.947; P=0.0001], N2 (HR, 2.704; P=0.0075), vessel or lymphatic invasion (HR, 1.675; P=0.0437) and high cancer antigen (CA)19-9 (HR 3.367, P=0.0002) levels were independent risk factors of cancer relapse. Propensity score matching analysis was performed to match clinicopathological differences between the PO and OX groups. After matching, subgroup analysis of the patients showed that greater effects of OX on cancer survival were observed in patients in the OX group with high CA19-9 levels and tended to be associated with T4 and N2 compared with the PO group. Thus, OX-containing regimens should be recommended for patients with CC with these factors in an adjuvant setting.
Highlights
Colon cancer (CC) is the third highest cause of cancer‐asso‐ ciated mortality in the United States [1]
A total of 564 patients received no postoperative adjuvant chemotherapy, 149 patients were treated with OX‐containing regimens and 349 patients were treated with PO fluorinated pyrimidine agent
In Japan, postoperative adjuvant chemotherapy following R0 resection is recommended for patients with high‐risk stage II or III colorectal cancer (CRC) by the Japanese Society for Cancer of the Colon and Rectum (JSCCR) guidelines 2019
Summary
Colon cancer (CC) is the third highest cause of cancer‐asso‐ ciated mortality in the United States [1]. In Japan, CC is the leading cause of mortality in women and the third highest cause in men. Surgery is the most suitable treatment for patients with resectable CC and the number of laparoscopic surgeries performed in Japan is increasing [3]. In advanced CC with distant metastases, prolonged survival be achieved by multidisciplinary therapy such as surgery, chemotherapy, immunotherapy and radiation, but patients still have a poor prognosis; the 5‐year overall survival rate is 16.7% in Japan [4]. Because recurrent CC has a poor prognosis, recurrence prevention contributes to extending survival. Postoperative adjuvant chemotherapy aims to decrease recurrence in patients with stage II/III disease following R0 surgery
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