Underweight as a Risk Factor for Major Intra-abdominal Malignancy Surgeries

Purpose The relationship between body mass index (BMI) and postoperative outcomes for oncology surgeries among the Asian population remains controversial. A prevailing perception suggests that excess adiposity is associated with reduced cancer survival. However, several reports have shown that overweight or early obese states confer better survival outcomes. It is hypothesized that patients with better nutrition and surplus calories grant survival advantages to radical cancer treatment. The purpose of this study is to examine the relationship between BMI and postoperative 30-day and one-year mortality in the Asian population. Methods This retrospective review investigates the postoperative mortality, intensive care unit (ICU) admission, and length of hospital stay following major abdominal cancer surgeries within the Asian population. Patients were stratified into three groups based on their BMI: underweight (BMI < 18.5 kg/m²), normal weight (BMI 18.5-27.5 kg/m²), and obese (BMI > 27.5 kg/m²). Results A total of 646 patients were included in this study. At 30 days, the underweight group presents an 8% mortality compared to 1% and 3% mortality in the normal BMI and obese groups, respectively. At one year, the low BMI group presents a significant increase in mortality of 53% as opposed to the normal BMI and obese group with mortality rates of 14% and 12%, respectively (p < 0.001). There is a significant increase in the ICU admission rate in the underweight group (n = 13, 25%) compared to the normal BMI and obese groups (n = 26, 6%; n = 8, 6% p < 0.001). Similarly, the group with lower BMI was observed to require a longer hospital stay postoperatively (median (IQR) 11.0 (4.0-24.0)) compared to the normal (median (IQR) 4.0 (3.0-9.0)) and obese (median (IQR) 4.5 (3.0-8.0)) patients. Conclusion Concordant results were observed in the underweight patient group with increased one-year mortality, ICU admission rate, and hospital stay postoperatively. Low BMI presents as an independent risk factor for major radical surgeries.