['The impact of lymph node (LN) dissection on long-term outcomes for patients with colorectal cancer (CRC) perforation remains unclear. We aim to investigate factors associated with poor prognosis and recurrence in patients with CRC, with special reference to cancer perforation and LN dissection.', 'The subjects comprised 550 patients who underwent colorectal surgery for CRC at Stage II or III (TNM classification) between February 2006 and November 2013. Short- and long-term outcomes of patients with or without CRC perforation were evaluated. We also sought risk factors on poor prognosis, focusing on LN dissection in patients with CRC perforation.', 'A total of 508 underwent surgery for CRC without perforation (the non-perforation group) and 39 for CRC with perforation (the perforation group). Both overall survival and recurrence-free survival rates were significantly lower in the perforation group than in the non-perforation group (overall survival, P\xa0=\xa00.009; recurrence-free survival, P\xa0<\xa00.001). The relapse rates at the peritoneum (P\xa0=\xa00.002), lung (P\xa0=\xa00.007) and LNs (P\xa0=\xa00.021) were significantly higher in the perforation group than in the non-perforation group. Multivariable Cox proportional hazards model revealed that CRC perforation (hazard ratio [HR] 2.55, 95\xa0% confidential interval [CI] 1.16-4.98, P\xa0=\xa00.022), LN dissection <12 (HR 1.83, 95\xa0% CI 1.07-3.13, P\xa0=\xa00.027), and Stage III (HR 1.79, 95\xa0% CI 1.06-3.08, P\xa0=\xa00.031) were significant and independent risk factors for poor prognosis.'] Is insufficient Lymph Node Sampling in Patients with Colorectal Cancer Perforation Associated with an Adverse Oncological Outcome?