Revealing Connection Between BMI and Right-Colon Cancer

A study by researchers at Cleveland Clinic in Florida identified a linear increase in advanced nodal disease linked to increased body mass index (BMI) for patients with right-colon cancer. This interesting finding could have implications for the assessment and treatment of patients with obesity diagnosed with colon cancer, according to lead author Sameh H. Emile Rizkalla, MBBCh, MSc, MD, FACS, a senior researcher based at Cleveland Clinic Weston Hospital.

“As reported in the literature, patients with an increased BMI can be more challenging to laparoscopically treat, resulting in longer operation times and higher rates of conversion to open surgery,” says Dr. Rizkalla. “We wanted to look more closely at how BMI impacts outcomes for patients undergoing right hemicolectomy, especially since the majority of the patients we currently treat are outside the normal range for BMI, and the incidence of obesity is continuing to rise nationally.”

Obesity is a known environmental risk factor for colorectal cancer and an increasing problem in the United States, where approximately 42% of adults have obesity, according to National Health and Nutrition Examination Survey data.

Study methodology

The retrospective cohort study, accepted for poster presentation at this year’s Annual Scientific Meeting of the American Society of Colon & Rectal Surgeons, included 270 patients who underwent right hemicolectomy for cancer or irretrievable polyps at Cleveland Clinic Florida between 2011 and 2021. The colon resections were performed laparoscopically and entailed removing the ascending colon and part of the transverse colon, along with fat and lymph nodes.

Patients were stratified into five BMI groups following WHO classification criteria: normal BMI (18-24.9 kg/m2), overweight (25 to <30 kg/m2), class I obesity (30 to <35 kg/m2), class II obesity (35 to <40 kg/m2), and class III obesity (≥40 kg/m2). Outcome measures included operation time, hospital stay, complications, reoperation, number of harvested and positive lymph nodes, resection status, and tumor recurrence.

Key findings

As anticipated, the Cleveland Clinic researchers found that the mean operation time was significantly longer in patients with class II-III and class I obesity than in patients with normal BMI (197.1 and 160 vs 143.3 minutes, p=0.004). However, there were no significant differences among the BMI groups in estimated blood loss, hospital stay, complications, mortality, reoperation, tumor recurrence, and survival.

“What was much more surprising was the linear increase in advanced nodal disease in proportion to BMI,” says Dr. Rizkalla. “This was a revealing pattern that has not previously been reported.”

The proportion of N2 stage, denoting advanced nodal disease, increased from 3.9% in patients with normal BMI to 6.4% in overweight patients, then to 12.5% in patients with class I obesity, and finally to 16.7% in class II-III obesity; this linear trend was statistically significant (p=0.024).

“We also observed that patients with an increased BMI were younger, tend to be more often male, and had diabetes mellitus more often than did patients with normal BMI or who were overweight,” he adds.

Impact on clinical care

Dr. Rizkalla notes that their findings concur with other reports supporting the safe use of minimally invasive hemicolectomy for patients with obesity.

Meanwhile, the greater risk of advanced nodal disease in patients with class II-III obesity may prompt surgeons to consider additional pre-operative assessments and adjusting treatment approaches for certain patients to include more extensive lymphadenectomies and potential use of complete mesocolic excision (CME). The latter is an extended resection used to remove the tumor and its entire adjacent mesentery intact, including mesentery blood vessels, lymphatic vessels, and lymph nodes through which tumor cells may spread.

“While CME is a more complex procedure, this extensive surgical approach may help remove affected nodal tissue and reduce cancer recurrence,” explains Dr. Rizkalla. “Unfortunately, because it’s a more technically demanding, longer procedure than a standard mesocolic excision, its performance in patients with elevated BMI raises concerns of further increases in operative times and morbidity.”

Future research

Because this investigation is a single-center, retrospective study with a relatively small number of patients, Dr. Rizkalla says the linear relationship between BMI and advanced nodal disease merits further research as does its treatment implications. “There are a lot of unanswered questions about the relationship between obesity and colon cancer, including the molecular mechanism at work,” he says.

Dr. Rizkalla also points to the need for better pre-operative imaging techniques and protocols that factor in BMI. “Assessing nodal disease prior to colon resection remains challenging despite improved MRI technology and the use of PET-CT scan imaging,” he adds.