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Printed on 7/20/2026
For informational purposes only. This is not medical advice.
The Geriatric-8 (G8) is a rapid screening instrument derived from Mini Nutritional Assessment items plus age. It is widely used in older adults, especially oncology pathways, to identify those who may benefit from comprehensive geriatric assessment. Lower G8 scores suggest greater vulnerability, and a threshold of 14 or below is commonly considered abnormal.
Formula: G8 total = sum of 8 item scores (range 0-17). Common abnormal threshold: <=14.
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The G8 consists of 8 items directly adapted from the Mini Nutritional Assessment (MNA) plus an age item: (1) decreased food intake over the past 3 months; (2) weight loss over the past 3 months; (3) mobility; (4) neuropsychological problems (dementia, depression, cognitive impairment); (5) BMI category; (6) polypharmacy (taking more than 3 medications per day); (7) self-rated health compared with other people of the same age; and (8) age category (below 80, 80 to 85, above 85). Each item has 2 to 4 ordinal response options weighted by their predictive value for geriatric vulnerability.
Item scores are summed to yield a total G8 score ranging from 0 to 17. Higher scores indicate better nutritional status, better function, and lower geriatric vulnerability. Lower scores indicate greater impairment across multiple domains. The scoring is counterintuitive in that higher = better, unlike many other frailty tools. The maximum possible score of 17 represents the least vulnerable profile across all items: no food intake decline, no weight loss, full mobility, no neuropsychological problems, BMI 23 or higher, no polypharmacy, better self-rated health, and age below 80.
A G8 score of 14 or below is the validated threshold for an abnormal screen, indicating that comprehensive geriatric assessment (CGA) should be considered. This threshold was derived to maximize sensitivity for identifying older adults with geriatric vulnerability who may benefit from CGA before cancer treatment. A score of 15 or higher is considered a normal screen in most protocols, though clinical judgment should prevail for borderline scores. The G8 is designed as a triage tool — its purpose is to identify who should receive CGA, not to replace CGA itself.
Oncologists, geriatric oncology teams, cancer nurses
The G8 was specifically developed and validated for use in older adults with cancer to identify those who require comprehensive geriatric assessment (CGA) before initiating chemotherapy, radiation, immunotherapy, or major cancer surgery. Multiple randomized controlled trials and international oncology guidelines (SIOG, ESMO, ASCO) recommend routine G8 screening for patients aged 70 and older at oncology consultation. A G8 score of 14 or below triggers CGA referral. G8-guided CGA has been shown to identify previously unrecognized geriatric problems in 30 to 60 percent of screened patients and to change treatment decisions in a meaningful proportion of cases.
Oncologists, clinical pharmacists, oncology nurses
G8 screening before chemotherapy identifies older adults at high risk for grade 3 to 5 treatment toxicity, treatment discontinuation, and unplanned hospitalization. Abnormal G8 scores predict chemotherapy toxicity with similar accuracy to dedicated toxicity prediction tools (e.g., Cancer and Aging Research Group [CARG] score). In practice, G8 is used as an initial rapid screen — patients with G8 below 14 are referred for CGA, which then informs individualized dose modification, supportive care planning, and treatment selection. Identifying high-risk patients before treatment initiation allows proactive intervention.
Dietitians, physiotherapists, geriatricians
As a tool derived from the Mini Nutritional Assessment, G8 is sensitive to nutritional and functional vulnerability in older adults, including weight loss, food intake decline, mobility limitation, and low BMI. An abnormal G8 identifies patients who benefit from pre-treatment nutritional intervention, exercise prehabilitation, and multidisciplinary geriatric assessment. In cancer patients, pretreatment nutritional status significantly affects treatment tolerance, surgical outcomes, and recovery — making early G8-triggered nutritional intervention clinically impactful.
Multidisciplinary cancer teams, care coordinators, social workers
The G8 score provides an objective, standardized frailty screening result that can be documented in the oncology record, communicated across multidisciplinary teams, and used to justify CGA referrals and treatment modifications. The brief 5-minute administration time enables routine integration into oncology consultation workflows without disrupting clinical flow. G8 documentation supports audit of geriatric screening rates, compliance with oncology guideline recommendations, and quality benchmarking across cancer programs.
Cancer program directors, quality improvement teams
Major international oncology guidelines from SIOG (International Society of Geriatric Oncology), ESMO, and ASCO recommend screening all patients aged 70 and older with a validated tool such as the G8 before cancer treatment initiation. Implementing routine G8 screening in cancer programs demonstrates compliance with these guideline recommendations, supports accreditation requirements, and aligns with best practice standards. G8 screening rates and CGA referral rates are increasingly used as quality metrics in geriatric oncology program evaluation.
The G8 threshold of 14 or below was chosen to maximize sensitivity for identifying geriatric vulnerability — this means some patients who screen abnormal will not have significant issues identified on full CGA. This is intentional: missing a vulnerable patient (false negative) carries greater clinical consequences in oncology than an unnecessary CGA referral (false positive). Expect that 40 to 60 percent of patients aged 70 and older will screen abnormal, and use CGA to triage further.
The G8 identifies who NEEDS CGA — it does not constitute a CGA itself. An abnormal G8 triggers referral for comprehensive assessment across geriatric domains (cognition, function, nutrition, comorbidities, polypharmacy, social support, mood), which then informs treatment decisions. Never use the G8 score alone to make treatment decisions — use it to triage access to the CGA that informs those decisions.
The self-rated health item (How does the patient rate their health compared with peers?) is one of the most powerful predictors in the G8, despite appearing subjective. Patients who rate their health as 'not as good' or 'do not know' compared with peers have consistently worse outcomes in oncology and geriatric populations. Pay close attention to this item — patients who score poorly here should raise clinical concern even if other items appear relatively preserved.
The polypharmacy item (more than 3 medications/day) captures drug burden independently of disease burden. Older adults taking more than 5 medications have high rates of drug-drug interactions, inappropriate prescribing, and treatment toxicity. An abnormal polypharmacy item should trigger medication reconciliation and pharmacy review as part of the CGA process, particularly before initiating cytotoxic chemotherapy.
G8 can be repeated during cancer treatment to track changes in nutritional and functional status over time. A declining G8 during treatment (worsening score) indicates that the patient is experiencing treatment-related vulnerability deterioration and may benefit from treatment modification, dose reduction, supportive care escalation, or palliative care discussion. Routine serial G8 measurement is increasingly used in geriatric oncology programs to detect subclinical functional decline before it becomes clinically overt.
G8 has been validated in colorectal, breast, lung, hematologic, genitourinary, and other cancer types. Its predictive validity for geriatric vulnerability, treatment toxicity, and mortality is consistent across tumor types and cancer stages, making it a broadly applicable tool for any older adult cancer patient regardless of primary diagnosis. This cross-cancer validity makes it ideal for oncology units treating mixed cancer populations.
G8 identifies who needs CGA, while the [Frailty Index-40](/tools/frailty-index-40) quantifies the frailty burden found during that CGA. In oncology, G8 screening followed by FI-40-informed CGA provides the most complete vulnerability picture for treatment planning. Patients with G8 below 14 AND FI-40 above 0.30 represent the highest-risk subgroup where treatment modifications and early palliative care integration have the greatest potential impact on quality of life.
The age item (0 to 2 points based on age bands) contributes a maximum of 2 points to the G8 total. Younger patients aged below 80 score 2 points (maximum, best outcome), while patients above 85 score 0. The age item alone cannot cause an abnormal G8 — a 75-year-old scoring maximum on every other item would still score 15 (normal). This means the G8 captures clinical vulnerability above and beyond chronological age.
A cutoff <=14 is commonly used to select older adults who should receive comprehensive geriatric assessment.
Lower G8 scores indicate higher vulnerability and support referral for comprehensive geriatric assessment.
Use in older adults, especially oncology or complex chronic-care pathways, when rapid geriatric vulnerability triage is needed.
G8 is screening-focused and may miss domain-specific issues unless followed by broader multidimensional assessment.
For related assessments, see MNA-SF, FRAIL Scale and Clinical Frailty Scale.
Disclaimer: This tool is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about your health.
April 21, 2026 · trust-baseline
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