Anthropometric indicators and risk of relapse or second malignant neoplasms in childhood cancer survivors: a scoping review

Growing evidence suggests that diet and nutrition play a critical role in cancer development and progression. However, most research focuses on adult populations, leaving significant knowledge gaps regarding childhood cancer survivors (CCS). Scoping reviews can help identify these gaps and inform clinical decision-making and cancer control strategies. This review initially aimed to identify and map dietary and nutritional risk factors potentially associated with relapse, recurrence, or second malignant neoplasms (SMNs) in CCS. However, during the review process, only studies reporting anthropometric indicators were identified, and evidence was available for two outcomes (relapse and SMNs). This scoping review was conducted in accordance with the Joanna Briggs Institute Manual for Scoping Reviews and the PRISMA-ScR guidelines. Studies were eligible if they included: Population – CCS; Concept – dietary and nutritional factors; Context – relapse, recurrence, or SMNs. Cohort and case–control studies were included from PubMed/MEDLINE, Embase, Scopus, Web of Science, and LILACS, without restrictions on language or publication year. Additional studies were identified using AI-based tools and bibliographic alerts. Results were synthesized narratively and thematically mapped. Methodological quality was assessed using the Newcastle–Ottawa Scale. Eight studies (seven cohorts, one case–control), published between 2007 and 2025, were included, covering a total of 39,847 CCS. Acute lymphoblastic leukemia was the most commonly studied cancer type. Four studies examined relapse, three focused on SMNs, and one addressed both outcomes. Follow-up durations ranged from 2.7 to 20.1 years. All studies reported controlling for confounding factors, and only one disclosed financial conflict. Nutritional status was primarily assessed using BMI (six studies); one study also included body composition, and another employed multiple anthropometric indices. Five studies found that excess body weight significantly increased the risk of relapse or SMNs. None of the studies comprehensively evaluated dietary intake or other nutritional dimensions. All studies were classified as being of good quality and at low risk of bias, according to the Newcastle–Ottawa Scale. Although obesity may be associated with an increased risk of relapse and SMNs in CCS, current evidence is limited, heterogeneous, and does not include dietary and other nutritional factors. Well-designed, longitudinal studies using standardized and comprehensive nutritional assessments are necessary to understand these associations better and support evidence-based survivorship guidelines.