Obesity at Cancer Diagnosis Linked to Worse Survival Outcomes in Pediatric Patients

Being obese at diagnosis is an independent negative risk factor for poor survival outcomes in children and adolescents with cancer, especially among those with acute lymphoblastic leukemia (ALL) and central nervous system (CNS) tumors, according to a study published today in Cancer.¹

Childhood obesity may result in various debilitating health outcomes, like type 2 diabetes, obstructive sleep apnea, and hypertension.² Research is increasingly suggesting that being overweight or obese at diagnosis contributes to adverse outcomes in children with cancer.¹ However, the results on the prognostic impact of obesity in childhood cancer remain inconsistent across studies; past studies vary based on cancer types and were not population based.

Consequently, the present researchers explained that the biological insights and clinical significance of obesity among pediatric patients with cancer remain unclear and warrant further investigation. Therefore, they conducted a retrospective cohort study to assess the prevalence of obesity and its prognostic significance in Canadian children and adolescents diagnosed with cancer.

Pediatric patients considered obese at cancer diagnosis are linked to significantly worse survival outcomes. | Image Credit: Protsenko Dmitriy - stock.adobe.com

The researchers conducted the study using the Cancer in Young People in Canada (CYP-C) database, a pan-Canadian surveillance program that collected in-depth clinical data from all patients with cancer aged 15 and younger from 2001 and 2015; it was expanded from 2015 onward to include all Canadian patients with cancer younger than 19 years. They included all children and adolescent patients who were diagnosed with cancer between the ages of 2 and 17 years and treated at one of the 17 pediatric oncology centers in Canada between 2001 and 2020.

Using univariate and multivariable Cox proportional hazards models, the researchers compared event-free survival (EFS) and overall survival (OS) among pediatric patients with cancer and obesity vs those with cancer and healthy weights, both overall and by cancer type. They measured EFS from the time of diagnosis to the first event (disease progression, relapse, second malignancies, or death from any cause) or the date of last follow-up for those without an event. Conversely, OS was measured from the date of diagnosis to death from any cause or the date of last follow-up for those who remained alive.

The secondary objectives were to identify outcome predictors based on obesity status and to describe obesity prevalence at baseline and post cancer therapy. Overall, the researchers used the CDC definition of childhood obesity, which defined it as those with a body mass index (BMI) of at least the age- and sex-adjusted 95th percentile.

Among those in the CYP-C database, 13,073 patients were eligible for this study. However, 1782 (13.6%) were excluded since their weight and height measurements were recorded more than 30 days from the date of initial diagnosis. Consequently, 11,291 patients were analyzed.

The median (IQR) age at cancer diagnosis was 7.6 (4.2-12.5) years, and 55.0% of patients were boys (n = 6214). In terms of cancer type, the cohort comprised 37.1% leukemias (n = 4192), including 82.5% with ALL (n = 3458), 14.5% with lymphomas (n = 1638), 21.8% with central nervous system (CNS) tumors (n = 2458), and 26.6% with non-CNS solid tumors (n = 3003).

Of the cohort, 10.5% (n = 1181) were obese at diagnosis. Patients considered obese at diagnosis were older than patients with healthy weights (median [IQR] age, 8.6 [4.5-12.7] vs 7.5 [4.1-12.5] years). Obesity prevalence also varied by cancer subgroup, with it affecting 11.3% of patients with leukemias, 11.4% with lymphomas, 9.7% with CNS tumors, and 9.4% with non-CNS solid tumors (P = .02).

Additionally, the median (IQR) follow-up for EFS and OS was 4.5 (1.9-5.0) and 4.7 (2.6-5.2) years, respectively. The researchers determined that the overall 5-year EFS (77.5% vs 79.6%; P = .04) and OS (83.0% vs 85.9%; P = .004) in patients who were obese at diagnosis were inferior to those with healthy weights. Therefore, in multivariable analyses, obesity at diagnosis was significantly associated with decreased 5-year EFS (adjusted HR [aHR], 1.16; 95% CI, 1.02-1.32; P = .02) and OS (aHR, 1.29; 95% CI, 1.11-1.49; P = .001).

In terms of cancer type, the adverse prognostic impact of obesity was particularly notable among those with ALL and CNS tumors. Of those with ALL, 11.4% were obese. Obesity at diagnosis in patients with ALL was significantly associated with inferior 5-year EFS (84.5% vs 89.8%; P < .001) and OS (89.8% vs 94.4%; P < .001) vs patients with healthy weights. In multivariable models, obesity remained significantly associated with inferior EFS (aHR, 1.55; 95% CI, 1.17-2.04) and OS (aHR, 1.75; 95% CI, 1.23-2.49; P = .002).

Obesity prevalence also varied by CNS tumor subtypes, ranging from 5.5% among patients with medulloblastomas to 17.1% in those with pineal tumors and tumors of the sellar region (P = .002). Among the entire CNS tumor cohort, obesity at diagnosis was significantly associated with inferior 5-year EFS (68.1% vs 74.2%; P = .02) and OS (73.1% vs 79.3%; P = .01). Regardless of CNS tumor subtype, obesity at diagnosis remained independently associated with decreased EFS (aHR, 1.38; 95% CI, 1.09-1.76; P = .008) and OS (aHR, 1.47; 95% CI, 1.13-1.91; P = .004) in multivariable models.

The researchers acknowledged their study’s limitations, including that they excluded 13.6% of the cohort (n = 1782 patients) because of missing weight and height measurements within 30 days from the date of diagnosis; this potentially contributed to selection bias. Despite their limitations, they used their findings to suggest areas for further research.

“Further studies are needed to better characterize the pathophysiologic mechanisms linking obesity and survival in pediatric oncology,” the authors concluded. “Furthermore, it is crucial to determine whether normalization of weight during treatment positively affects cancer outcomes to inform future trial designs and supportive care interventions.”

References

1. Sassine S, Ilinca AP, Coltin H, et al. Impact of obesity on outcome in children diagnosed with cancer in Canada: A report from Cancer in young people in Canada. Cancer. 2025;131(2). doi:10.1002/cncr.35673

2. Daniels SR, Arnett DK, Eckel RH, et al. Overweight in children and adolescents: pathophysiology, consequences, prevention, and treatment. Circulation. 2005;111(15):1999-2012. doi:10.1161/01.CIR.0000161369.71722.10