Clinical calculator summary
Original 1999 MSKCC Fong Clinical Risk Score
Clinical calculator summary
Original 1999 MSKCC Fong Clinical Risk Score
A five-factor additive preoperative score for colorectal liver metastases considered for hepatic resection.
Evidence-based context for fast calculator use
- Purpose:
- Reproduce the original cohort risk score and its score-specific historical 5-year actuarial survival row.
- Population:
- Adults with colorectal liver metastases evaluated before potentially curative hepatic resection.
- Factors:
- Primary tumor nodal status, Disease-free interval, Liver metastasis count, Largest metastasis size, Preoperative CEA
- Reference:
- Fong et al. Ann Surg. 1999;230(3):309-318. doi:10.1097/00000658-199909000-00004.
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Fong Clinical Risk Score (CRS)
months
cm
ng/mL
Clinical Context & Background
This calculator reproduces the original 1999 Memorial Sloan-Kettering Fong Clinical Risk Score for adults with colorectal liver metastases being evaluated before potentially curative hepatic resection. One point is assigned for each of five adverse factors: node-positive primary tumor, disease-free interval under 12 months, more than one liver metastasis, largest liver metastasis over 5 cm, and preoperative CEA over 200 ng/mL.
Disease-free interval means the time from treatment or resection of the colorectal primary to discovery of liver metastases; enter 0 months for synchronous disease. The historical outcomes reflect hepatic resections performed from 1985 to 1998 and may not represent contemporary systemic therapy. The score does not establish resectability, diagnose recurrence, or determine surveillance or treatment.
Formula Logic
Original 1999 Fong CRS = 1 point each for a node-positive primary, disease-free interval <12 months, >1 liver metastasis, largest liver metastasis >5 cm, and preoperative CEA >200 ng/mL.Reference Data
| Score | Original cohort 5-year actuarial survival | Evidence boundary |
|---|---|---|
| 0 | 60% | Historical cohort observation |
| 1 | 44% | Historical cohort observation |
| 2 | 40% | Historical cohort observation |
| 3 | 20% | Historical cohort observation |
| 4 | 25% | Historical cohort observation |
| 5 | 14% | Historical cohort observation |
Clinical Workflow
Use, Interpret, And Continue The Patient Pathway
Expand for workflow guidance, limitations, examples, and related next steps.
Clinical Workflow
Use, Interpret, And Continue The Patient Pathway
Expand for workflow guidance, limitations, examples, and related next steps.
When To Use
- Use preoperatively in adults with colorectal liver metastases being evaluated for potentially curative hepatic resection.
- Use raw unrounded values; enter synchronous liver metastases as a disease-free interval of 0 months.
How To Interpret
- Add one point for each source-defined adverse factor, for a total of 0-5.
- The displayed survival percentage is the exact score-specific 5-year actuarial observation from the original cohort, including the non-monotonic score-4 row.
What To Do Next
- Integrate the historical score with current multidisciplinary assessment, imaging, molecular findings, systemic-therapy context, technical resectability, and patient goals.
- Do not use this score alone to determine resectability, surveillance, transplantation, ablation, or systemic treatment.
Limitations
- Original MSKCC hepatic-resection cohort from 1985-1998; outcomes may not represent contemporary therapy.
- Not for non-colorectal liver metastases, primary colorectal cancer without liver metastases, postoperative recurrence diagnosis, or surveillance planning.
- Use after neoadjuvant therapy, ablation, transplantation, or other modern pathways is outside the original derivation context.
- Extrahepatic disease and positive margins were prognostic in the source but intentionally excluded from the five-factor preoperative score.
Validated Population
Original cohort: 1,001 consecutive hepatic resections for colorectal liver metastases at MSKCC from 1985 through 1998.
Equality example
Node-negative disease with DFI 12 months, one metastasis, largest size 5 cm, and CEA 200 ng/mL scores 0; each threshold requires a strict adverse inequality.
Calculation verification history
Verified
Calculation verification history
Verified: Production browser revalidation
- Five source-backed Fong CRS cases were exercised on the public production route through visible controls; 5/5 expected scores and historical survival values matched across scores 0, 1, 2, 4, and 5.
- No unexpected N/A, literal undefined value, stale control, or browser-console error was observed.
Case-level evidence is retained in validation/browser-revalidation/fong-recurrence-2026-08-03.json.
: Production browser validation
- Ten source-backed cases were exercised on the public production route through visible browser controls; 10/10 case records passed their expected-versus-observed assertions across 11 visible submissions.
- Overall browser status: failed-console. medium: Production emitted minified React error #418 during route loads/reloads used by this run.
- Case-level inputs, expected and observed results, reset/repeat behavior, failure reproductions, and console evidence are retained in the production-browser evidence record.
Case-level production evidence is retained in validation/browser-production/fong-recurrence.json.
: Browser input adapter corrected and reverified
- Accepted finite number values already normalized by the shared calculator form while retaining strict malformed-input rejection.
- No equation, cutoff, unit, classification, or applicability rule changed; calculator-specific verification and the calculator-wide browser-input audit passed.
: Full validation test
- 370/370 independent source-rule, exact-boundary, malformed-input, UI, outcome, trace, reset, and immutability checks passed.
- The colorectal panel does not calculate Fong CRS, remains unchanged, and receives no inherited Fong verification.
: Calculation and input-contract correction
- Replaced five pre-scored favorable binary defaults with required raw nodal status, disease-free interval, metastasis count, largest size, and preoperative CEA inputs; missing, extra, coercive, nonfinite, fractional-count, and out-of-domain values are rejected.
- Enforced the original strict adverse thresholds and restored all six source-specific 5-year actuarial survival rows without invented recurrence-risk grouping, surveillance claims, individualized prognosis, resectability, or treatment claims.
Verification confirms the calculator implementation against the cited model; it is not independent clinical validation, regulatory approval, or medical advice.
Related Tools
Frequently Asked Questions
What is the disease-free interval?
It is the time from treatment or resection of the colorectal primary to discovery of liver metastases. Enter 0 months for synchronous disease.
Do values exactly at 12 months, 5 cm, or 200 ng/mL score a point?
No. The adverse criteria are DFI under 12 months, largest metastasis over 5 cm, and CEA over 200 ng/mL.
Does the Fong score determine whether liver metastases are resectable?
No. It is a historical prognostic score and does not establish technical or oncologic resectability or prescribe treatment.
Evidence-based oncology decision support. Verify with clinical guidelines.