Childhood obesity at cancer diagnosis leads to worse survival outcomes

A recent study published in Cancer has found that children who have obesity at the time of their cancer diagnosis experience significantly poorer survival outcomes compared to their peers without obesity. The findings indicate a notable reduction in both event-free survival (EFS) and overall survival (OS) rates, underscoring the need for further research into the underlying mechanisms and potential interventions.

Study Overview and Methodology

Researchers examined the relationship between obesity and cancer outcomes in children aged 2 to 18 years who were newly diagnosed with cancer. The study drew data from the Cancer in Young People in Canada database, covering cases from 2001 to 2020. A total of 11,291 children with cancer were included, with a median age at diagnosis of 7.6 years.

Among the participants, 55.0% were boys, and 10.5% were classified as having obesity at the time of diagnosis. The cohort included children with various types of cancer:

• Leukaemias (37.1%)
• Lymphomas (14.5%)
• Central nervous system (CNS) tumours (21.8%)
• Other solid tumours (26.6%)

Key Findings on Survival Outcomes

The study revealed a significant disparity in survival rates between children who had obesity at diagnosis and those who did not.

Event-Free Survival (EFS) Outcomes

• The median follow-up period for EFS was 4.5 years.
• The five-year EFS rate was 77.5% for children with obesity, compared to 79.6% for children without obesity (P = .04).
• Multivariable analyses confirmed that obesity at diagnosis was associated with a significantly increased risk of adverse outcomes, with an adjusted hazard ratio (aHR) of 1.16 (95% CI, 1.02-1.32; P = .02).

Overall Survival (OS) Outcomes

• The median follow-up period for OS was 4.7 years.
• The five-year OS rate was 83.0% for children with obesity, compared to 85.9% for those without obesity (P = .004).
• Multivariable analyses demonstrated a stronger association between obesity and reduced OS, with an adjusted hazard ratio (aHR) of 1.29 (95% CI, 1.11-1.49; P = .001).

Influence of Age and Gender

According to the researchers, the negative impact of obesity on survival outcomes was more pronounced in certain subgroups:

“The adverse impact of obesity on EFS and OS was more prominent in girls and in children younger than 10 years,” the researchers noted.

Interestingly, for children who continued to have obesity in the years following their cancer diagnosis, there was no significant difference in survival rates when compared to children without obesity. This finding was consistent across all cancer types within the study cohort.

Causes of Death and Obesity’s Role

The study also examined whether the causes of death differed between children with and without obesity. The results showed no significant differences in the primary causes of mortality, which included:

• Disease progression or relapse – 88.9%
• Treatment-related toxicity – 4.4%
• Other causes – 6.8%

Potential Mechanisms and Future Research

While the exact mechanisms by which obesity contributes to poorer cancer outcomes remain unclear, the researchers highlighted specific trends within subgroups of children diagnosed with acute lymphoblastic leukaemia (ALL) and CNS tumours:

“Although obesity at cancer diagnosis was independently associated with inferior survival across the entire cohort, this finding was likely driven by the trends detected in children with ALL and CNS tumours,” the researchers wrote.

This suggests that certain cancer types may be more affected by the presence of obesity, necessitating further investigation into biological and physiological factors at play.

Furthermore, the researchers emphasised the importance of understanding whether changes in body weight during treatment could impact survival outcomes:

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

Funding and Disclosures

This research received partial funding from the Fonds de Recherche du Québec–Santé. One of the study’s authors disclosed conflicts of interest; for full details, readers are encouraged to refer to the original publication.

Conclusion

This study provides compelling evidence that children with obesity at the time of a cancer diagnosis are at a significantly higher risk of experiencing inferior survival outcomes. While obesity did not appear to affect the cause of death, its association with poorer EFS and OS rates—particularly in younger children and girls—warrants urgent attention. Future research is essential to explore potential interventions, including weight management strategies during treatment, to improve survival outcomes in paediatric oncology.