Clinical calculator summary
Final 2018 combined-cohort CTS5
Clinical calculator summary
Final 2018 combined-cohort CTS5
A four-variable clinicopathologic score estimating distant recurrence risk during years 5-10 after 5 years of endocrine therapy.
Evidence-based context for fast calculator use
- Purpose:
- Support a late distant-recurrence risk discussion at the year-5 endocrine-therapy decision point.
- Population:
- Women postmenopausal at diagnosis with ER-positive early invasive breast cancer, distant-recurrence free after 5 years of endocrine therapy.
- Factors:
- Age at diagnosis, Pathologic invasive size, Histologic grade, Positive lymph nodes
- Reference:
- Dowsett et al. J Clin Oncol. 2018;36:1941-1948. PMID 29676944.
CTS5 Late Breast Cancer Recurrence
CTS5 is validated for postmenopausal patients with ER-positive early invasive breast cancer who completed 5 years of endocrine therapy and remain distant-recurrence free at year 5.
Clinical Context & Background
CTS5 = 0.438 x node group + 0.988 x (0.093 x capped size - 0.001 x capped size^2 + 0.375 x grade + 0.017 x age)Reference Data
| Raw CTS5 score | Years 5-10 distant recurrence band |
|---|---|
| < 3.13 | Low risk (<5%) |
| >= 3.13 and <= 3.86 | Intermediate risk (5-10%) |
| > 3.86 | High risk (>10%) |
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 at year 5 for a woman who was postmenopausal at diagnosis, had ER-positive early invasive breast cancer, completed 5 years of endocrine therapy, and remains distant-recurrence free.
- Enter age at diagnosis, pathologic invasive size in mm, grade 1-3, and the whole number of positive nodes.
How To Interpret
- Low, intermediate, and high groups correspond to source-defined years 5-10 distant recurrence bands of <5%, 5-10%, and >10%.
- The calculator classifies the unrounded score and displays the score to two decimals.
What To Do Next
- Use the result with toxicity, bone health, comorbidity, adherence, patient preference, tumor biology, and current guidelines.
- Document any size capping and preserve the distinction between recurrence prognosis and treatment-benefit prediction.
Limitations
- Not validated for premenopausal patients, DCIS, metastatic disease, recurrence in the first 5 years, or non-distant endpoints.
- CTS5 does not predict whether extended endocrine therapy will benefit an individual patient.
- Apply caution to HER2-positive disease because source-cohort treatment preceded routine trastuzumab.
Validated Population
Postmenopausal women in ATAC and BIG 1-98 with ER-positive early invasive disease who were distant-recurrence free after 5 years of endocrine therapy.
Publication example
Age 54, size 12 mm, grade 2, and 0 positive nodes gives CTS5 2.60832, displayed 2.61 (Low Risk).
Calculation verification history
Verified
Calculation verification history
Verified: Production browser revalidation
- Three source-backed node-count cases passed through visible controls on the newly published route at 0, 1, and 2 positive nodes.
- The zero-node control retained the entered value and calculated 2.61 / Low Late Recurrence Risk; the one- and two-node cases calculated 3.05 / Low and 3.48 / Intermediate.
- Reset and repeat-submission behavior passed; no stale control, unexpected N/A, literal undefined/null value, visible error boundary, or expected-versus-observed mismatch was observed.
Case-level production evidence is retained in validation/browser-revalidation/cts5-breast-cancer-late-recurrence-production-closure-2026-08-03.json.
: Zero-node control remediation verified locally
- Confirmed that the Positive lymph nodes number control preserves numeric zero through the controlled React value boundary and browser-number normalization.
- Three source-backed visible-control cases passed locally at 0, 1, and 2 positive nodes, including the published node-negative result of 2.61 / Low Late Recurrence Risk.
- Reset cleared age, size, grade, nodes, and the prior result; repeat submission passed and no browser console warning or error was emitted.
Local visible-control evidence is retained in validation/browser-revalidation/cts5-breast-cancer-late-recurrence-local-remediation-2026-08-03.json. Fresh production confirmation remains pending.
: Production browser revalidation found a control defect
- Two of three source-backed cases passed through visible production controls at one and two positive nodes.
- The published node-negative case failed because entering 0 positive nodes was cleared before submission and the form reported the field as required.
- This production finding remains open; exact reproduction evidence is retained.
Case-level evidence is retained in validation/browser-revalidation/cts5-breast-cancer-late-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 the route load.
- 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/cts5-breast-cancer-late-recurrence.json.
: Input workflow simplified and revalidated
- Reduced the public form to result-, branch-, unit-, and applicability-changing inputs; removed or consolidated non-scoring, administrative, and duplicate questions.
- Preserved the verified calculation or report-interpretation logic, thresholds, model version, component logic, and supported result pathways behind strict deterministic adapters.
- Passed the calculator-specific regression audit, adapter-parity and malformed-input checks, the 144-calculator input-quality audit, and the 43-calculator entry-burden audit.
: Full validation test
- 86/86 independent source, boundary, malformed-input, and applicability checks passed with zero numerical difference.
- Standalone only: repository search confirmed that no registered panel imports or calculates CTS5.
: Correction history
- Changed category assignment to use the unrounded raw score while retaining two-decimal display.
- Removed the preselected grade and unsupported age, size, and node maxima; values above 30 mm are accepted and visibly capped at 30 mm.
- Added strict exact-key validation, explicit source-population confirmation, neutral Not Applicable handling, and a full calculation trace.
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
Does CTS5 predict benefit from extended endocrine therapy?
No. CTS5 estimates years 5-10 distant recurrence risk; it does not predict treatment benefit.
What happens when tumor size is above 30 mm?
The entered size is accepted and shown, but the final 2018 equation caps the size used in both tumor-size terms at 30 mm.
Can CTS5 be used before menopause?
The original cohorts were postmenopausal at diagnosis, so this implementation returns Not Applicable when that population cannot be confirmed.
Evidence-based oncology decision support. Verify with clinical guidelines.