Misperception of Body Weight After Childhood Cancer

BACKGROUND: Misperception of body weight can negatively impact the weight management efforts of childhood cancer survivors (CCSs). Both being overweight or underweight are associated with chronic health conditions commonly observed in CCS; therefore, accurate weight perception is critical for reducing long-term health risks. AIM: To assess the agreement between objectively measured body mass index (BMI) and self-perceived body weight in adult CCS, and to identify predictors of BMI underestimation and overestimation. METHODS: In this prospective, multicenter cohort study, we invited CCS aged ≥18 years, diagnosed <20 years, who had survived ≥5 years post-diagnosis. Participants were treated between 1976 and 2018 with chemotherapy and/or heart-related radiotherapy (RT). Trained medical staff measured height and weight and assessed body weight perception using pictorial images. We evaluated agreement between actual BMI and perceived weight status using Cohen's Kappa (ĸ) and analyzed predictors of misperception with multivariable multinomial logistic regression. RESULTS: (IQR: 21.6‒27.1); 4% were underweight, 30% overweight, and 10% obese 25 years after diagnosis. BMI and weight perception agreement was moderate (ĸ = 0.46, p < 0.001). Among overweight CCS, 37% underestimated their weight. Among both under and overweight CCS, 25% overestimated their weight. Overestimation was more likely among former smokers (odd ratio [OR] = 2.52, 95%CI = 1.31; 4.88), those with multiple chronic health conditions (2.49, 1.13; 5.46), and those who received cranial radiation (2.06, 1.10; 3.83). CONCLUSIONS: Identifying and addressing weight misperception, especially in CCS with chronic health conditions and after cranial radiation, could improve weight management strategies.