Lifetime obesity affected more than half of patients receiving systemic anticancer therapy in England, according to a large real-world analysis that found obesity measured at treatment initiation substantially underestimated previous exposure across a range of cancer types.
Lifetime Obesity Far Exceeds Baseline Rates
Obesity is a recognised risk factor for several cancers and has been associated with differences in patient outcomes. However, most cancer research evaluates obesity using body mass index measurements recorded at treatment initiation, potentially overlooking earlier exposure that may influence disease development and prognosis.
To explore this issue, investigators analysed longitudinal body mass index records from linked primary care and systemic anticancer therapy datasets in England. The study included 79,271 patients who received their first systemic anticancer treatment between 2013 and 2023.
The cohort had a median age of 66.5 years at first treatment. Women accounted for 54.2% of patients, while 89.0% were of White ethnicity. Researchers assessed both obesity prevalence at treatment initiation and lifetime obesity prevalence, defined by a body mass index of at least 30 kg/m² at any point before or at treatment start.
Obesity Burden Varied Across Cancer Types
Across all cancers, age standardised obesity prevalence at treatment initiation was: 26.4%; 95% CI: 26.0–26.9. Rates differed substantially according to cancer type.
The lowest prevalence was observed in pancreatic cancer: 13.7% (95% CI: 11.6–15.9). The highest prevalence occurred in uterine cancer: 36.3% (95% CI: 29.9–42.7).
In contrast, lifetime obesity prevalence was markedly higher. Across all cancer types, lifetime obesity was identified in: 53.5% (95% CI: 53.2–53.9) of patients.
Lifetime obesity prevalence ranged from: 51.1% (95% CI: 50.3–52.0) in lung cancer to: 63.0% (95% CI: 58.8–67.2) in hepatocellular carcinoma. The findings indicate that reliance on body mass index measurements recorded only at treatment initiation may fail to capture the true extent of obesity exposure among patients receiving cancer therapy.
Implications for Cancer Research
The study also found that obesity prevalence at treatment initiation varied according to cancer type, age, sex, ethnicity, and socioeconomic deprivation, highlighting the complexity of obesity related risk across different patient populations.
Overall, the researchers concluded that approximately one in four patients were living with obesity when systemic treatment began, whereas more than one in two had experienced obesity at some point during their lifetime. These findings suggest that incorporating lifetime obesity into prognostic models and outcomes research may improve understanding of cancer risk, treatment response, and long-term outcomes, with important implications for precision medicine.
Reference
Perletta V et al. Real-world obesity prevalence and history in 79 271 patients receiving systemic anticancer therapy across 13 cancer types in England (2013-2023). ESMO Real World Data and Digital Oncology. 2026;12:100700.
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