Lean body mass index is a marker of advanced tumor features in patients with hepatocellular carcinoma

Obesity is an independent risk factor for the development of hepatocellular carcinoma (HCC) and may influence its outcomes. However, after diagnosis of HCC, like other malignancies, the obesity paradox may exist where higher body mass index (BMI) may in fact confer a survival benefit. This is frequently observed in patients with advanced HCC and cirrhosis, who often present late with advanced tumor features and cancer related weight loss.

To explore the relationship between BMI and survival in patients with cirrhosis and HCC.

This is a retrospective cohort study of over 2500 patients diagnosed with HCC between 2009-2019 at two United States academic medical centers. Patient and tumor characteristics were extracted manually from medical records of each institutions' cancer registries. Patients were stratified according to BMI classes: < 25 kg/m² (lean), 25-29.9 kg/m² (overweight), and > 30 kg/m² (obese). Patient and tumor characteristics were compared according to BMI classification. We performed an overall survival analysis using Kaplan Meier by the three BMI classes and after adjusting for Milan criteria. A multivariable Cox regression model was then used to assess known risk factors for survival in patients with cirrhosis and HCC.

A total of 2548 patients with HCC were included in the analysis of which 11.2% (n = 286) were classified as non-cirrhotic. The three main BMI categories: Lean (n = 754), overweight (n = 861), and obese (n = 933) represented 29.6%, 33.8%, and 36.6% of the total population overall. Within each BMI class, the non-cirrhotic patients accounted for 15% (n = 100), 12% (n = 94), and 11% (n = 92), respectively. Underweight patients with a BMI < 18.5 kg/m² (n = 52) were included in the lean cohort. Of the obese cohort, 42% (n = 396) had a BMI ≥ 35 kg/m². Out of 2262 patients with cirrhosis and HCC, 654 (29%) were lean, 767 (34%) were overweight, and 841 (37%) were obese. The three BMI classes did not differ by age, MELD, or Child-Pugh class. Chronic hepatitis C was the dominant etiology in lean compared to the overweight and obese patients (71%, 62%, 49%, P < 0.001). Lean patients had significantly larger tumors compared to the other two BMI classes (5.1 vs 4.2 vs 4.2 cm, P < 0.001), were more likely outside Milan (56% vs 48% vs 47%, P < 0.001), and less likely to undergo transplantation (9% vs 18% vs 18%, P < 0.001). While both tumor size (P < 0.0001) and elevated alpha fetoprotein (P < 0.0001) were associated with worse survival by regression analysis, lean BMI was not (P = 0.36).

Lean patients with cirrhosis and HCC present with larger tumors and are more often outside Milan criteria, reflecting cancer related cachexia from delayed diagnosis. Access to care for hepatitis C virus therapy and liver transplantation confer a survival benefit, but not overweight or obese BMI classifications.