pT1 colorectal cancer (CRC) is defined by invasion limited to the submucosa without extension beyond it. With the widespread implementation of colorectal cancer screening programs, its incidence has markedly increased.

The aim is to describe our experience in the diagnosis and management of pT1 colorectal cancer.

We conducted a retrospective review of all pT1 CRC cases diagnosed and managed at a tertiary center between January 2021 and December 2024. Demographic, endoscopic, histologic, and therapeutic data were collected.

A total of 92 patients were included, with a mean age of 64 years; 58.7% were men. The main indications for colonoscopy were colorectal cancer screening (58%), diarrhea (10.9%), rectal bleeding (9.8%), and iron-deficiency anemia (6.5%). Most lesions (91%) were resected endoscopically, while the remaining cases underwent surgical resection due to suspected submucosal invasion. The rectum was the most frequent location (43%).

Computed tomography excluded nodal or distant metastases in all cases.

Among patients treated endoscopically, 39.3% met histologic criteria for low-risk lesions (submucosal invasion <1 mm, resection margins >1 mm, absence of lymphovascular invasion, low/intermediate tumor budding, and well/moderate differentiation). Of these, 87.9% were managed by endoscopic follow-up, while 12.1% underwent surgery based on patient preference.

In contrast, among of the cases fulfilled high-risk criteria (58.3%); 65.3% were managed conservatively due to significant comorbidities or patient choice. The most common reason for high-risk classification was piecemeal resection, precluding accurate histological assessment (24.5% as the sole criterion), followed by positive margins and lymphovascular invasion.

During follow-up, no local or nodal recurrences were observed.

Accurate endoscopic recognition of lesions with suspected submucosal invasion and in bloc resection are essential to guide optimal management in pT1 colorectal cancer. Although no recurrences were detected in our cohort, long-term surveillance remains necessary to assess oncologic outcomes and validate the safety of conservative management strategies in selected cases.