The number of patients with solid tumours requiring intensive care is increasing as cancer survival improves and oncological treatments become more complex. Intensive care unit (ICU) admission decisions should not be based on cancer diagnosis, metastatic status or palliative treatment intent alone. This narrative review presents a practical, multidisciplinary framework for assessing critically ill patients with solid tumours. It integrates acute illness severity and reversibility, organ failure, baseline performance status and frailty, cancer trajectory, remaining treatment options, expected functional recovery and patient preferences. We discuss contemporary anticancer treatment toxicities, cancer-associated thromboembolic disease, older adults, palliative care, communication and ethical decision-making. We also propose an algorithm ranging from full ICU support to a time-limited ICU trial with predefined reassessment or comfort-focused care. Early joint assessment by oncology and intensive care teams, followed by dynamic reassessment, may reduce both inappropriate escalation and premature exclusion from potentially beneficial organ support. Future research should prioritize structured pathways, improved prognostic tools and outcomes beyond survival, including functional recovery, quality of life and the ability to resume meaningful cancer treatment.