ECOG Performance Status — Patient Functional Ability Scale

Developed by the Eastern Cooperative Oncology Group, the ECOG performance status is an objective metric used globally to quantify a cancer patient's general well-being and daily living abilities. The scale ranges from 0 (fully active, able to carry on all pre-disease performance without restriction) to 5 (deceased).

Intermediate scores capture progressive levels of functional impairment: grade 1 reflects restriction in strenuous activity but full ambulation; grade 2 indicates an individual is ambulatory and capable of all self-care but unable to work, up and about more than 50% of waking hours; grade 3 denotes confinement to bed or chair for more than 50% of waking hours with limited self-care; and grade 4 indicates complete disability and confinement. The score serves as an essential prognostic marker independent of tumour stage.

The ECOG performance status helps oncologists balance the potential benefits of aggressive therapy against the risk of severe toxicity. Patients with good performance status (ECOG 0-1) are generally better able to tolerate intensive chemotherapy regimens, targeted therapies, or surgery. Conversely, a higher score (ECOG 3-4) signals that aggressive therapy might cause significant physical harm, leading clinicians to recommend tailored, less toxic options, dose adjustments, or a focus on palliative symptom relief. It is also an essential eligibility criterion for participation in cancer clinical trials.

ECOG status is not a laboratory or molecular test; it is a clinical assessment conducted during routine appointments. The oncologist evaluates the score by interviewing the patient and family about daily mobility, self-care capabilities, work activities, and the proportion of daylight hours spent resting in bed or seated.

The ECOG scale is applied across all cancer types and stages. It is equally relevant in solid tumours (such as lung, gastrointestinal, and breast cancers) and haematological malignancies (such as leukaemia, lymphoma, and multiple myeloma), providing a universal language for physical capability.

Clinical treatment protocols directly depend on ECOG scores. For instance, intensive triplet chemotherapy regimens are typically reserved for patients with an ECOG of 0 or 1. Patients with an ECOG of 2 might receive single-agent therapy or reduced dosages. For an ECOG score of 3 or 4, systemic chemotherapy is often avoided, shifting the focus toward supportive care, palliative radiotherapy, and quality-of-life optimisation.