Abstract Introduction Spontaneous tumor lysis syndrome (STLS) is rare in solid tumors but highly lethal. Older adults may be especially vulnerable due to comorbidity and homeostenosis. Our objective was to synthesize reported cases among older adults with solid tumors and describe clinical features, prognostic factors, and outcomes. Methods We systematically reviewed reports of patients ≥65 years with STLS from solid tumors, excluding hematologic malignancies or recent cytotoxic therapy. PubMed and Embase were searched through 16 September 2025, plus one hand-identified case. Data extracted included demographics, tumor type, metastatic activity, laboratory results, renal failure, and mortality. Hypothesis-generating analysis included Fisher’s exact, Mann–Whitney U tests, and the area under the curve (AUC) with a Youden’s J-derived cutoff (to summarize phosphate’s discrimination for death). Results Eighteen publications (20 patients) met criteria; no Japanese cases, highlighting a potential regional data gap. Overall mortality was 74%. Renal failure (14 of 20) strongly predicted death (13/14 vs 0/4, P .002). Phosphate was higher in non-survivors (median 7.1 vs 5.25 mg/dL; P = .040) and discriminated death well (AUC = 0.865); a Youden-optimal phosphate threshold ≈6.0 mg/dL signaled high mortality risk. Tumors were almost exclusively metastatic; 88% involved the liver. Conclusions Although rare, with evidence limited to case reports inherently at high risk for publication bias and imprecision, STLS is almost exclusively associated with metastatic disease, usually with hepatic involvement. It is lethal, particularly when accompanied by renal failure and/or hyperphosphatemia (6 mg/dL) in older adults with solid tumors. Early recognition and management are critical.
Pettit et al. (Wed,) studied this question.