What Emerging CT Research Reveals About Obesity and Post-Op Survival for Non-Small Cell Lung Cancer

In a new study involving over 7,000 patients who underwent curative resection for non-small cell lung cancer (NSCLC), obese patients with no evidence of low skeletal muscle mass (LSMM) or myosteatosis on computed tomography (CT) scans had a significantly lower mortality risk than non-obese patients.

For the retrospective study, recently published in Radiology, researchers reviewed CT scans for 7,076 patients who underwent curative resection for NSCLC. Obese patients, those with a body mass index (BMI) > 25, comprised 35.5 percent of the cohort, according to the study.

The study authors found that obese patients without CT evidence of myosteatosis or LSMM had a 23 percent lower likelihood of death in contrast to non-obese patients.

“… This study found an association between body mass index (BMI)–defined obesity and improved overall survival among patients with non–small cell lung cancer after curative resection for whom CT-measured skeletal muscle mass and radiodensity were within normal ranges,” wrote lead study author Ji Hyun Lee, M.D., who is affiliated with the Department of Radiology at the Sungkyunkwan University School of Medicine at Samsung Medical Center in Seoul, Korea, and colleagues.

For the patients without evidence of LSMM or myosteatosis on CT, the researchers noted the positive associations between obesity and reduced mortality rates primarily occurred in men (hazard ratio (HR) of 28 percent) and those who had ever smoked (HR of 71 percent).

Citing literature that suggests a reduced impact of smoking on cytokines and adipokines in obese patients, the study authors said other research indicates that adipose tissue may help mitigate the systemic effects of harmful lipophilic chemicals.

“This hypothesis appears convincing in explaining the varying manifestations of the obesity paradox based on smoking status. These protective effects are prominent among metabolically healthy obese individuals as opposed to their metabolically unhealthy counterparts, who may experience dysregulated lipolysis, leading to the release of these toxic chemicals,” added Lee and colleagues.

The researchers also noted that 27.5 percent of the total study cohort had NSCLC recurrence or died within the 60.9-month median follow-up period. Obese patients had a 13 percent lower risk of NSCLC recurrence or death in comparison to non-obese patients, according to the study authors.

(Editor’s note: For related content, see “CT Study Reveals Key Indicators for Angiolymphatic Invasion in Non-Small Cell Lung Cancer,” “CT Study Links Better Five-Year Prognosis with Minor Ground Glass Opacity Component in NSCLC Lung Nodules” and “Dual-Energy CT Improves Diagnosis of Metastatic Lymph Nodes with Non-Small Cell Lung Cancer.”)

In regard to study limitations, the authors noted the lack of longitudinal assessments of body weight and skeletal status, and a small number of patients with obesity and low skeletal muscle mass. The researchers also cautioned against broad extrapolation of the study findings, noting that the cohort was comprised entirely of Korean patients who have a predominance of early-stage NSCLC and a low prevalence of morbid obesity.