Delayed-Onset Organ/Space Surgical Site Infection Worsens Prognosis in High-Risk Stage II and III Colorectal Cancer

Background: It is unclear how early- and delayed-onset organ/space surgical site infections (SSIs) affect the long-term prognosis of patients with colorectal cancer, who are potential candidates for adjuvant chemotherapy. This study aimed to investigate the association between the timing of SSI onset and clinical outcome. Methods: This retrospective, multicenter cohort study evaluated patients who were diagnosed with high-risk stage II or III colorectal cancer and underwent elective surgery between 2010 and 2020. Five-year recurrence-free survival (RFS) was the primary endpoint and was compared between early SSI, delayed SSI (divided based on the median date of SSI onset), and non-SSI groups. Results: A total of 2,065 patients were included. Organ/space SSI was diagnosed in 91 patients (4.4%), with a median onset of 6 days after surgery. The early-onset SSI group had a higher proportion of patients with Clavien–Dindo grade ≥IIIb SSI than the delayed-onset SSI. Patients who received adjuvant chemotherapy (AC) had earlier organ/space SSI onset than those who did not. The adjusted hazard ratio of 5-year RFS in the delayed-onset SSI was 2.58 (95% confidence interval: 1.43–4.65; p = 0.002): higher than that in the early-onset SSI, with the non-SSI as the reference. Conclusions: Delayed-onset organ/space SSI worsened long-term prognosis compared to early-onset, and this may be due to delayed initiation of AC. Patients who are clinically suspected of having lymph node metastasis might need additional intervention to prevent delays in commencing AC due to the delayed SSI.