What is the G8 screening tool?

The Geriatric-8 (G8) is a validated 8-item frailty screening tool developed for use in older adults with cancer. It is derived from the Mini Nutritional Assessment (MNA) plus an age item and scores from 0 to 17. A score of 14 or below indicates abnormal screening and triggers referral for comprehensive geriatric assessment (CGA) before cancer treatment initiation.

What G8 threshold is commonly used?

A score of 14 or below is the validated threshold for an abnormal G8 screen, indicating comprehensive geriatric assessment should be considered. A score of 15 or higher is generally considered normal. This threshold maximizes sensitivity for identifying geriatric vulnerability in older cancer patients.

What does a G8 score of 14 or below mean?

A G8 score of 14 or below indicates geriatric vulnerability that warrants comprehensive geriatric assessment. It does not diagnose a specific condition — rather, it signals that the patient is at higher risk for treatment toxicity, functional decline, and adverse outcomes, and should receive a full CGA before cancer treatment to identify modifiable geriatric problems.

Where is G8 commonly used?

G8 is widely used in geriatric oncology settings to screen older adults before cancer treatment. It is recommended by SIOG, ESMO, and ASCO for routine use in patients aged 70 and older at oncology consultation. It is also used in other older-adult clinical pathways where rapid geriatric vulnerability triage is needed.

Does a normal G8 rule out frailty?

No. G8 is a screening tool with high sensitivity but imperfect specificity. A normal G8 (15 or higher) reduces the likelihood of significant geriatric vulnerability but does not rule it out. Clinical judgment should prevail — patients with borderline scores or strong clinical frailty signals should still be referred for CGA regardless of G8 score.

What are the 8 items in the G8 tool?

The 8 items are: (1) food intake decline in the past 3 months, (2) weight loss in the past 3 months, (3) mobility, (4) neuropsychological problems (dementia, depression), (5) BMI category, (6) polypharmacy (more than 3 medications/day), (7) self-rated health compared with peers, and (8) age category. Items 1 through 7 are adapted from the Mini Nutritional Assessment.

How does G8 differ from the Frailty Index-40?

G8 is a brief 8-item oncology screening tool that identifies who needs comprehensive geriatric assessment (CGA). The Frailty Index-40 is a comprehensive continuous frailty measure quantifying the burden of 40 health deficits. In oncology workflows, G8 is used to triage access to CGA, while FI-40 quantifies the frailty severity found during CGA to guide treatment planning.

Can G8 predict chemotherapy toxicity?

Yes. Abnormal G8 scores predict grade 3 to 5 chemotherapy toxicity, treatment discontinuation, and unplanned hospitalization in older cancer patients. Its predictive accuracy for toxicity is comparable to dedicated toxicity prediction tools. This makes pre-chemotherapy G8 screening clinically valuable for identifying patients who may need dose modifications or alternative regimens.

Should G8 be repeated during treatment?

Yes. Repeating G8 during treatment allows monitoring of treatment-related changes in nutritional and functional status. A worsening G8 score during treatment indicates increasing vulnerability and may prompt dose modifications, supportive care escalation, or palliative care discussions. Serial G8 assessment is increasingly incorporated into geriatric oncology program monitoring protocols.

What are the limitations of the G8?

Main limitations: (1) designed primarily for oncology settings — performance outside oncology is less well characterized; (2) high sensitivity means many patients will screen abnormal, requiring downstream CGA resources; (3) acute illness can temporarily worsen scores, potentially overestimating frailty; (4) items 1 through 7 are nutrition-focused and may underdetect vulnerability primarily in other domains (cognition, functional status).

Online Medical Tools — G8 Score

Printed on 9/3/2026

For informational purposes only. This is not medical advice.

Geriatrics

G8 Score

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.

Food intake decline

Weight loss in 3 months

Mobility

Neuropsychological problems

BMI category

Takes more than 3 prescription drugs/day

Self-perceived health vs peers

Age points

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How It Works

Complete the 8 Scored Items

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.

Sum Scores to Yield Total 0 to 17

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.

Apply the Abnormal Threshold of 14 or Below

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.

Who Uses the G8 Score

Geriatric Oncology Triage Before Cancer Treatment

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.

Pre-Chemotherapy Toxicity Risk Identification

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.

Nutritional and Functional Vulnerability Detection

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 Team Communication and Documentation

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.

International Oncology Guideline Compliance

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.

Pro Tips

G8 Is Designed to Be Maximally Sensitive, Not Specific

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.

G8 Is Not a CGA Replacement

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.

Self-Rated Health Item Is Highly Predictive

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.

Polypharmacy Item Captures Drug Burden Risk

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.

Serial G8 Monitoring Tracks Treatment Response

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 Performs Well Across Cancer Types

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.

Combine G8 With Frailty Index for Maximum Precision

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.

Age Item Does Not Drive the G8 Score Alone

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.

Common Questions About Your Results

Yes, if clinical gestalt suggests significant frailty despite a normal G8. The G8 has high sensitivity but imperfect specificity. Borderline normal scores (14 to 16) in patients with strong clinical frailty signals — severe functional limitation, significant cognitive impairment, extreme weight loss not fully captured by the single weight-loss item — should still trigger CGA referral. The G8 is a triage guide, not an infallible gatekeeper. Clinical judgment overrides tool score when there is substantial clinical concern.

For patients who cannot reliably self-report due to cognitive impairment, dementia, or language barriers, G8 items can be completed using caregiver or family proxy report, available medical records, and direct clinician observation. Proxy reporting is particularly applicable for food intake, weight loss, mobility, and self-rated health items. Document that the assessment was proxy-completed. This approach preserves the tool's utility in cognitively impaired populations while acknowledging potential proxy reporting bias.

G8 was developed and primarily validated in outpatient oncology settings. Its validity in acute or emergency settings is less established. In these contexts, acute illness may transiently worsen food intake, mobility, and self-rated health scores, potentially overestimating frailty at that moment. For oncology patients who present acutely, G8 screening is best performed after acute illness has resolved or been stabilized, when items more accurately reflect the patient's stable functional and nutritional baseline.

G8 was designed and validated specifically for oncology settings. It can be used as a general geriatric vulnerability screen outside oncology, given its derivation from the MNA and its coverage of nutritional and functional domains. However, its threshold and interpretation were validated in oncology populations, and its comparative performance against other geriatric screening tools (VES-13, ISAR) outside oncology is less well characterized. For non-oncology clinical settings, tools like the [Clinical Frailty Scale](/tools/clinical-frailty) or [FRAIL Scale](/tools/frail-scale) may be more contextually appropriate.

After an abnormal G8, the patient is referred for comprehensive geriatric assessment (CGA), typically conducted by a geriatrician, geriatric oncology team, or trained geriatric nurse specialist. CGA covers cognition (MMSE, MoCA), functional status (ADL, IADL), nutrition (MNA Full), comorbidity burden, polypharmacy review, mood (GDS), social support, and physical performance. CGA findings are then communicated back to the oncology team to inform treatment planning, dose modification, and supportive care decisions.

Evidence-Based Methodology

A cutoff <=14 is commonly used to select older adults who should receive comprehensive geriatric assessment.

Clinical Content Trust

Last reviewed:: April 21, 2026
Guideline version:: General evidence framework v2026.04
Source set version:: Primary-source set v1

How to Interpret Your Result

Lower G8 scores indicate higher vulnerability and support referral for comprehensive geriatric assessment.

When to Use This Tool

Use in older adults, especially oncology or complex chronic-care pathways, when rapid geriatric vulnerability triage is needed.

Limitations

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.

Sources

Bellera CA, et al. Screening older cancer patients: first evaluation of the G-8 geriatric screening tool.

Changelog

April 21, 2026 · trust-baseline
Clinical trust metadata enabled for this tool page with structured review/version fields.

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