Risk Factors for 30-Day Hospital Readmission in Patients With Cancer: A Systematic Review With Emphasis on Older Adults

Thirty-day hospital readmission is a key indicator of healthcare quality, particularly in patients with cancer who are at an increased risk due to multimorbidity, treatment-related complications, and functional decline. Although older adults represent a vulnerable subgroup, evidence specific to geriatric oncology remains limited. This systematic review aimed to identify and synthesise risk factors for 30-day hospital readmission among patients with cancer, with particular emphasis on older adults. A systematic search of MEDLINE, Embase, and the Cochrane Library (January 2015 to March 2026) was conducted in accordance with PRISMA 2020 guidelines. Eight observational studies were included. Risk factors were categorised into clinical, functional, treatment-related, and social domains. Clinical factors, including comorbidity burden and abnormal laboratory parameters (particularly hypoalbuminaemia), were the most consistently reported predictors. Functional impairment and geriatric-specific factors were strongly associated with the risk of readmission in studies focusing on older adults. Treatment-related factors such as prolonged length of stay and polypharmacy, along with social determinants including limited social support, further contributed to increased risk. Considerable heterogeneity across study populations, methodologies, and outcome reporting precluded meta-analysis. Overall, the evidence suggests that readmission risk in patients with cancer is multifactorial, with consistent direction of association across studies despite variability in magnitude. However, the limited number of geriatric-specific studies highlights a critical gap in the literature. These findings support the need for multidimensional risk assessment and targeted transitional care interventions. Future research should prioritise prospective, geriatric-focused studies and the development of validated risk prediction models.