CROSCO-1 study is a national, multi-center, prospective observational study presenting patients to the emergency departments of the participating centers with obstructive left colon cancer (in the absence of metastases and peritoneal carcinomatosis) undergoing primary surgical tumor resection with a primary colorectal anastomosis (associated or not with a diverting loop ileostomy) or without a primary anastomosis ("Hartmann's procedure") or staged resection after endoscopic stenting with Self-expandable Metallic Stent (SEMS).

The main questions it aims to answer are:

• the Stoma rate at 1 year after tumor resection
• the 30-day and 90-day major morbidity and mortality
• 1-year quality of life (EQ-5D-5L test)
• Timing of chemotherapy initiation and type of chemotherapy regimen. Participants will have an obstructive left colon cancer localized (no peritoneal carcinosis or distant metastasis).

Researchers will compare: primary surgical tumor resection with a primary colorectal anastomosis (associated or not with a diverting loop ileostomy) or an "Hartmann's procedure" with a staged resection after endoscopic stenting with SEMS.

Since surgical and oncological outcomes of the different treatment strategies for obstructing left colon cancers have not been studied on a large scale globally, we launched the CROSCO-1 study intending to compare the clinical results of all these therapeutic regimens in a cohort of patients treated for obstructive left-sided colorectal cancer (CRC).

The primary aim of the CROSCO-1 (Colonic Resection, stOma or self-expanding metal Stents for obstruCtive left cOlon cancer) study is to describe the outcomes of the management of emergency presentations of obstructive left CRC with colorectal resection with or without primary anastomosis versus the staged approach with SEMS insertion and subsequent colorectal resection. The primary aim of the CROSCO-1 study will be the 1-year stoma rate of patients undergoing primary emergency surgical resection (Hartmann procedure or primary resection and anastomosis) compared with patients undergoing staged resection (emergency endoscopic treatment with SEMS followed by elective resection). Other outcomes will be 30-day and 90-day major morbidity and mortality, 1-year quality of life, and the timing and type of chemotherapy initiation in the two groups.

Inclusion Criteria:

1. Patients of both sexes, ≥ 18 years old.
2. Patients with abdominal CT scan diagnosis of colonic obstruction due to obstructive left colonic cancer (sigmoid or descending colon).
3. Absence of distant metastases on abdominal and chest CT scan.
4. Patients who may face a one-year follow-up.
5. Patients fit for surgery.
6. Patients with colonic adenocarcinoma on postoperative histological examination.

Exclusion Criteria:

1. Right-side or trasverse colon cancer.
2. Surgical or endoscopic palliation in patients with peritoneal carcinomatosis, locally advanced Colorectal cancer (CRC) (T4 sec. TNM), M1 disease.
3. Bowel obstruction determinated by other tumors or benign inflammatory stenosis.
4. Concomitant bowel abscess, perforation, or fistula.
5. Elective procedures.
6. Pregnancy or lactation.

The study population includes all consecutive adult patients (≥18 years of age) presenting acutely ( unplanned and non-elective presentation to hospital for urgent or emergency reasons) at the participating centers with a clinical and radiological diagnosis of (known or unknown descending or sigmoid colon tumor) for 1 year. According to the different management methods, the cohort will be divided into the following categories:

1. Primary tumor resection, which will include patients treated with Hartmann's procedure or primary resection with anastomosis (with or without a diverting ileostomy).
2. Staged tumor resection, which will include patients treated with a Self-expandable Metallic Stent (SEMS) insertion, followed by colorectal resection.

all individual participant data (IPD) that underlie results in a publication

IPD can be Share for 1 year after follow up closure

by email with colleagues who will be interested