Patients with stage I (pT1-2 N0 M0) colon cancer (CC) accounts for 15-20% of colonic neoplasia. Stage I CC is mostly cured with surgical resection, consequently, adjuvant chemotherapy is never considered for this subset of patients. Moreover, some international guidelines, including NCCN guidelines, recommend less intensive follow-up 1. However, around 5% of patients with stage I CC will develop a recurrence within 5 years from surgery. Despite the very good prognosis usually attributed to this stage (5-years relapse-free survival: 95%), some clinical and pathological factors beyond the standard AJCC staging may be associated with worse clinical features and may aid in prognostic stratification. Although some authors investigated the role of pathological and clinical factors in patients with stage II and III disease, only few data are available for patients with stage I CC1.

The present multicentric retrospective study aims to:

1. Assess the actual incidence of recurrence in a large cohort of patients with stage I CC undergone curative resection.
2. Investigate the clinical and pathological characteristics of patients who developed a recurrence, with the aim of identifying those associated with a significantly increased risk.
3. Analyze the pattern of recurrence.
4. Analyze survival after recurrence.

Inclusion Criteria:

• Age ≥ 18 years
• Colon cancer up to recto-sigmoid junction
• Histological diagnosis of adenocarcinoma
• pT1 or pT2 according to AJCC staging system
• Urgent and elective surgery
• Curative resection
• Minimally invasive or open surgery
• Completion surgery included (Surgery for endoscopically resected pT1)

Exclusion Criteria:

• Rectal cancer
• Adenoma with low- or high-grade dysplasia
• Histology other than adenocarcinoma (i.e., lymphoma, neuroendocrine tumor, squamous carcinoma, etc)
• Neo-adjuvant chemotherapy or radiotherapy
• History of tumors other than CC

Patients with stage I colon cancer who underwent curative surgery at the participating centers between January 2010 and December 2019.