This study aims to elucidate whether there is a difference in long-term prognosis between laparoscopic surgery and open surgery in colon cancer patients with visceral obesity.

Study on Surgical Approaches for Colon Cancer Patients with Visceral Obesity

Colorectal cancer stands as a major malignant tumor threatening human health. Laparoscopic surgery has been widely adopted in colon cancer treatment, as it yields comparable survival outcomes to open surgery while offering the advantage of minimal invasiveness. However, with the global escalation of obesity, laparoscopic intervention becomes increasingly challenging in colon cancer patients with visceral obesity, potentially compromising surgical quality.

Notably, earlier landmark studies including COST, COLOR, and CLASICC have confirmed that laparoscopic surgery is non-inferior to open surgery in colon cancer patients. Nevertheless, these studies enrolled relatively lean patients with a Body Mass Index (BMI) below the average level of their respective regions; the COLOR study even excluded patients with a BMI exceeding 30 kg/m². Additionally, transverse colon cancer and splenic flexure colon cancer were excluded from these trials, rendering their data insufficiently representative of the growing population of obese colon cancer patients.

In contrast, the JCOG0404 study specifically demonstrated that colon cancer patients with a BMI ≥ 25 kg/m² had significantly poorer prognostic outcomes after laparoscopic surgery compared to open surgery. Further evidence from European waist-to-hip ratio studies and meta-analyses indicates that obese patients-especially those with abdominal obesity-pose greater surgical challenges. For such patients, laparoscopic surgery is associated with fewer harvested lymph nodes, higher conversion rates to open surgery, and potentially compromised surgical quality, which may ultimately lead to inferior long-term prognosis.

The Body Round Index (BRI), calculated using height and waist circumference, serves as a robust predictor of Visceral Fat Area (VFA). It exhibits superior performance to traditional anthropometric indicators such as BMI, waist circumference, and waist-to-hip ratio. Based on BRI and BMI data from Chinese and American populations, as well as clinical observations by the research team, patients with a BRI ≥ 5.0 present with significant visceral fat accumulation, which substantially increases the complexity of surgical procedures.

This study is designed as a prospective, international, multicenter, randomized, open-label, parallel-controlled trial to clarify whether open surgery is superior to laparoscopic surgery in terms of long-term outcomes for colon cancer patients with visceral obesity (defined as BRI ≥ 5.0). Eligible participants meeting all inclusion criteria will be enrolled and randomly assigned in a 1:1 ratio to either the laparoscopic surgery group or the open surgery group. Both groups will undergo surgery adhering to the Complete Mesocolic Excision (CME) standard. Postoperatively, patients will be followed up for 5 years in accordance with the predefined follow-up protocol. The primary outcome measure is the 3-year disease-free survival rate, while secondary outcomes include specimen quality, 30-day postoperative complications and mortality.

Inclusion Criteria:

1. Body Roundness Index (BRI) ≥ 5.0, with no laparoscopic surgery contraindications as assessed by the surgeon;
2. Pathologically confirmed colon adenocarcinoma, mucinous adenocarcinoma, or signet ring cell carcinoma;
3. Tumor lower edge > 12 cm from the anus as measured by colonoscopy, and the tumor lower edge not directly palpable by digital rectal examination;
4. Single primary lesion;
5. Aged 18 (inclusive) to 75 (inclusive) years;
6. Clinical stage T3/4Nany or T1-4N+ on chest non-contrast CT and abdominal enhanced CT, no distant metastasis, and resectable as judged by the surgeon;
7. Treatment-naive, no prior anti-tumor treatment;
8. Completed blood routine, liver and kidney function tests, carcinoembryonic antigen (CEA), and carbohydrate antigen 199 (CA199) before randomization, with American Society of Anesthesiologists (ASA) score ≤ III;
9. Patient able to understand the study protocol and willing to participate in the study.

Exclusion Criteria:

1. Height and waist circumference data are unavailable;
2. Hereditary colorectal cancer (Lynch syndrome or Familial Adenomatous Polyposis [FAP]);
3. History of previous malignant neoplasm, with the exception of basal cell carcinoma/papillary thyroid carcinoma/various types of in situ cancers/micro-invasive early-stage lung cancer;
4. Acute exacerbation of major organ diseases (such as, but not limited to, COPD, coronary heart disease, and renal insufficiency) and/or severe acute infectious diseases (such as, but not limited to, hepatitis, pneumonia, and myocarditis);
5. The tumor presents with obstruction or is at high risk of obstruction, and/or there is bleeding and/or perforation, which may necessitate emergency surgery;
6. Pregnancy or breastfeeding;
7. Inability to undergo contrast-enhanced CT scan;
8. Additional surgery after EMR or ESD;
9. Patients with unremitted severe mental illness, moderate or above cognitive impairment (MMSE ≤ 23 points), or those who have been hospitalized due to mood disorders in the past year or have unstable antipsychotic medication;
10. Patients with enlarged mesenteric root lymph nodes detected by preoperative CT or intraoperative exploration and suspected metastasis, or suspected metastasis in organs such as peritoneum or liver detected by intraoperative exploration;
11. Patients with a history of major abdominal surgery and severe adhesions precluding laparoscopic surgery upon laparoscopic exploration.

In accordance with the requirements of the International Committee of Medical Journal Editors, the de-identified raw data of this study will be made public after the results are published. The access method will be stated when the research results are published.

The access method will be stated when the research results are published.

To access the Individual Participant Data (IPD), a detailed data usage plan must be submitted, specifying the research objectives and study content, which will be approved following review by the Principal Investigator (PI) of this study.